* [PATCHv15 0/8] Contiguous Memory Allocator @ 2011-08-19 14:27 Marek Szyprowski 2011-08-19 14:27 ` [PATCH 1/8] mm: move some functions from memory_hotplug.c to page_isolation.c Marek Szyprowski ` (7 more replies) 0 siblings, 8 replies; 46+ messages in thread From: Marek Szyprowski @ 2011-08-19 14:27 UTC (permalink / raw) To: linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig Cc: Michal Nazarewicz, Marek Szyprowski, Kyungmin Park, Russell King, Andrew Morton, KAMEZAWA Hiroyuki, Ankita Garg, Daniel Walker, Mel Gorman, Arnd Bergmann, Jesse Barker, Jonathan Corbet, Shariq Hasnain, Chunsang Jeong Hello again, This is yet another round of Contiguous Memory Allocator patches. Now I implemented all the ideas that has been discussed during Linaro Sprint meeting. This version provides a solution for complete integration of CMA to DMA mapping subsystem on ARM architecture. The issue caused by double dma pages mapping and possible aliasing in coherent memory mapping has been finally resolved, both for GFP_ATOMIC case (allocations comes from coherent memory pool) and non-GFP_ATOMIC case (allocations comes from CMA managed areas). For coherent, nommu, ARMv4 and ARMv5 systems the current DMA-mapping implementation has been kept. For ARMv6+ systems, CMA has been enabled and a special pool of coherent memory for atomic allocations has been created. The size of this pool defaults to CONSISTEN_DMA_SIZE/8, but can be changed with coherent_pool kernel parameter (if really required). All atomic allocations are served from this pool. I've did a little simplification here, because there is no separate pool for writecombine memory - such requests are also served from coherent pool. I don't think that such simplification is a problem here - I found no driver that use dma_alloc_writecombine with GFP_ATOMIC flags. All non-atomic allocation are served from CMA area. Kernel mapping is updated to reflect required memory attributes changes. This is possible because during early boot, all CMA area are remapped with 4KiB pages in kernel low-memory. This version have been tested on Samsung S5PC110 based Goni machine and Exynos4 UniversalC210 board with various V4L2 multimedia drivers. Coherent atomic allocations has been tested by manually enabling the dma bounce for the s3c-sdhci device. All patches are prepared for Linux Kernel v3.1-rc2. A few words for these who see CMA for the first time: The Contiguous Memory Allocator (CMA) makes it possible for device drivers to allocate big contiguous chunks of memory after the system has booted. The main difference from the similar frameworks is the fact that CMA allows to transparently reuse memory region reserved for the big chunk allocation as a system memory, so no memory is wasted when no big chunk is allocated. Once the alloc request is issued, the framework will migrate system pages to create a required big chunk of physically contiguous memory. For more information you can refer to nice LWN articles: http://lwn.net/Articles/447405/ and http://lwn.net/Articles/450286/ as well as links to previous versions of the CMA framework. The CMA framework has been initially developed by Michal Nazarewicz at Samsung Poland R&D Center. Since version 9, I've taken over the development, because Michal has left the company. TODO (optional): - implement support for contiguous memory areas placed in HIGHMEM zone Best regards -- Marek Szyprowski Samsung Poland R&D Center Links to previous versions of the patchset: v14: <http://www.spinics.net/lists/linux-media/msg36536.html> v13: (internal, intentionally not released) v12: <http://www.spinics.net/lists/linux-media/msg35674.html> v11: <http://www.spinics.net/lists/linux-mm/msg21868.html> v10: <http://www.spinics.net/lists/linux-mm/msg20761.html> v9: <http://article.gmane.org/gmane.linux.kernel.mm/60787> v8: <http://article.gmane.org/gmane.linux.kernel.mm/56855> v7: <http://article.gmane.org/gmane.linux.kernel.mm/55626> v6: <http://article.gmane.org/gmane.linux.kernel.mm/55626> v5: (intentionally left out as CMA v5 was identical to CMA v4) v4: <http://article.gmane.org/gmane.linux.kernel.mm/52010> v3: <http://article.gmane.org/gmane.linux.kernel.mm/51573> v2: <http://article.gmane.org/gmane.linux.kernel.mm/50986> v1: <http://article.gmane.org/gmane.linux.kernel.mm/50669> Changelog: v15: 1. fixed calculation of the total memory after activating CMA area (was broken from v12) 2. more code cleanup in drivers/base/dma-contiguous.c 3. added address limit for default CMA area 4. rewrote ARM DMA integration: - removed "ARM: DMA: steal memory for DMA coherent mappings" patch - kept current DMA mapping implementation for coherent, nommu and ARMv4/ARMv5 systems - enabled CMA for all ARMv6+ systems - added separate, small pool for coherent atomic allocations, defaults to CONSISTENT_DMA_SIZE/8, but can be changed with kernel parameter coherent_pool=[size] v14: 1. Merged with "ARM: DMA: steal memory for DMA coherent mappings" patch, added support for GFP_ATOMIC allocations. 2. Added checks for NULL device pointer v13: (internal, intentionally not released) v12: 1. Fixed 2 nasty bugs in dma-contiguous allocator: - alignment argument was not passed correctly - range for dma_release_from_contiguous was not checked correctly 2. Added support for architecture specfic dma_contiguous_early_fixup() function 3. CMA and DMA-mapping integration for ARM architechture has been rewritten to take care of the memory aliasing issue that might happen for newer ARM CPUs (mapping of the same pages with different cache attributes is forbidden). TODO: add support for GFP_ATOMIC allocations basing on the "ARM: DMA: steal memory for DMA coherent mappings" patch and implement support for contiguous memory areas that are placed in HIGHMEM zone v11: 1. Removed genalloc usage and replaced it with direct calls to bitmap_* functions, dropped patches that are not needed anymore (genalloc extensions) 2. Moved all contiguous area management code from mm/cma.c to drivers/base/dma-contiguous.c 3. Renamed cm_alloc/free to dma_alloc/release_from_contiguous 4. Introduced global, system wide (default) contiguous area configured with kernel config and kernel cmdline parameters 5. Simplified initialization to just one function: dma_declare_contiguous() 6. Added example of device private memory contiguous area v10: 1. Rebased onto 3.0-rc2 and resolved all conflicts 2. Simplified CMA to be just a pure memory allocator, for use with platfrom/bus specific subsystems, like dma-mapping. Removed all device specific functions are calls. 3. Integrated with ARM DMA-mapping subsystem. 4. Code cleanup here and there. 5. Removed private context support. v9: 1. Rebased onto 2.6.39-rc1 and resolved all conflicts 2. Fixed a bunch of nasty bugs that happened when the allocation failed (mainly kernel oops due to NULL ptr dereference). 3. Introduced testing code: cma-regions compatibility layer and videobuf2-cma memory allocator module. v8: 1. The alloc_contig_range() function has now been separated from CMA and put in page_allocator.c. This function tries to migrate all LRU pages in specified range and then allocate the range using alloc_contig_freed_pages(). 2. Support for MIGRATE_CMA has been separated from the CMA code. I have not tested if CMA works with ZONE_MOVABLE but I see no reasons why it shouldn't. 3. I have added a @private argument when creating CMA contexts so that one can reserve memory and not share it with the rest of the system. This way, CMA acts only as allocation algorithm. v7: 1. A lot of functionality that handled driver->allocator_context mapping has been removed from the patchset. This is not to say that this code is not needed, it's just not worth posting everything in one patchset. Currently, CMA is "just" an allocator. It uses it's own migratetype (MIGRATE_CMA) for defining ranges of pageblokcs which behave just like ZONE_MOVABLE but dispite the latter can be put in arbitrary places. 2. The migration code that was introduced in the previous version actually started working. v6: 1. Most importantly, v6 introduces support for memory migration. The implementation is not yet complete though. Migration support means that when CMA is not using memory reserved for it, page allocator can allocate pages from it. When CMA wants to use the memory, the pages have to be moved and/or evicted as to make room for CMA. To make it possible it must be guaranteed that only movable and reclaimable pages are allocated in CMA controlled regions. This is done by introducing a MIGRATE_CMA migrate type that guarantees exactly that. Some of the migration code is "borrowed" from Kamezawa Hiroyuki's alloc_contig_pages() implementation. The main difference is that thanks to MIGRATE_CMA migrate type CMA assumes that memory controlled by CMA are is always movable or reclaimable so that it makes allocation decisions regardless of the whether some pages are actually allocated and migrates them if needed. The most interesting patches from the patchset that implement the functionality are: 09/13: mm: alloc_contig_free_pages() added 10/13: mm: MIGRATE_CMA migration type added 11/13: mm: MIGRATE_CMA isolation functions added 12/13: mm: cma: Migration support added [wip] Currently, kernel panics in some situations which I am trying to investigate. 2. cma_pin() and cma_unpin() functions has been added (after a conversation with Johan Mossberg). The idea is that whenever hardware does not use the memory (no transaction is on) the chunk can be moved around. This would allow defragmentation to be implemented if desired. No defragmentation algorithm is provided at this time. 3. Sysfs support has been replaced with debugfs. I always felt unsure about the sysfs interface and when Greg KH pointed it out I finally got to rewrite it to debugfs. v5: (intentionally left out as CMA v5 was identical to CMA v4) v4: 1. The "asterisk" flag has been removed in favour of requiring that platform will provide a "*=<regions>" rule in the map attribute. 2. The terminology has been changed slightly renaming "kind" to "type" of memory. In the previous revisions, the documentation indicated that device drivers define memory kinds and now, v3: 1. The command line parameters have been removed (and moved to a separate patch, the fourth one). As a consequence, the cma_set_defaults() function has been changed -- it no longer accepts a string with list of regions but an array of regions. 2. The "asterisk" attribute has been removed. Now, each region has an "asterisk" flag which lets one specify whether this region should by considered "asterisk" region. 3. SysFS support has been moved to a separate patch (the third one in the series) and now also includes list of regions. v2: 1. The "cma_map" command line have been removed. In exchange, a SysFS entry has been created under kernel/mm/contiguous. The intended way of specifying the attributes is a cma_set_defaults() function called by platform initialisation code. "regions" attribute (the string specified by "cma" command line parameter) can be overwritten with command line parameter; the other attributes can be changed during run-time using the SysFS entries. 2. The behaviour of the "map" attribute has been modified slightly. Currently, if no rule matches given device it is assigned regions specified by the "asterisk" attribute. It is by default built from the region names given in "regions" attribute. 3. Devices can register private regions as well as regions that can be shared but are not reserved using standard CMA mechanisms. A private region has no name and can be accessed only by devices that have the pointer to it. 4. The way allocators are registered has changed. Currently, a cma_allocator_register() function is used for that purpose. Moreover, allocators are attached to regions the first time memory is registered from the region or when allocator is registered which means that allocators can be dynamic modules that are loaded after the kernel booted (of course, it won't be possible to allocate a chunk of memory from a region if allocator is not loaded). 5. Index of new functions: +static inline dma_addr_t __must_check +cma_alloc_from(const char *regions, size_t size, + dma_addr_t alignment) +static inline int +cma_info_about(struct cma_info *info, const const char *regions) +int __must_check cma_region_register(struct cma_region *reg); +dma_addr_t __must_check +cma_alloc_from_region(struct cma_region *reg, + size_t size, dma_addr_t alignment); +static inline dma_addr_t __must_check +cma_alloc_from(const char *regions, + size_t size, dma_addr_t alignment); +int cma_allocator_register(struct cma_allocator *alloc); Patches in this patchset: mm: move some functions from memory_hotplug.c to page_isolation.c mm: alloc_contig_freed_pages() added Code "stolen" from Kamezawa. The first patch just moves code around and the second provide function for "allocates" already freed memory. mm: alloc_contig_range() added This is what Kamezawa asked: a function that tries to migrate all pages from given range and then use alloc_contig_freed_pages() (defined by the previous commit) to allocate those pages. mm: MIGRATE_CMA migration type added mm: MIGRATE_CMA isolation functions added Introduction of the new migratetype and support for it in CMA. MIGRATE_CMA works similar to ZONE_MOVABLE expect almost any memory range can be marked as one. mm: cma: Contiguous Memory Allocator added The code CMA code. Manages CMA contexts and performs memory allocations. ARM: integrate CMA with dma-mapping subsystem Main client of CMA frame work. CMA serves as a alloc_pages() replacement. ARM: S5PV210: example of CMA private area for FIMC device on Goni board Example of platform/board specific code that creates cma context and assigns it to particular device. Patch summary: KAMEZAWA Hiroyuki (2): mm: move some functions from memory_hotplug.c to page_isolation.c mm: alloc_contig_freed_pages() added Marek Szyprowski (3): drivers: add Contiguous Memory Allocator ARM: integrate CMA with DMA-mapping subsystem ARM: S5PV210: example of CMA private area for FIMC device on Goni board Michal Nazarewicz (3): mm: alloc_contig_range() added mm: MIGRATE_CMA migration type added mm: MIGRATE_CMA isolation functions added arch/Kconfig | 3 + arch/arm/Kconfig | 2 + arch/arm/include/asm/device.h | 3 + arch/arm/include/asm/dma-contiguous.h | 33 +++ arch/arm/include/asm/mach/map.h | 1 + arch/arm/mach-s5pv210/mach-goni.c | 4 + arch/arm/mm/dma-mapping.c | 362 +++++++++++++++++++++++++------ arch/arm/mm/init.c | 8 + arch/arm/mm/mm.h | 3 + arch/arm/mm/mmu.c | 29 ++- drivers/base/Kconfig | 79 +++++++ drivers/base/Makefile | 1 + drivers/base/dma-contiguous.c | 386 +++++++++++++++++++++++++++++++++ include/linux/dma-contiguous.h | 102 +++++++++ include/linux/mmzone.h | 41 +++- include/linux/page-isolation.h | 51 ++++- mm/Kconfig | 8 +- mm/compaction.c | 10 + mm/memory_hotplug.c | 111 ---------- mm/page_alloc.c | 287 ++++++++++++++++++++++-- mm/page_isolation.c | 129 +++++++++++- 21 files changed, 1417 insertions(+), 236 deletions(-) create mode 100644 arch/arm/include/asm/dma-contiguous.h create mode 100644 drivers/base/dma-contiguous.c create mode 100644 include/linux/dma-contiguous.h -- 1.7.1.569.g6f426 ^ permalink raw reply [flat|nested] 46+ messages in thread
* [PATCH 1/8] mm: move some functions from memory_hotplug.c to page_isolation.c 2011-08-19 14:27 [PATCHv15 0/8] Contiguous Memory Allocator Marek Szyprowski @ 2011-08-19 14:27 ` Marek Szyprowski 2011-08-19 14:27 ` [PATCH 2/8] mm: alloc_contig_freed_pages() added Marek Szyprowski ` (6 subsequent siblings) 7 siblings, 0 replies; 46+ messages in thread From: Marek Szyprowski @ 2011-08-19 14:27 UTC (permalink / raw) To: linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig Cc: Michal Nazarewicz, Marek Szyprowski, Kyungmin Park, Russell King, Andrew Morton, KAMEZAWA Hiroyuki, Ankita Garg, Daniel Walker, Mel Gorman, Arnd Bergmann, Jesse Barker, Jonathan Corbet, Shariq Hasnain, Chunsang Jeong From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Memory hotplug is a logic for making pages unused in the specified range of pfn. So, some of core logics can be used for other purpose as allocating a very large contigous memory block. This patch moves some functions from mm/memory_hotplug.c to mm/page_isolation.c. This helps adding a function for large-alloc in page_isolation.c with memory-unplug technique. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> [m.nazarewicz: reworded commit message] Signed-off-by: Michal Nazarewicz <m.nazarewicz@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> [m.szyprowski: rebased and updated to Linux v3.0-rc1] Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> CC: Michal Nazarewicz <mina86@mina86.com> Acked-by: Arnd Bergmann <arnd@arndb.de> --- include/linux/page-isolation.h | 7 +++ mm/memory_hotplug.c | 111 -------------------------------------- mm/page_isolation.c | 114 ++++++++++++++++++++++++++++++++++++++++ 3 files changed, 121 insertions(+), 111 deletions(-) diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h index 051c1b1..58cdbac 100644 --- a/include/linux/page-isolation.h +++ b/include/linux/page-isolation.h @@ -33,5 +33,12 @@ test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn); extern int set_migratetype_isolate(struct page *page); extern void unset_migratetype_isolate(struct page *page); +/* + * For migration. + */ + +int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn); +unsigned long scan_lru_pages(unsigned long start, unsigned long end); +int do_migrate_range(unsigned long start_pfn, unsigned long end_pfn); #endif diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 6e7d8b2..3419dd6 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -707,117 +707,6 @@ int is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages) } /* - * Confirm all pages in a range [start, end) is belongs to the same zone. - */ -static int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn) -{ - unsigned long pfn; - struct zone *zone = NULL; - struct page *page; - int i; - for (pfn = start_pfn; - pfn < end_pfn; - pfn += MAX_ORDER_NR_PAGES) { - i = 0; - /* This is just a CONFIG_HOLES_IN_ZONE check.*/ - while ((i < MAX_ORDER_NR_PAGES) && !pfn_valid_within(pfn + i)) - i++; - if (i == MAX_ORDER_NR_PAGES) - continue; - page = pfn_to_page(pfn + i); - if (zone && page_zone(page) != zone) - return 0; - zone = page_zone(page); - } - return 1; -} - -/* - * Scanning pfn is much easier than scanning lru list. - * Scan pfn from start to end and Find LRU page. - */ -static unsigned long scan_lru_pages(unsigned long start, unsigned long end) -{ - unsigned long pfn; - struct page *page; - for (pfn = start; pfn < end; pfn++) { - if (pfn_valid(pfn)) { - page = pfn_to_page(pfn); - if (PageLRU(page)) - return pfn; - } - } - return 0; -} - -static struct page * -hotremove_migrate_alloc(struct page *page, unsigned long private, int **x) -{ - /* This should be improooooved!! */ - return alloc_page(GFP_HIGHUSER_MOVABLE); -} - -#define NR_OFFLINE_AT_ONCE_PAGES (256) -static int -do_migrate_range(unsigned long start_pfn, unsigned long end_pfn) -{ - unsigned long pfn; - struct page *page; - int move_pages = NR_OFFLINE_AT_ONCE_PAGES; - int not_managed = 0; - int ret = 0; - LIST_HEAD(source); - - for (pfn = start_pfn; pfn < end_pfn && move_pages > 0; pfn++) { - if (!pfn_valid(pfn)) - continue; - page = pfn_to_page(pfn); - if (!get_page_unless_zero(page)) - continue; - /* - * We can skip free pages. And we can only deal with pages on - * LRU. - */ - ret = isolate_lru_page(page); - if (!ret) { /* Success */ - put_page(page); - list_add_tail(&page->lru, &source); - move_pages--; - inc_zone_page_state(page, NR_ISOLATED_ANON + - page_is_file_cache(page)); - - } else { -#ifdef CONFIG_DEBUG_VM - printk(KERN_ALERT "removing pfn %lx from LRU failed\n", - pfn); - dump_page(page); -#endif - put_page(page); - /* Because we don't have big zone->lock. we should - check this again here. */ - if (page_count(page)) { - not_managed++; - ret = -EBUSY; - break; - } - } - } - if (!list_empty(&source)) { - if (not_managed) { - putback_lru_pages(&source); - goto out; - } - /* this function returns # of failed pages */ - ret = migrate_pages(&source, hotremove_migrate_alloc, 0, - true, true); - if (ret) - putback_lru_pages(&source); - } -out: - return ret; -} - -/* * remove from free_area[] and mark all as Reserved. */ static int diff --git a/mm/page_isolation.c b/mm/page_isolation.c index 4ae42bb..270a026 100644 --- a/mm/page_isolation.c +++ b/mm/page_isolation.c @@ -5,6 +5,9 @@ #include <linux/mm.h> #include <linux/page-isolation.h> #include <linux/pageblock-flags.h> +#include <linux/memcontrol.h> +#include <linux/migrate.h> +#include <linux/mm_inline.h> #include "internal.h" static inline struct page * @@ -139,3 +142,114 @@ int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn) spin_unlock_irqrestore(&zone->lock, flags); return ret ? 0 : -EBUSY; } + + +/* + * Confirm all pages in a range [start, end) is belongs to the same zone. + */ +int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn) +{ + unsigned long pfn; + struct zone *zone = NULL; + struct page *page; + int i; + for (pfn = start_pfn; + pfn < end_pfn; + pfn += MAX_ORDER_NR_PAGES) { + i = 0; + /* This is just a CONFIG_HOLES_IN_ZONE check.*/ + while ((i < MAX_ORDER_NR_PAGES) && !pfn_valid_within(pfn + i)) + i++; + if (i == MAX_ORDER_NR_PAGES) + continue; + page = pfn_to_page(pfn + i); + if (zone && page_zone(page) != zone) + return 0; + zone = page_zone(page); + } + return 1; +} + +/* + * Scanning pfn is much easier than scanning lru list. + * Scan pfn from start to end and Find LRU page. + */ +unsigned long scan_lru_pages(unsigned long start, unsigned long end) +{ + unsigned long pfn; + struct page *page; + for (pfn = start; pfn < end; pfn++) { + if (pfn_valid(pfn)) { + page = pfn_to_page(pfn); + if (PageLRU(page)) + return pfn; + } + } + return 0; +} + +struct page * +hotremove_migrate_alloc(struct page *page, unsigned long private, int **x) +{ + /* This should be improooooved!! */ + return alloc_page(GFP_HIGHUSER_MOVABLE); +} + +#define NR_OFFLINE_AT_ONCE_PAGES (256) +int do_migrate_range(unsigned long start_pfn, unsigned long end_pfn) +{ + unsigned long pfn; + struct page *page; + int move_pages = NR_OFFLINE_AT_ONCE_PAGES; + int not_managed = 0; + int ret = 0; + LIST_HEAD(source); + + for (pfn = start_pfn; pfn < end_pfn && move_pages > 0; pfn++) { + if (!pfn_valid(pfn)) + continue; + page = pfn_to_page(pfn); + if (!get_page_unless_zero(page)) + continue; + /* + * We can skip free pages. And we can only deal with pages on + * LRU. + */ + ret = isolate_lru_page(page); + if (!ret) { /* Success */ + put_page(page); + list_add_tail(&page->lru, &source); + move_pages--; + inc_zone_page_state(page, NR_ISOLATED_ANON + + page_is_file_cache(page)); + + } else { +#ifdef CONFIG_DEBUG_VM + printk(KERN_ALERT "removing pfn %lx from LRU failed\n", + pfn); + dump_page(page); +#endif + put_page(page); + /* Because we don't have big zone->lock. we should + check this again here. */ + if (page_count(page)) { + not_managed++; + ret = -EBUSY; + break; + } + } + } + if (!list_empty(&source)) { + if (not_managed) { + putback_lru_pages(&source); + goto out; + } + /* this function returns # of failed pages */ + ret = migrate_pages(&source, hotremove_migrate_alloc, 0, + true, true); + if (ret) + putback_lru_pages(&source); + } +out: + return ret; +} -- 1.7.1.569.g6f426 ^ permalink raw reply related [flat|nested] 46+ messages in thread
* [PATCH 2/8] mm: alloc_contig_freed_pages() added 2011-08-19 14:27 [PATCHv15 0/8] Contiguous Memory Allocator Marek Szyprowski 2011-08-19 14:27 ` [PATCH 1/8] mm: move some functions from memory_hotplug.c to page_isolation.c Marek Szyprowski @ 2011-08-19 14:27 ` Marek Szyprowski 2011-09-08 18:05 ` Dave Hansen 2011-08-19 14:27 ` [PATCH 3/8] mm: alloc_contig_range() added Marek Szyprowski ` (5 subsequent siblings) 7 siblings, 1 reply; 46+ messages in thread From: Marek Szyprowski @ 2011-08-19 14:27 UTC (permalink / raw) To: linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig Cc: Michal Nazarewicz, Marek Szyprowski, Kyungmin Park, Russell King, Andrew Morton, KAMEZAWA Hiroyuki, Ankita Garg, Daniel Walker, Mel Gorman, Arnd Bergmann, Jesse Barker, Jonathan Corbet, Shariq Hasnain, Chunsang Jeong From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> This commit introduces alloc_contig_freed_pages() function which allocates (ie. removes from buddy system) free pages in range. Caller has to guarantee that all pages in range are in buddy system. Along with this function, a free_contig_pages() function is provided which frees all (or a subset of) pages allocated with alloc_contig_free_pages(). Michal Nazarewicz has modified the function to make it easier to allocate not MAX_ORDER_NR_PAGES aligned pages by making it return pfn of one-past-the-last allocated page. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Michal Nazarewicz <m.nazarewicz@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> CC: Michal Nazarewicz <mina86@mina86.com> Acked-by: Arnd Bergmann <arnd@arndb.de> --- include/linux/page-isolation.h | 3 ++ mm/page_alloc.c | 44 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 47 insertions(+), 0 deletions(-) diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h index 58cdbac..f1417ed 100644 --- a/include/linux/page-isolation.h +++ b/include/linux/page-isolation.h @@ -32,6 +32,9 @@ test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn); */ extern int set_migratetype_isolate(struct page *page); extern void unset_migratetype_isolate(struct page *page); +extern unsigned long alloc_contig_freed_pages(unsigned long start, + unsigned long end, gfp_t flag); +extern void free_contig_pages(struct page *page, int nr_pages); /* * For migration. diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 6e8ecb6..ad6ae3f 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5668,6 +5668,50 @@ out: spin_unlock_irqrestore(&zone->lock, flags); } +unsigned long alloc_contig_freed_pages(unsigned long start, unsigned long end, + gfp_t flag) +{ + unsigned long pfn = start, count; + struct page *page; + struct zone *zone; + int order; + + VM_BUG_ON(!pfn_valid(start)); + zone = page_zone(pfn_to_page(start)); + + spin_lock_irq(&zone->lock); + + page = pfn_to_page(pfn); + for (;;) { + VM_BUG_ON(page_count(page) || !PageBuddy(page)); + list_del(&page->lru); + order = page_order(page); + zone->free_area[order].nr_free--; + rmv_page_order(page); + __mod_zone_page_state(zone, NR_FREE_PAGES, -(1UL << order)); + pfn += 1 << order; + if (pfn >= end) + break; + VM_BUG_ON(!pfn_valid(pfn)); + page += 1 << order; + } + + spin_unlock_irq(&zone->lock); + + /* After this, pages in the range can be freed one be one */ + page = pfn_to_page(start); + for (count = pfn - start; count; --count, ++page) + prep_new_page(page, 0, flag); + + return pfn; +} + +void free_contig_pages(struct page *page, int nr_pages) +{ + for (; nr_pages; --nr_pages, ++page) + __free_page(page); +} + #ifdef CONFIG_MEMORY_HOTREMOVE /* * All pages in the range must be isolated before calling this. -- 1.7.1.569.g6f426 ^ permalink raw reply related [flat|nested] 46+ messages in thread
* Re: [PATCH 2/8] mm: alloc_contig_freed_pages() added 2011-08-19 14:27 ` [PATCH 2/8] mm: alloc_contig_freed_pages() added Marek Szyprowski @ 2011-09-08 18:05 ` Dave Hansen 2011-09-21 13:17 ` Michal Nazarewicz 2011-09-21 15:19 ` [PATCH 1/3] fixup! " Michal Nazarewicz 0 siblings, 2 replies; 46+ messages in thread From: Dave Hansen @ 2011-09-08 18:05 UTC (permalink / raw) To: Marek Szyprowski Cc: linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig, Michal Nazarewicz, Kyungmin Park, Russell King, Andrew Morton, KAMEZAWA Hiroyuki, Ankita Garg, Daniel Walker, Mel Gorman, Arnd Bergmann, Jesse Barker, Jonathan Corbet, Shariq Hasnain, Chunsang Jeong On Fri, 2011-08-19 at 16:27 +0200, Marek Szyprowski wrote: > +unsigned long alloc_contig_freed_pages(unsigned long start, unsigned long end, > + gfp_t flag) > +{ > + unsigned long pfn = start, count; > + struct page *page; > + struct zone *zone; > + int order; > + > + VM_BUG_ON(!pfn_valid(start)); > + zone = page_zone(pfn_to_page(start)); This implies that start->end are entirely contained in a single zone. What enforces that? If some higher layer enforces that, I think we probably need at least a VM_BUG_ON() in here and a comment about who enforces it. > + spin_lock_irq(&zone->lock); > + > + page = pfn_to_page(pfn); > + for (;;) { > + VM_BUG_ON(page_count(page) || !PageBuddy(page)); > + list_del(&page->lru); > + order = page_order(page); > + zone->free_area[order].nr_free--; > + rmv_page_order(page); > + __mod_zone_page_state(zone, NR_FREE_PAGES, -(1UL << order)); > + pfn += 1 << order; > + if (pfn >= end) > + break; > + VM_BUG_ON(!pfn_valid(pfn)); > + page += 1 << order; > + } This 'struct page *'++ stuff is OK, but only for small, aligned areas. For at least some of the sparsemem modes (non-VMEMMAP), you could walk off of the end of the section_mem_map[] when you cross a MAX_ORDER boundary. I'd feel a little bit more comfortable if pfn_to_page() was being done each time, or only occasionally when you cross a section boundary. This may not apply to what ARM is doing today, but it shouldn't be too difficult to fix up, or to document what's going on. > + spin_unlock_irq(&zone->lock); > + > + /* After this, pages in the range can be freed one be one */ > + page = pfn_to_page(start); > + for (count = pfn - start; count; --count, ++page) > + prep_new_page(page, 0, flag); > + > + return pfn; > +} > + > +void free_contig_pages(struct page *page, int nr_pages) > +{ > + for (; nr_pages; --nr_pages, ++page) > + __free_page(page); > +} The same thing about 'struct page' pointer math goes here. -- Dave ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 2/8] mm: alloc_contig_freed_pages() added 2011-09-08 18:05 ` Dave Hansen @ 2011-09-21 13:17 ` Michal Nazarewicz 2011-09-21 14:07 ` Dave Hansen 2011-09-21 15:19 ` [PATCH 1/3] fixup! " Michal Nazarewicz 1 sibling, 1 reply; 46+ messages in thread From: Michal Nazarewicz @ 2011-09-21 13:17 UTC (permalink / raw) To: Marek Szyprowski, Dave Hansen Cc: linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig, Kyungmin Park, Russell King, Andrew Morton, KAMEZAWA Hiroyuki, Ankita Garg, Daniel Walker, Mel Gorman, Arnd Bergmann, Jesse Barker, Jonathan Corbet, Shariq Hasnain, Chunsang Jeong On Thu, 08 Sep 2011 20:05:52 +0200, Dave Hansen <dave@linux.vnet.ibm.com> wrote: > On Fri, 2011-08-19 at 16:27 +0200, Marek Szyprowski wrote: >> +unsigned long alloc_contig_freed_pages(unsigned long start, unsigned >> long end, >> + gfp_t flag) >> +{ >> + unsigned long pfn = start, count; >> + struct page *page; >> + struct zone *zone; >> + int order; >> + >> + VM_BUG_ON(!pfn_valid(start)); >> + zone = page_zone(pfn_to_page(start)); > > This implies that start->end are entirely contained in a single zone. > What enforces that? In case of CMA, the __cma_activate_area() function from 6/8 has the check: 151 VM_BUG_ON(!pfn_valid(pfn)); 152 VM_BUG_ON(page_zone(pfn_to_page(pfn)) != zone); This guarantees that CMA will never try to call alloc_contig_freed_pages() on a region that spans multiple regions. > If some higher layer enforces that, I think we probably need at least > a VM_BUG_ON() in here and a comment about who enforces it. Agreed. >> + spin_lock_irq(&zone->lock); >> + >> + page = pfn_to_page(pfn); >> + for (;;) { >> + VM_BUG_ON(page_count(page) || !PageBuddy(page)); >> + list_del(&page->lru); >> + order = page_order(page); >> + zone->free_area[order].nr_free--; >> + rmv_page_order(page); >> + __mod_zone_page_state(zone, NR_FREE_PAGES, -(1UL << order)); >> + pfn += 1 << order; >> + if (pfn >= end) >> + break; >> + VM_BUG_ON(!pfn_valid(pfn)); >> + page += 1 << order; >> + } > This 'struct page *'++ stuff is OK, but only for small, aligned areas. > For at least some of the sparsemem modes (non-VMEMMAP), you could walk > off of the end of the section_mem_map[] when you cross a MAX_ORDER > boundary. I'd feel a little bit more comfortable if pfn_to_page() was > being done each time, or only occasionally when you cross a section > boundary. I'm fine with that. I've used pointer arithmetic for performance reasons but if that may potentially lead to bugs then obviously pfn_to_page() should be used. -- Best regards, _ _ .o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o ..o | Computer Science, Michal "mina86" Nazarewicz (o o) ooo +-----<email/xmpp: mnazarewicz@google.com>-----ooO--(_)--Ooo-- ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 2/8] mm: alloc_contig_freed_pages() added 2011-09-21 13:17 ` Michal Nazarewicz @ 2011-09-21 14:07 ` Dave Hansen 0 siblings, 0 replies; 46+ messages in thread From: Dave Hansen @ 2011-09-21 14:07 UTC (permalink / raw) To: Michal Nazarewicz Cc: Marek Szyprowski, linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig, Kyungmin Park, Russell King, Andrew Morton, KAMEZAWA Hiroyuki, Ankita Garg, Daniel Walker, Mel Gorman, Arnd Bergmann, Jesse Barker, Jonathan Corbet, Shariq Hasnain, Chunsang Jeong On Wed, 2011-09-21 at 15:17 +0200, Michal Nazarewicz wrote: > > This 'struct page *'++ stuff is OK, but only for small, aligned areas. > > For at least some of the sparsemem modes (non-VMEMMAP), you could walk > > off of the end of the section_mem_map[] when you cross a MAX_ORDER > > boundary. I'd feel a little bit more comfortable if pfn_to_page() was > > being done each time, or only occasionally when you cross a section > > boundary. > > I'm fine with that. I've used pointer arithmetic for performance reasons > but if that may potentially lead to bugs then obviously pfn_to_page() > should be used pfn_to_page() on x86 these days is usually: #define __pfn_to_page(pfn) (vmemmap + (pfn)) Even for the non-vmemmap sparsemem it stays pretty quick because the section array is in cache as you run through the loop. There are ways to _minimize_ the number of pfn_to_page() calls by checking when you cross a section boundary, or even at a MAX_ORDER_NR_PAGES boundary. But, I don't think it's worth the trouble. -- Dave ^ permalink raw reply [flat|nested] 46+ messages in thread
* [PATCH 1/3] fixup! mm: alloc_contig_freed_pages() added 2011-09-08 18:05 ` Dave Hansen 2011-09-21 13:17 ` Michal Nazarewicz @ 2011-09-21 15:19 ` Michal Nazarewicz 2011-09-21 15:45 ` Dave Hansen 1 sibling, 1 reply; 46+ messages in thread From: Michal Nazarewicz @ 2011-09-21 15:19 UTC (permalink / raw) To: Marek Szyprowski, Dave Hansen Cc: linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig, Kyungmin Park, Russell King, Andrew Morton, KAMEZAWA Hiroyuki, Ankita Garg, Daniel Walker, Mel Gorman, Arnd Bergmann, Jesse Barker, Jonathan Corbet, Shariq Hasnain, Chunsang Jeong From: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Michal Nazarewicz <mina86@mina86.com> --- include/linux/page-isolation.h | 4 ++- mm/page_alloc.c | 66 ++++++++++++++++++++++++++++++++++----- 2 files changed, 60 insertions(+), 10 deletions(-) > On Fri, 2011-08-19 at 16:27 +0200, Marek Szyprowski wrote: >> +unsigned long alloc_contig_freed_pages(unsigned long start, unsigned >> long end, >> + gfp_t flag) >> +{ >> + unsigned long pfn = start, count; >> + struct page *page; >> + struct zone *zone; >> + int order; >> + >> + VM_BUG_ON(!pfn_valid(start)); >> + zone = page_zone(pfn_to_page(start)); On Thu, 08 Sep 2011 20:05:52 +0200, Dave Hansen <dave@linux.vnet.ibm.com> wrote: > This implies that start->end are entirely contained in a single zone. > What enforces that? If some higher layer enforces that, I think we > probably need at least a VM_BUG_ON() in here and a comment about who > enforces it. >> + spin_lock_irq(&zone->lock); >> + >> + page = pfn_to_page(pfn); >> + for (;;) { >> + VM_BUG_ON(page_count(page) || !PageBuddy(page)); >> + list_del(&page->lru); >> + order = page_order(page); >> + zone->free_area[order].nr_free--; >> + rmv_page_order(page); >> + __mod_zone_page_state(zone, NR_FREE_PAGES, -(1UL << order)); >> + pfn += 1 << order; >> + if (pfn >= end) >> + break; >> + VM_BUG_ON(!pfn_valid(pfn)); >> + page += 1 << order; >> + } > This 'struct page *'++ stuff is OK, but only for small, aligned areas. > For at least some of the sparsemem modes (non-VMEMMAP), you could walk > off of the end of the section_mem_map[] when you cross a MAX_ORDER > boundary. I'd feel a little bit more comfortable if pfn_to_page() was > being done each time, or only occasionally when you cross a section > boundary. Do the attached changes seem to make sense? I wanted to avoid calling pfn_to_page() each time as it seem fairly expensive in sparsemem and disctontig modes. At the same time, the macro trickery is so that users of sparsemem-vmemmap and flatmem won't have to pay the price. diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h index b2a81fd..003c52f 100644 --- a/include/linux/page-isolation.h +++ b/include/linux/page-isolation.h @@ -46,11 +46,13 @@ static inline void unset_migratetype_isolate(struct page *page) { __unset_migratetype_isolate(page, MIGRATE_MOVABLE); } + +/* The below functions must be run on a range from a single zone. */ extern unsigned long alloc_contig_freed_pages(unsigned long start, unsigned long end, gfp_t flag); extern int alloc_contig_range(unsigned long start, unsigned long end, gfp_t flags, unsigned migratetype); -extern void free_contig_pages(struct page *page, int nr_pages); +extern void free_contig_pages(unsigned long pfn, unsigned nr_pages); /* * For migration. diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 46e78d4..32fda5d 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5716,9 +5716,41 @@ out: spin_unlock_irqrestore(&zone->lock, flags); } +#if defined(CONFIG_FLATMEM) || defined(CONFIG_SPARSEMEM_VMEMMAP) + +/* + * In FLATMEM and CONFIG_SPARSEMEM_VMEMMAP we can safely increment the page + * pointer and get the same value as if we were to get by calling + * pfn_to_page() on incremented pfn counter. + */ +#define __contig_next_page(page, pageblock_left, pfn, increment) \ + ((page) + (increment)) + +#define __contig_first_page(pageblock_left, pfn) pfn_to_page(pfn) + +#else + +/* + * If we cross pageblock boundary, make sure we get a valid page pointer. If + * we are within pageblock, incrementing the pointer is good enough, and is + * a bit of an optimisation. + */ +#define __contig_next_page(page, pageblock_left, pfn, increment) \ + (likely((pageblock_left) -= (increment)) ? (page) + (increment) \ + : (((pageblock_left) = pageblock_nr_pages), pfn_to_page(pfn))) + +#define __contig_first_page(pageblock_left, pfn) ( \ + ((pageblock_left) = pageblock_nr_pages - \ + ((pfn) & (pageblock_nr_pages - 1))), \ + pfn_to_page(pfn)) + + +#endif + unsigned long alloc_contig_freed_pages(unsigned long start, unsigned long end, gfp_t flag) { + unsigned long pageblock_left __unused; unsigned long pfn = start, count; struct page *page; struct zone *zone; @@ -5729,27 +5761,37 @@ unsigned long alloc_contig_freed_pages(unsigned long start, unsigned long end, spin_lock_irq(&zone->lock); - page = pfn_to_page(pfn); + page = __contig_first_page(pageblock_left, pfn); for (;;) { - VM_BUG_ON(page_count(page) || !PageBuddy(page)); + VM_BUG_ON(!page_count(page) || !PageBuddy(page) || + page_zone(page) != zone); + list_del(&page->lru); order = page_order(page); + count = 1UL << order; zone->free_area[order].nr_free--; rmv_page_order(page); - __mod_zone_page_state(zone, NR_FREE_PAGES, -(1UL << order)); - pfn += 1 << order; + __mod_zone_page_state(zone, NR_FREE_PAGES, -(long)count); + + pfn += count; if (pfn >= end) break; VM_BUG_ON(!pfn_valid(pfn)); - page += 1 << order; + + page = __contig_next_page(page, pageblock_left, pfn, count); } spin_unlock_irq(&zone->lock); /* After this, pages in the range can be freed one be one */ - page = pfn_to_page(start); - for (count = pfn - start; count; --count, ++page) + count = pfn - start; + pfn = start; + page = __contig_first_page(pageblock_left, pfn); + for (; count; --count) { prep_new_page(page, 0, flag); + ++pfn; + page = __contig_next_page(page, pageblock_left, pfn, 1); + } return pfn; } @@ -5903,10 +5945,16 @@ done: return ret; } -void free_contig_pages(struct page *page, int nr_pages) +void free_contig_pages(unsigned long pfn, unsigned nr_pages) { - for (; nr_pages; --nr_pages, ++page) + unsigned long pageblock_left __unused; + struct page *page = __contig_first_page(pageblock_left, pfn); + + while (nr_pages--) { __free_page(page); + ++pfn; + page = __contig_next_page(page, pageblock_left, pfn, 1); + } } #ifdef CONFIG_MEMORY_HOTREMOVE -- 1.7.3.1 ^ permalink raw reply related [flat|nested] 46+ messages in thread
* Re: [PATCH 1/3] fixup! mm: alloc_contig_freed_pages() added 2011-09-21 15:19 ` [PATCH 1/3] fixup! " Michal Nazarewicz @ 2011-09-21 15:45 ` Dave Hansen 2011-09-21 16:26 ` Michal Nazarewicz 0 siblings, 1 reply; 46+ messages in thread From: Dave Hansen @ 2011-09-21 15:45 UTC (permalink / raw) To: Michal Nazarewicz Cc: Marek Szyprowski, linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig, Kyungmin Park, Russell King, Andrew Morton, KAMEZAWA Hiroyuki, Ankita Garg, Daniel Walker, Mel Gorman, Arnd Bergmann, Jesse Barker, Jonathan Corbet, Shariq Hasnain, Chunsang Jeong On Wed, 2011-09-21 at 17:19 +0200, Michal Nazarewicz wrote: > Do the attached changes seem to make sense? The logic looks OK. > I wanted to avoid calling pfn_to_page() each time as it seem fairly > expensive in sparsemem and disctontig modes. At the same time, the > macro trickery is so that users of sparsemem-vmemmap and flatmem won't > have to pay the price. Personally, I'd say the (incredibly minuscule) runtime cost is worth the cost of making folks' eyes bleed when they see those macros. I think there are some nicer ways to do it. Is there a reason you can't logically do? page = pfn_to_page(pfn); for (;;) { if (pfn_to_section_nr(pfn) == pfn_to_section_nr(pfn+1)) page++; else page = pfn_to_page(pfn+1); } pfn_to_section_nr() is a register shift. Our smallest section size on x86 is 128MB and on ppc64 16MB. So, at *WORST* (64k pages on ppc64), you're doing pfn_to_page() one of every 256 loops. My suggestion would be put put a macro up in the sparsemem headers that does something like: #ifdef VMEMMAP #define zone_pfn_same_memmap(pfn1, pfn2) (1) #elif SPARSEMEM_OTHER static inline int zone_pfn_same_memmap(unsigned long pfn1, unsigned long pfn2) { return (pfn_to_section_nr(pfn1) == pfn_to_section_nr(pfn2)); } #else #define zone_pfn_same_memmap(pfn1, pfn2) (1) #endif The zone_ bit is necessary in the naming because DISCONTIGMEM's pfns are at least contiguous within a zone. Only the non-VMEMMAP sparsemem case isn't. Other folks would probably have a use for something like that. Although most of the previous users have gotten to this point, given up, and just done pfn_to_page() on each loop. :) > +#if defined(CONFIG_FLATMEM) || defined(CONFIG_SPARSEMEM_VMEMMAP) > + > +/* > + * In FLATMEM and CONFIG_SPARSEMEM_VMEMMAP we can safely increment the page > + * pointer and get the same value as if we were to get by calling > + * pfn_to_page() on incremented pfn counter. > + */ > +#define __contig_next_page(page, pageblock_left, pfn, increment) \ > + ((page) + (increment)) > + > +#define __contig_first_page(pageblock_left, pfn) pfn_to_page(pfn) > + > +#else > + > +/* > + * If we cross pageblock boundary, make sure we get a valid page pointer. If > + * we are within pageblock, incrementing the pointer is good enough, and is > + * a bit of an optimisation. > + */ > +#define __contig_next_page(page, pageblock_left, pfn, increment) \ > + (likely((pageblock_left) -= (increment)) ? (page) + (increment) \ > + : (((pageblock_left) = pageblock_nr_pages), pfn_to_page(pfn))) > + > +#define __contig_first_page(pageblock_left, pfn) ( \ > + ((pageblock_left) = pageblock_nr_pages - \ > + ((pfn) & (pageblock_nr_pages - 1))), \ > + pfn_to_page(pfn)) > + > + > +#endif For the love of Pete, please make those in to functions if you're going to keep them. They're really unreadable like that. You might also want to look at mm/internal.h's mem_map_offset() and mem_map_next(). They're not _quite_ what you need, but they're close. -- Dave ^ permalink raw reply [flat|nested] 46+ messages in thread
* [PATCH 1/3] fixup! mm: alloc_contig_freed_pages() added 2011-09-21 15:45 ` Dave Hansen @ 2011-09-21 16:26 ` Michal Nazarewicz 2011-09-21 16:30 ` Dave Hansen 0 siblings, 1 reply; 46+ messages in thread From: Michal Nazarewicz @ 2011-09-21 16:26 UTC (permalink / raw) To: Marek Szyprowski, Dave Hansen Cc: linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig, Kyungmin Park, Russell King, Andrew Morton, KAMEZAWA Hiroyuki, Ankita Garg, Daniel Walker, Mel Gorman, Arnd Bergmann, Jesse Barker, Jonathan Corbet, Shariq Hasnain, Chunsang Jeong From: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Michal Nazarewicz <mina86@mina86.com> --- include/asm-generic/memory_model.h | 17 ++++++++++++++ include/linux/page-isolation.h | 4 ++- mm/page_alloc.c | 43 +++++++++++++++++++++++++++-------- 3 files changed, 53 insertions(+), 11 deletions(-) > On Wed, 2011-09-21 at 17:19 +0200, Michal Nazarewicz wrote: >> I wanted to avoid calling pfn_to_page() each time as it seem fairly >> expensive in sparsemem and disctontig modes. At the same time, the >> macro trickery is so that users of sparsemem-vmemmap and flatmem won't >> have to pay the price. On Wed, 21 Sep 2011 17:45:59 +0200, Dave Hansen <dave@linux.vnet.ibm.com> wrote: > Personally, I'd say the (incredibly minuscule) runtime cost is worth the > cost of making folks' eyes bleed when they see those macros. I think > there are some nicer ways to do it. Yeah. I wasn't amazed by them either. > Is there a reason you can't logically do? > page = pfn_to_page(pfn); > for (;;) { > if (pfn_to_section_nr(pfn) == pfn_to_section_nr(pfn+1)) > page++; > else > page = pfn_to_page(pfn+1); > } Done. Thanks for the suggestions! >> +#define __contig_next_page(page, pageblock_left, pfn, increment) \ >> + (likely((pageblock_left) -= (increment)) ? (page) + (increment) \ >> + : (((pageblock_left) = pageblock_nr_pages), pfn_to_page(pfn))) >> + >> +#define __contig_first_page(pageblock_left, pfn) ( \ >> + ((pageblock_left) = pageblock_nr_pages - \ >> + ((pfn) & (pageblock_nr_pages - 1))), \ >> + pfn_to_page(pfn)) >> + >> +#endif > For the love of Pete, please make those in to functions if you're going > to keep them. That was tricky because they modify pageblock_left. Not relevant now anyways though. diff --git a/include/asm-generic/memory_model.h b/include/asm-generic/memory_model.h index fb2d63f..900da88 100644 --- a/include/asm-generic/memory_model.h +++ b/include/asm-generic/memory_model.h @@ -69,6 +69,23 @@ }) #endif /* CONFIG_FLATMEM/DISCONTIGMEM/SPARSEMEM */ +#if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP) + +/* + * Both PFNs must be from the same zone! If this function returns + * true, pfn_to_page(pfn1) + (pfn2 - pfn1) == pfn_to_page(pfn2). + */ +static inline bool zone_pfn_same_memmap(unsigned long pfn1, unsigned long pfn2) +{ + return pfn_to_section_nr(pfn1) == pfn_to_section_nr(pfn2); +} + +#else + +#define zone_pfn_same_memmap(pfn1, pfn2) (true) + +#endif + #define page_to_pfn __page_to_pfn #define pfn_to_page __pfn_to_page diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h index b2a81fd..003c52f 100644 --- a/include/linux/page-isolation.h +++ b/include/linux/page-isolation.h @@ -46,11 +46,13 @@ static inline void unset_migratetype_isolate(struct page *page) { __unset_migratetype_isolate(page, MIGRATE_MOVABLE); } + +/* The below functions must be run on a range from a single zone. */ extern unsigned long alloc_contig_freed_pages(unsigned long start, unsigned long end, gfp_t flag); extern int alloc_contig_range(unsigned long start, unsigned long end, gfp_t flags, unsigned migratetype); -extern void free_contig_pages(struct page *page, int nr_pages); +extern void free_contig_pages(unsigned long pfn, unsigned nr_pages); /* * For migration. diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 46e78d4..bc200a9 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5725,31 +5725,46 @@ unsigned long alloc_contig_freed_pages(unsigned long start, unsigned long end, int order; VM_BUG_ON(!pfn_valid(start)); - zone = page_zone(pfn_to_page(start)); + page = pfn_to_page(start); + zone = page_zone(page); spin_lock_irq(&zone->lock); - page = pfn_to_page(pfn); for (;;) { - VM_BUG_ON(page_count(page) || !PageBuddy(page)); + VM_BUG_ON(!page_count(page) || !PageBuddy(page) || + page_zone(page) != zone); + list_del(&page->lru); order = page_order(page); + count = 1UL << order; zone->free_area[order].nr_free--; rmv_page_order(page); - __mod_zone_page_state(zone, NR_FREE_PAGES, -(1UL << order)); - pfn += 1 << order; + __mod_zone_page_state(zone, NR_FREE_PAGES, -(long)count); + + pfn += count; if (pfn >= end) break; VM_BUG_ON(!pfn_valid(pfn)); - page += 1 << order; + + if (zone_pfn_same_memmap(pfn - count, pfn)) + page += count; + else + page = pfn_to_page(pfn); } spin_unlock_irq(&zone->lock); /* After this, pages in the range can be freed one be one */ - page = pfn_to_page(start); - for (count = pfn - start; count; --count, ++page) + count = pfn - start; + pfn = start; + for (page = pfn_to_page(pfn); count; --count) { prep_new_page(page, 0, flag); + ++pfn; + if (likely(zone_pfn_same_memmap(pfn - 1, pfn))) + ++page; + else + page = pfn_to_page(pfn); + } return pfn; } @@ -5903,10 +5918,18 @@ done: return ret; } -void free_contig_pages(struct page *page, int nr_pages) +void free_contig_pages(unsigned long pfn, unsigned nr_pages) { - for (; nr_pages; --nr_pages, ++page) + struct page *page = pfn_to_page(pfn); + + while (nr_pages--) { __free_page(page); + ++pfn; + if (likely(zone_pfn_same_memmap(pfn - 1, pfn))) + ++page; + else + page = pfn_to_page(pfn); + } } #ifdef CONFIG_MEMORY_HOTREMOVE -- 1.7.3.1 ^ permalink raw reply related [flat|nested] 46+ messages in thread
* Re: [PATCH 1/3] fixup! mm: alloc_contig_freed_pages() added 2011-09-21 16:26 ` Michal Nazarewicz @ 2011-09-21 16:30 ` Dave Hansen 0 siblings, 0 replies; 46+ messages in thread From: Dave Hansen @ 2011-09-21 16:30 UTC (permalink / raw) To: Michal Nazarewicz Cc: Marek Szyprowski, linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig, Kyungmin Park, Russell King, Andrew Morton, KAMEZAWA Hiroyuki, Ankita Garg, Daniel Walker, Mel Gorman, Arnd Bergmann, Jesse Barker, Jonathan Corbet, Shariq Hasnain, Chunsang Jeong On Wed, 2011-09-21 at 18:26 +0200, Michal Nazarewicz wrote: > - page += 1 << order; > + > + if (zone_pfn_same_memmap(pfn - count, pfn)) > + page += count; > + else > + page = pfn_to_page(pfn); > } That all looks sane to me and should fix the bug I brought up. -- Dave ^ permalink raw reply [flat|nested] 46+ messages in thread
* [PATCH 3/8] mm: alloc_contig_range() added 2011-08-19 14:27 [PATCHv15 0/8] Contiguous Memory Allocator Marek Szyprowski 2011-08-19 14:27 ` [PATCH 1/8] mm: move some functions from memory_hotplug.c to page_isolation.c Marek Szyprowski 2011-08-19 14:27 ` [PATCH 2/8] mm: alloc_contig_freed_pages() added Marek Szyprowski @ 2011-08-19 14:27 ` Marek Szyprowski 2011-08-19 14:27 ` [PATCH 4/8] mm: MIGRATE_CMA migration type added Marek Szyprowski ` (4 subsequent siblings) 7 siblings, 0 replies; 46+ messages in thread From: Marek Szyprowski @ 2011-08-19 14:27 UTC (permalink / raw) To: linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig Cc: Michal Nazarewicz, Marek Szyprowski, Kyungmin Park, Russell King, Andrew Morton, KAMEZAWA Hiroyuki, Ankita Garg, Daniel Walker, Mel Gorman, Arnd Bergmann, Jesse Barker, Jonathan Corbet, Shariq Hasnain, Chunsang Jeong From: Michal Nazarewicz <m.nazarewicz@samsung.com> This commit adds the alloc_contig_range() function which tries to allecate given range of pages. It tries to migrate all already allocated pages that fall in the range thus freeing them. Once all pages in the range are freed they are removed from the buddy system thus allocated for the caller to use. Signed-off-by: Michal Nazarewicz <m.nazarewicz@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> [m.szyprowski: renamed some variables for easier code reading] Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> CC: Michal Nazarewicz <mina86@mina86.com> Acked-by: Arnd Bergmann <arnd@arndb.de> --- include/linux/page-isolation.h | 2 + mm/page_alloc.c | 144 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 146 insertions(+), 0 deletions(-) diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h index f1417ed..c5d1a7c 100644 --- a/include/linux/page-isolation.h +++ b/include/linux/page-isolation.h @@ -34,6 +34,8 @@ extern int set_migratetype_isolate(struct page *page); extern void unset_migratetype_isolate(struct page *page); extern unsigned long alloc_contig_freed_pages(unsigned long start, unsigned long end, gfp_t flag); +extern int alloc_contig_range(unsigned long start, unsigned long end, + gfp_t flags); extern void free_contig_pages(struct page *page, int nr_pages); /* diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ad6ae3f..35423c2 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5706,6 +5706,150 @@ unsigned long alloc_contig_freed_pages(unsigned long start, unsigned long end, return pfn; } +static unsigned long pfn_to_maxpage(unsigned long pfn) +{ + return pfn & ~(MAX_ORDER_NR_PAGES - 1); +} + +static unsigned long pfn_to_maxpage_up(unsigned long pfn) +{ + return ALIGN(pfn, MAX_ORDER_NR_PAGES); +} + +#define MIGRATION_RETRY 5 +static int __alloc_contig_migrate_range(unsigned long start, unsigned long end) +{ + int migration_failed = 0, ret; + unsigned long pfn = start; + + /* + * Some code "borrowed" from KAMEZAWA Hiroyuki's + * __alloc_contig_pages(). + */ + + for (;;) { + pfn = scan_lru_pages(pfn, end); + if (!pfn || pfn >= end) + break; + + ret = do_migrate_range(pfn, end); + if (!ret) { + migration_failed = 0; + } else if (ret != -EBUSY + || ++migration_failed >= MIGRATION_RETRY) { + return ret; + } else { + /* There are unstable pages.on pagevec. */ + lru_add_drain_all(); + /* + * there may be pages on pcplist before + * we mark the range as ISOLATED. + */ + drain_all_pages(); + } + cond_resched(); + } + + if (!migration_failed) { + /* drop all pages in pagevec and pcp list */ + lru_add_drain_all(); + drain_all_pages(); + } + + /* Make sure all pages are isolated */ + if (WARN_ON(test_pages_isolated(start, end))) + return -EBUSY; + + return 0; +} + +/** + * alloc_contig_range() -- tries to allocate given range of pages + * @start: start PFN to allocate + * @end: one-past-the-last PFN to allocate + * @flags: flags passed to alloc_contig_freed_pages(). + * + * The PFN range does not have to be pageblock or MAX_ORDER_NR_PAGES + * aligned, hovewer it's callers responsibility to guarantee that we + * are the only thread that changes migrate type of pageblocks the + * pages fall in. + * + * Returns zero on success or negative error code. On success all + * pages which PFN is in (start, end) are allocated for the caller and + * need to be freed with free_contig_pages(). + */ +int alloc_contig_range(unsigned long start, unsigned long end, + gfp_t flags) +{ + unsigned long outer_start, outer_end; + int ret; + + /* + * What we do here is we mark all pageblocks in range as + * MIGRATE_ISOLATE. Because of the way page allocator work, we + * align the range to MAX_ORDER pages so that page allocator + * won't try to merge buddies from different pageblocks and + * change MIGRATE_ISOLATE to some other migration type. + * + * Once the pageblocks are marked as MIGRATE_ISOLATE, we + * migrate the pages from an unaligned range (ie. pages that + * we are interested in). This will put all the pages in + * range back to page allocator as MIGRATE_ISOLATE. + * + * When this is done, we take the pages in range from page + * allocator removing them from the buddy system. This way + * page allocator will never consider using them. + * + * This lets us mark the pageblocks back as + * MIGRATE_CMA/MIGRATE_MOVABLE so that free pages in the + * MAX_ORDER aligned range but not in the unaligned, original + * range are put back to page allocator so that buddy can use + * them. + */ + + ret = start_isolate_page_range(pfn_to_maxpage(start), + pfn_to_maxpage_up(end)); + if (ret) + goto done; + + ret = __alloc_contig_migrate_range(start, end); + if (ret) + goto done; + + /* + * Pages from [start, end) are within a MAX_ORDER_NR_PAGES + * aligned blocks that are marked as MIGRATE_ISOLATE. What's + * more, all pages in [start, end) are free in page allocator. + * What we are going to do is to allocate all pages from + * [start, end) (that is remove them from page allocater). + * + * The only problem is that pages at the beginning and at the + * end of interesting range may be not aligned with pages that + * page allocator holds, ie. they can be part of higher order + * pages. Because of this, we reserve the bigger range and + * once this is done free the pages we are not interested in. + */ + + ret = 0; + while (!PageBuddy(pfn_to_page(start & (~0UL << ret)))) + if (WARN_ON(++ret >= MAX_ORDER)) + return -EINVAL; + + outer_start = start & (~0UL << ret); + outer_end = alloc_contig_freed_pages(outer_start, end, flags); + + /* Free head and tail (if any) */ + if (start != outer_start) + free_contig_pages(pfn_to_page(outer_start), start - outer_start); + if (end != outer_end) + free_contig_pages(pfn_to_page(end), outer_end - end); + + ret = 0; +done: + undo_isolate_page_range(pfn_to_maxpage(start), pfn_to_maxpage_up(end)); + return ret; +} + void free_contig_pages(struct page *page, int nr_pages) { for (; nr_pages; --nr_pages, ++page) -- 1.7.1.569.g6f426 ^ permalink raw reply related [flat|nested] 46+ messages in thread
* [PATCH 4/8] mm: MIGRATE_CMA migration type added 2011-08-19 14:27 [PATCHv15 0/8] Contiguous Memory Allocator Marek Szyprowski ` (2 preceding siblings ...) 2011-08-19 14:27 ` [PATCH 3/8] mm: alloc_contig_range() added Marek Szyprowski @ 2011-08-19 14:27 ` Marek Szyprowski 2011-08-19 14:27 ` [PATCH 5/8] mm: MIGRATE_CMA isolation functions added Marek Szyprowski ` (3 subsequent siblings) 7 siblings, 0 replies; 46+ messages in thread From: Marek Szyprowski @ 2011-08-19 14:27 UTC (permalink / raw) To: linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig Cc: Michal Nazarewicz, Marek Szyprowski, Kyungmin Park, Russell King, Andrew Morton, KAMEZAWA Hiroyuki, Ankita Garg, Daniel Walker, Mel Gorman, Arnd Bergmann, Jesse Barker, Jonathan Corbet, Shariq Hasnain, Chunsang Jeong From: Michal Nazarewicz <m.nazarewicz@samsung.com> The MIGRATE_CMA migration type has two main characteristics: (i) only movable pages can be allocated from MIGRATE_CMA pageblocks and (ii) page allocator will never change migration type of MIGRATE_CMA pageblocks. This guarantees that page in a MIGRATE_CMA page block can always be migrated somewhere else (unless there's no memory left in the system). It is designed to be used with Contiguous Memory Allocator (CMA) for allocating big chunks (eg. 10MiB) of physically contiguous memory. Once driver requests contiguous memory, CMA will migrate pages from MIGRATE_CMA pageblocks. To minimise number of migrations, MIGRATE_CMA migration type is the last type tried when page allocator falls back to other migration types then requested. Signed-off-by: Michal Nazarewicz <m.nazarewicz@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> [m.szyprowski: cleaned up Kconfig, renamed some functions, removed ifdefs] Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> CC: Michal Nazarewicz <mina86@mina86.com> Acked-by: Arnd Bergmann <arnd@arndb.de> --- include/linux/mmzone.h | 41 +++++++++++++++--- include/linux/page-isolation.h | 1 + mm/Kconfig | 8 +++- mm/compaction.c | 10 +++++ mm/page_alloc.c | 88 +++++++++++++++++++++++++++++++--------- 5 files changed, 120 insertions(+), 28 deletions(-) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index be1ac8d..74b7f27 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -35,13 +35,35 @@ */ #define PAGE_ALLOC_COSTLY_ORDER 3 -#define MIGRATE_UNMOVABLE 0 -#define MIGRATE_RECLAIMABLE 1 -#define MIGRATE_MOVABLE 2 -#define MIGRATE_PCPTYPES 3 /* the number of types on the pcp lists */ -#define MIGRATE_RESERVE 3 -#define MIGRATE_ISOLATE 4 /* can't allocate from here */ -#define MIGRATE_TYPES 5 +enum { + MIGRATE_UNMOVABLE, + MIGRATE_RECLAIMABLE, + MIGRATE_MOVABLE, + MIGRATE_PCPTYPES, /* the number of types on the pcp lists */ + MIGRATE_RESERVE = MIGRATE_PCPTYPES, + /* + * MIGRATE_CMA migration type is designed to mimic the way + * ZONE_MOVABLE works. Only movable pages can be allocated + * from MIGRATE_CMA pageblocks and page allocator never + * implicitly change migration type of MIGRATE_CMA pageblock. + * + * The way to use it is to change migratetype of a range of + * pageblocks to MIGRATE_CMA which can be done by + * __free_pageblock_cma() function. What is important though + * is that a range of pageblocks must be aligned to + * MAX_ORDER_NR_PAGES should biggest page be bigger then + * a single pageblock. + */ + MIGRATE_CMA, + MIGRATE_ISOLATE, /* can't allocate from here */ + MIGRATE_TYPES +}; + +#ifdef CONFIG_CMA_MIGRATE_TYPE +# define is_migrate_cma(migratetype) unlikely((migratetype) == MIGRATE_CMA) +#else +# define is_migrate_cma(migratetype) false +#endif #define for_each_migratetype_order(order, type) \ for (order = 0; order < MAX_ORDER; order++) \ @@ -54,6 +76,11 @@ static inline int get_pageblock_migratetype(struct page *page) return get_pageblock_flags_group(page, PB_migrate, PB_migrate_end); } +static inline bool is_pageblock_cma(struct page *page) +{ + return is_migrate_cma(get_pageblock_migratetype(page)); +} + struct free_area { struct list_head free_list[MIGRATE_TYPES]; unsigned long nr_free; diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h index c5d1a7c..856d9cf 100644 --- a/include/linux/page-isolation.h +++ b/include/linux/page-isolation.h @@ -46,4 +46,5 @@ int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn); unsigned long scan_lru_pages(unsigned long start, unsigned long end); int do_migrate_range(unsigned long start_pfn, unsigned long end_pfn); +extern void init_cma_reserved_pageblock(struct page *page); #endif diff --git a/mm/Kconfig b/mm/Kconfig index f2f1ca1..dd6e1ea 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -189,7 +189,7 @@ config COMPACTION config MIGRATION bool "Page migration" def_bool y - depends on NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION + depends on NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA_MIGRATE_TYPE help Allows the migration of the physical location of pages of processes while the virtual addresses are not changed. This is useful in @@ -198,6 +198,12 @@ config MIGRATION pages as migration can relocate pages to satisfy a huge page allocation instead of reclaiming. +config CMA_MIGRATE_TYPE + bool + help + This enables the use the MIGRATE_CMA migrate type, which lets lets CMA + work on almost arbitrary memory range and not only inside ZONE_MOVABLE. + config PHYS_ADDR_T_64BIT def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT diff --git a/mm/compaction.c b/mm/compaction.c index 6cc604b..9e5cc59 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -119,6 +119,16 @@ static bool suitable_migration_target(struct page *page) if (migratetype == MIGRATE_ISOLATE || migratetype == MIGRATE_RESERVE) return false; + /* Keep MIGRATE_CMA alone as well. */ + /* + * XXX Revisit. We currently cannot let compaction touch CMA + * pages since compaction insists on changing their migration + * type to MIGRATE_MOVABLE (see split_free_page() called from + * isolate_freepages_block() above). + */ + if (is_migrate_cma(migratetype)) + return false; + /* If the page is a large free page, then allow migration */ if (PageBuddy(page) && page_order(page) >= pageblock_order) return true; diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 35423c2..c9dfed0 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -719,6 +719,29 @@ void __meminit __free_pages_bootmem(struct page *page, unsigned int order) } } +#ifdef CONFIG_CMA_MIGRATE_TYPE +/* + * Free whole pageblock and set it's migration type to MIGRATE_CMA. + */ +void __init init_cma_reserved_pageblock(struct page *page) +{ + struct page *p = page; + unsigned i = pageblock_nr_pages; + + prefetchw(p); + do { + if (--i) + prefetchw(p + 1); + __ClearPageReserved(p); + set_page_count(p, 0); + } while (++p, i); + + set_page_refcounted(page); + set_pageblock_migratetype(page, MIGRATE_CMA); + __free_pages(page, pageblock_order); + totalram_pages += pageblock_nr_pages; +} +#endif /* * The order of subdivision here is critical for the IO subsystem. @@ -827,11 +850,11 @@ struct page *__rmqueue_smallest(struct zone *zone, unsigned int order, * This array describes the order lists are fallen back to when * the free lists for the desirable migrate type are depleted */ -static int fallbacks[MIGRATE_TYPES][MIGRATE_TYPES-1] = { +static int fallbacks[MIGRATE_TYPES][4] = { [MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE, MIGRATE_RESERVE }, [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE, MIGRATE_RESERVE }, - [MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_RESERVE }, - [MIGRATE_RESERVE] = { MIGRATE_RESERVE, MIGRATE_RESERVE, MIGRATE_RESERVE }, /* Never used */ + [MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_CMA , MIGRATE_RESERVE }, + [MIGRATE_RESERVE] = { MIGRATE_RESERVE }, /* Never used */ }; /* @@ -926,12 +949,12 @@ __rmqueue_fallback(struct zone *zone, int order, int start_migratetype) /* Find the largest possible block of pages in the other list */ for (current_order = MAX_ORDER-1; current_order >= order; --current_order) { - for (i = 0; i < MIGRATE_TYPES - 1; i++) { + for (i = 0; i < ARRAY_SIZE(fallbacks[0]); i++) { migratetype = fallbacks[start_migratetype][i]; /* MIGRATE_RESERVE handled later if necessary */ if (migratetype == MIGRATE_RESERVE) - continue; + break; area = &(zone->free_area[current_order]); if (list_empty(&area->free_list[migratetype])) @@ -946,19 +969,29 @@ __rmqueue_fallback(struct zone *zone, int order, int start_migratetype) * pages to the preferred allocation list. If falling * back for a reclaimable kernel allocation, be more * aggressive about taking ownership of free pages + * + * On the other hand, never change migration + * type of MIGRATE_CMA pageblocks nor move CMA + * pages on different free lists. We don't + * want unmovable pages to be allocated from + * MIGRATE_CMA areas. */ - if (unlikely(current_order >= (pageblock_order >> 1)) || - start_migratetype == MIGRATE_RECLAIMABLE || - page_group_by_mobility_disabled) { - unsigned long pages; + if (!is_pageblock_cma(page) && + (unlikely(current_order >= pageblock_order / 2) || + start_migratetype == MIGRATE_RECLAIMABLE || + page_group_by_mobility_disabled)) { + int pages; pages = move_freepages_block(zone, page, - start_migratetype); + start_migratetype); - /* Claim the whole block if over half of it is free */ + /* + * Claim the whole block if over half + * of it is free + */ if (pages >= (1 << (pageblock_order-1)) || - page_group_by_mobility_disabled) + page_group_by_mobility_disabled) set_pageblock_migratetype(page, - start_migratetype); + start_migratetype); migratetype = start_migratetype; } @@ -968,11 +1001,14 @@ __rmqueue_fallback(struct zone *zone, int order, int start_migratetype) rmv_page_order(page); /* Take ownership for orders >= pageblock_order */ - if (current_order >= pageblock_order) + if (current_order >= pageblock_order && + !is_pageblock_cma(page)) change_pageblock_range(page, current_order, start_migratetype); - expand(zone, page, order, current_order, area, migratetype); + expand(zone, page, order, current_order, area, + is_migrate_cma(start_migratetype) + ? start_migratetype : migratetype); trace_mm_page_alloc_extfrag(page, order, current_order, start_migratetype, migratetype); @@ -1044,7 +1080,10 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order, list_add(&page->lru, list); else list_add_tail(&page->lru, list); - set_page_private(page, migratetype); + if (is_pageblock_cma(page)) + set_page_private(page, MIGRATE_CMA); + else + set_page_private(page, migratetype); list = &page->lru; } __mod_zone_page_state(zone, NR_FREE_PAGES, -(i << order)); @@ -1185,9 +1224,16 @@ void free_hot_cold_page(struct page *page, int cold) * offlined but treat RESERVE as movable pages so we can get those * areas back if necessary. Otherwise, we may have to free * excessively into the page allocator + * + * Still, do not change migration type of MIGRATE_CMA pages (if + * they'd be recorded as MIGRATE_MOVABLE an unmovable page could + * be allocated from MIGRATE_CMA block and we don't want to allow + * that). In this respect, treat MIGRATE_CMA like + * MIGRATE_ISOLATE. */ if (migratetype >= MIGRATE_PCPTYPES) { - if (unlikely(migratetype == MIGRATE_ISOLATE)) { + if (unlikely(migratetype == MIGRATE_ISOLATE + || is_migrate_cma(migratetype))) { free_one_page(zone, page, 0, migratetype); goto out; } @@ -1276,7 +1322,9 @@ int split_free_page(struct page *page) if (order >= pageblock_order - 1) { struct page *endpage = page + (1 << order) - 1; for (; page < endpage; page += pageblock_nr_pages) - set_pageblock_migratetype(page, MIGRATE_MOVABLE); + if (!is_pageblock_cma(page)) + set_pageblock_migratetype(page, + MIGRATE_MOVABLE); } return 1 << order; @@ -5554,8 +5602,8 @@ __count_immobile_pages(struct zone *zone, struct page *page, int count) */ if (zone_idx(zone) == ZONE_MOVABLE) return true; - - if (get_pageblock_migratetype(page) == MIGRATE_MOVABLE) + if (get_pageblock_migratetype(page) == MIGRATE_MOVABLE || + is_pageblock_cma(page)) return true; pfn = page_to_pfn(page); -- 1.7.1.569.g6f426 ^ permalink raw reply related [flat|nested] 46+ messages in thread
* [PATCH 5/8] mm: MIGRATE_CMA isolation functions added 2011-08-19 14:27 [PATCHv15 0/8] Contiguous Memory Allocator Marek Szyprowski ` (3 preceding siblings ...) 2011-08-19 14:27 ` [PATCH 4/8] mm: MIGRATE_CMA migration type added Marek Szyprowski @ 2011-08-19 14:27 ` Marek Szyprowski 2011-08-19 14:27 ` [PATCH 6/8] drivers: add Contiguous Memory Allocator Marek Szyprowski ` (2 subsequent siblings) 7 siblings, 0 replies; 46+ messages in thread From: Marek Szyprowski @ 2011-08-19 14:27 UTC (permalink / raw) To: linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig Cc: Michal Nazarewicz, Marek Szyprowski, Kyungmin Park, Russell King, Andrew Morton, KAMEZAWA Hiroyuki, Ankita Garg, Daniel Walker, Mel Gorman, Arnd Bergmann, Jesse Barker, Jonathan Corbet, Shariq Hasnain, Chunsang Jeong From: Michal Nazarewicz <m.nazarewicz@samsung.com> This commit changes various functions that change pages and pageblocks migrate type between MIGRATE_ISOLATE and MIGRATE_MOVABLE in such a way as to allow to work with MIGRATE_CMA migrate type. Signed-off-by: Michal Nazarewicz <m.nazarewicz@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> CC: Michal Nazarewicz <mina86@mina86.com> Acked-by: Arnd Bergmann <arnd@arndb.de> --- include/linux/page-isolation.h | 40 +++++++++++++++++++++++++++------------- mm/page_alloc.c | 19 ++++++++++++------- mm/page_isolation.c | 15 ++++++++------- 3 files changed, 47 insertions(+), 27 deletions(-) diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h index 856d9cf..b2a81fd 100644 --- a/include/linux/page-isolation.h +++ b/include/linux/page-isolation.h @@ -3,39 +3,53 @@ /* * Changes migrate type in [start_pfn, end_pfn) to be MIGRATE_ISOLATE. - * If specified range includes migrate types other than MOVABLE, + * If specified range includes migrate types other than MOVABLE or CMA, * this will fail with -EBUSY. * * For isolating all pages in the range finally, the caller have to * free all pages in the range. test_page_isolated() can be used for * test it. */ -extern int -start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn); +int __start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, + unsigned migratetype); + +static inline int +start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn) +{ + return __start_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE); +} + +int __undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, + unsigned migratetype); /* * Changes MIGRATE_ISOLATE to MIGRATE_MOVABLE. * target range is [start_pfn, end_pfn) */ -extern int -undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn); +static inline int +undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn) +{ + return __undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE); +} /* - * test all pages in [start_pfn, end_pfn)are isolated or not. + * Test all pages in [start_pfn, end_pfn) are isolated or not. */ -extern int -test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn); +int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn); /* - * Internal funcs.Changes pageblock's migrate type. - * Please use make_pagetype_isolated()/make_pagetype_movable(). + * Internal functions. Changes pageblock's migrate type. */ -extern int set_migratetype_isolate(struct page *page); -extern void unset_migratetype_isolate(struct page *page); +int set_migratetype_isolate(struct page *page); +void __unset_migratetype_isolate(struct page *page, unsigned migratetype); +static inline void unset_migratetype_isolate(struct page *page) +{ + __unset_migratetype_isolate(page, MIGRATE_MOVABLE); +} extern unsigned long alloc_contig_freed_pages(unsigned long start, unsigned long end, gfp_t flag); extern int alloc_contig_range(unsigned long start, unsigned long end, - gfp_t flags); + gfp_t flags, unsigned migratetype); extern void free_contig_pages(struct page *page, int nr_pages); /* diff --git a/mm/page_alloc.c b/mm/page_alloc.c index c9dfed0..46e78d4 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5702,7 +5702,7 @@ out: return ret; } -void unset_migratetype_isolate(struct page *page) +void __unset_migratetype_isolate(struct page *page, unsigned migratetype) { struct zone *zone; unsigned long flags; @@ -5710,8 +5710,8 @@ void unset_migratetype_isolate(struct page *page) spin_lock_irqsave(&zone->lock, flags); if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE) goto out; - set_pageblock_migratetype(page, MIGRATE_MOVABLE); - move_freepages_block(zone, page, MIGRATE_MOVABLE); + set_pageblock_migratetype(page, migratetype); + move_freepages_block(zone, page, migratetype); out: spin_unlock_irqrestore(&zone->lock, flags); } @@ -5816,6 +5816,10 @@ static int __alloc_contig_migrate_range(unsigned long start, unsigned long end) * @start: start PFN to allocate * @end: one-past-the-last PFN to allocate * @flags: flags passed to alloc_contig_freed_pages(). + * @migratetype: migratetype of the underlaying pageblocks (either + * #MIGRATE_MOVABLE or #MIGRATE_CMA). All pageblocks + * in range must have the same migratetype and it must + * be either of the two. * * The PFN range does not have to be pageblock or MAX_ORDER_NR_PAGES * aligned, hovewer it's callers responsibility to guarantee that we @@ -5827,7 +5831,7 @@ static int __alloc_contig_migrate_range(unsigned long start, unsigned long end) * need to be freed with free_contig_pages(). */ int alloc_contig_range(unsigned long start, unsigned long end, - gfp_t flags) + gfp_t flags, unsigned migratetype) { unsigned long outer_start, outer_end; int ret; @@ -5855,8 +5859,8 @@ int alloc_contig_range(unsigned long start, unsigned long end, * them. */ - ret = start_isolate_page_range(pfn_to_maxpage(start), - pfn_to_maxpage_up(end)); + ret = __start_isolate_page_range(pfn_to_maxpage(start), + pfn_to_maxpage_up(end), migratetype); if (ret) goto done; @@ -5894,7 +5898,8 @@ int alloc_contig_range(unsigned long start, unsigned long end, ret = 0; done: - undo_isolate_page_range(pfn_to_maxpage(start), pfn_to_maxpage_up(end)); + __undo_isolate_page_range(pfn_to_maxpage(start), pfn_to_maxpage_up(end), + migratetype); return ret; } diff --git a/mm/page_isolation.c b/mm/page_isolation.c index 270a026..e232b25 100644 --- a/mm/page_isolation.c +++ b/mm/page_isolation.c @@ -23,10 +23,11 @@ __first_valid_page(unsigned long pfn, unsigned long nr_pages) } /* - * start_isolate_page_range() -- make page-allocation-type of range of pages + * __start_isolate_page_range() -- make page-allocation-type of range of pages * to be MIGRATE_ISOLATE. * @start_pfn: The lower PFN of the range to be isolated. * @end_pfn: The upper PFN of the range to be isolated. + * @migratetype: migrate type to set in error recovery. * * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in * the range will never be allocated. Any free pages and pages freed in the @@ -35,8 +36,8 @@ __first_valid_page(unsigned long pfn, unsigned long nr_pages) * start_pfn/end_pfn must be aligned to pageblock_order. * Returns 0 on success and -EBUSY if any part of range cannot be isolated. */ -int -start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn) +int __start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, + unsigned migratetype) { unsigned long pfn; unsigned long undo_pfn; @@ -59,7 +60,7 @@ undo: for (pfn = start_pfn; pfn < undo_pfn; pfn += pageblock_nr_pages) - unset_migratetype_isolate(pfn_to_page(pfn)); + __unset_migratetype_isolate(pfn_to_page(pfn), migratetype); return -EBUSY; } @@ -67,8 +68,8 @@ undo: /* * Make isolated pages available again. */ -int -undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn) +int __undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, + unsigned migratetype) { unsigned long pfn; struct page *page; @@ -80,7 +81,7 @@ undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn) page = __first_valid_page(pfn, pageblock_nr_pages); if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE) continue; - unset_migratetype_isolate(page); + __unset_migratetype_isolate(page, migratetype); } return 0; } -- 1.7.1.569.g6f426 ^ permalink raw reply related [flat|nested] 46+ messages in thread
* [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-08-19 14:27 [PATCHv15 0/8] Contiguous Memory Allocator Marek Szyprowski ` (4 preceding siblings ...) 2011-08-19 14:27 ` [PATCH 5/8] mm: MIGRATE_CMA isolation functions added Marek Szyprowski @ 2011-08-19 14:27 ` Marek Szyprowski 2011-08-19 14:27 ` [PATCH 7/8] ARM: integrate CMA with DMA-mapping subsystem Marek Szyprowski 2011-08-19 14:27 ` [PATCH 8/8] ARM: S5PV210: example of CMA private area for FIMC device on Goni board Marek Szyprowski 7 siblings, 0 replies; 46+ messages in thread From: Marek Szyprowski @ 2011-08-19 14:27 UTC (permalink / raw) To: linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig Cc: Michal Nazarewicz, Marek Szyprowski, Kyungmin Park, Russell King, Andrew Morton, KAMEZAWA Hiroyuki, Ankita Garg, Daniel Walker, Mel Gorman, Arnd Bergmann, Jesse Barker, Jonathan Corbet, Shariq Hasnain, Chunsang Jeong The Contiguous Memory Allocator is a set of helper functions for DMA mapping framework that improves allocations of contiguous memory chunks. CMA grabs memory on system boot, marks it with CMA_MIGRATE_TYPE and gives back to the system. Kernel is allowed to allocate movable pages within CMA's managed memory so that it can be used for example for page cache when DMA mapping do not use it. On dma_alloc_from_contiguous() request such pages are migrated out of CMA area to free required contiguous block and fulfill the request. This allows to allocate large contiguous chunks of memory at any time assuming that there is enough free memory available in the system. This code is heavily based on earlier works by Michal Nazarewicz. Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> CC: Michal Nazarewicz <mina86@mina86.com> --- arch/Kconfig | 3 + drivers/base/Kconfig | 79 ++++++++ drivers/base/Makefile | 1 + drivers/base/dma-contiguous.c | 386 ++++++++++++++++++++++++++++++++++++++++ include/linux/dma-contiguous.h | 102 +++++++++++ 5 files changed, 571 insertions(+), 0 deletions(-) create mode 100644 drivers/base/dma-contiguous.c create mode 100644 include/linux/dma-contiguous.h diff --git a/arch/Kconfig b/arch/Kconfig index 4b0669c..a3b39a2 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -124,6 +124,9 @@ config HAVE_ARCH_TRACEHOOK config HAVE_DMA_ATTRS bool +config HAVE_DMA_CONTIGUOUS + bool + config USE_GENERIC_SMP_HELPERS bool diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig index 21cf46f..bffe7fb 100644 --- a/drivers/base/Kconfig +++ b/drivers/base/Kconfig @@ -174,4 +174,83 @@ config SYS_HYPERVISOR source "drivers/base/regmap/Kconfig" +config CMA + bool "Contiguous Memory Allocator" + depends on HAVE_DMA_CONTIGUOUS && HAVE_MEMBLOCK + select MIGRATION + select CMA_MIGRATE_TYPE + help + This enables the Contiguous Memory Allocator which allows drivers + to allocate big physically-contiguous blocks of memory for use with + hardware components that do not support I/O map nor scatter-gather. + + For more information see <include/linux/dma-contiguous.h>. + If unsure, say "n". + +if CMA + +config CMA_DEBUG + bool "CMA debug messages (DEVELOPEMENT)" + help + Turns on debug messages in CMA. This produces KERN_DEBUG + messages for every CMA call as well as various messages while + processing calls such as dma_alloc_from_contiguous(). + This option does not affect warning and error messages. + +comment "Default contiguous memory area size:" + +config CMA_SIZE_ABSOLUTE + int "Absolute size (in MiB)" + depends on !CMA_SIZE_SEL_PERCENTAGE + default 16 + help + Defines the size (in MiB) of the default memory area for Contiguous + Memory Allocator. + +config CMA_SIZE_PERCENTAGE + int "Percentage of total memory" + depends on !CMA_SIZE_SEL_ABSOLUTE + default 10 + help + Defines the size of the default memory area for Contiguous Memory + Allocator as a percentage of the total memory in the system. + +choice + prompt "Selected region size" + default CMA_SIZE_SEL_ABSOLUTE + +config CMA_SIZE_SEL_ABSOLUTE + bool "Use absolute value only" + +config CMA_SIZE_SEL_PERCENTAGE + bool "Use percentage value only" + +config CMA_SIZE_SEL_MIN + bool "Use lower value (minimum)" + +config CMA_SIZE_SEL_MAX + bool "Use higher value (maximum)" + +endchoice + +config CMA_ALIGNMENT + int "Maximum PAGE_SIZE order of alignment for contiguous buffers" + range 4 9 + default 8 + help + DMA mapping framework by default aligns all buffers to the smallest + PAGE_SIZE order which is greater than or equal to the requested buffer + size. This works well for buffers up to a few hundreds kilobytes, but + for larger buffers it just a memory waste. With this parameter you can + specify the maximum PAGE_SIZE order for contiguous buffers. Larger + buffers will be aligned only to this specified order. The order is + expressed as a power of two multiplied by the PAGE_SIZE. + + For example, if your system defaults to 4KiB pages, the order value + of 8 means that the buffers will be aligned up to 1MiB only. + + If unsure, leave the default value "8". + +endif + endmenu diff --git a/drivers/base/Makefile b/drivers/base/Makefile index 99a375a..794546f 100644 --- a/drivers/base/Makefile +++ b/drivers/base/Makefile @@ -5,6 +5,7 @@ obj-y := core.o sys.o bus.o dd.o syscore.o \ cpu.o firmware.o init.o map.o devres.o \ attribute_container.o transport_class.o obj-$(CONFIG_DEVTMPFS) += devtmpfs.o +obj-$(CONFIG_CMA) += dma-contiguous.o obj-y += power/ obj-$(CONFIG_HAS_DMA) += dma-mapping.o obj-$(CONFIG_HAVE_GENERIC_DMA_COHERENT) += dma-coherent.o diff --git a/drivers/base/dma-contiguous.c b/drivers/base/dma-contiguous.c new file mode 100644 index 0000000..1f2519d --- /dev/null +++ b/drivers/base/dma-contiguous.c @@ -0,0 +1,386 @@ +/* + * Contiguous Memory Allocator for DMA mapping framework + * Copyright (c) 2010-2011 by Samsung Electronics. + * Written by: + * Marek Szyprowski <m.szyprowski@samsung.com> + * Michal Nazarewicz <mina86@mina86.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of the + * License or (at your optional) any later version of the license. + */ + +#define pr_fmt(fmt) "cma: " fmt + +#ifdef CONFIG_CMA_DEBUG +#ifndef DEBUG +# define DEBUG +#endif +#endif + +#include <asm/page.h> +#include <asm/dma-contiguous.h> + +#include <linux/memblock.h> +#include <linux/err.h> +#include <linux/mm.h> +#include <linux/mutex.h> +#include <linux/page-isolation.h> +#include <linux/slab.h> +#include <linux/swap.h> +#include <linux/mm_types.h> +#include <linux/dma-contiguous.h> + +#ifndef SZ_1M +#define SZ_1M (1 << 20) +#endif + +#ifdef phys_to_pfn +/* nothing to do */ +#elif defined __phys_to_pfn +# define phys_to_pfn __phys_to_pfn +#elif defined PFN_PHYS +# define phys_to_pfn PFN_PHYS +#else +# error correct phys_to_pfn implementation needed +#endif + +struct cma { + unsigned long base_pfn; + unsigned long count; + unsigned long *bitmap; +}; + +struct cma *dma_contiguous_default_area; + +#ifndef CONFIG_CMA_SIZE_ABSOLUTE +#define CONFIG_CMA_SIZE_ABSOLUTE 0 +#endif + +#ifndef CONFIG_CMA_SIZE_PERCENTAGE +#define CONFIG_CMA_SIZE_PERCENTAGE 0 +#endif + +static unsigned long size_abs = CONFIG_CMA_SIZE_ABSOLUTE * SZ_1M; +static unsigned long size_percent = CONFIG_CMA_SIZE_PERCENTAGE; +static long size_cmdline = -1; + +static int __init early_cma(char *p) +{ + pr_debug("%s(%s)\n", __func__, p); + size_cmdline = memparse(p, &p); + return 0; +} +early_param("cma", early_cma); + +static unsigned long __init __cma_early_get_total_pages(void) +{ + struct memblock_region *reg; + unsigned long total_pages = 0; + + /* + * We cannot use memblock_phys_mem_size() here, because + * memblock_analyze() has not been called yet. + */ + for_each_memblock(memory, reg) + total_pages += memblock_region_memory_end_pfn(reg) - + memblock_region_memory_base_pfn(reg); + return total_pages; +} + +/** + * dma_contiguous_reserve() - reserve area for contiguous memory handling + * + * This funtion reserves memory from early allocator. It should be + * called by arch specific code once the early allocator (memblock or bootmem) + * has been activated and all other subsystems have already allocated/reserved + * memory. + */ +void __init dma_contiguous_reserve(phys_addr_t limit) +{ + unsigned long selected_size = 0; + unsigned long total_pages; + + pr_debug("%s(limit %08lx)\n", __func__, (unsigned long)limit); + + total_pages = __cma_early_get_total_pages(); + size_percent *= (total_pages << PAGE_SHIFT) / 100; + + pr_debug("%s: total available: %ld MiB, size absolute: %ld MiB, size percentage: %ld MiB\n", + __func__, (total_pages << PAGE_SHIFT) / SZ_1M, + size_abs / SZ_1M, size_percent / SZ_1M); + +#ifdef CONFIG_CMA_SIZE_SEL_ABSOLUTE + selected_size = size_abs; +#elif defined(CONFIG_CMA_SIZE_SEL_PERCENTAGE) + selected_size = size_percent; +#elif defined(CONFIG_CMA_SIZE_SEL_MIN) + selected_size = min(size_abs, size_percent); +#elif defined(CONFIG_CMA_SIZE_SEL_MAX) + selected_size = max(size_abs, size_percent); +#endif + + if (size_cmdline != -1) + selected_size = size_cmdline; + + if (!selected_size) + return; + + pr_debug("%s: reserving %ld MiB for global area\n", __func__, + selected_size / SZ_1M); + + dma_declare_contiguous(NULL, selected_size, 0, limit); +}; + +static DEFINE_MUTEX(cma_mutex); + +static void __cma_activate_area(unsigned long base_pfn, unsigned long count) +{ + unsigned long pfn = base_pfn; + unsigned i = count >> pageblock_order; + struct zone *zone; + + VM_BUG_ON(!pfn_valid(pfn)); + zone = page_zone(pfn_to_page(pfn)); + + do { + unsigned j; + base_pfn = pfn; + for (j = pageblock_nr_pages; j; --j, pfn++) { + VM_BUG_ON(!pfn_valid(pfn)); + VM_BUG_ON(page_zone(pfn_to_page(pfn)) != zone); + } + init_cma_reserved_pageblock(pfn_to_page(base_pfn)); + } while (--i); +} + +static struct cma *__cma_create_area(unsigned long base_pfn, + unsigned long count) +{ + int bitmap_size = BITS_TO_LONGS(count) * sizeof(long); + struct cma *cma; + + pr_debug("%s(base %08lx, count %lx)\n", __func__, base_pfn, count); + + cma = kmalloc(sizeof *cma, GFP_KERNEL); + if (!cma) + return ERR_PTR(-ENOMEM); + + cma->base_pfn = base_pfn; + cma->count = count; + cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL); + + if (!cma->bitmap) + goto no_mem; + + __cma_activate_area(base_pfn, count); + + pr_debug("%s: returned %p\n", __func__, (void *)cma); + return cma; + +no_mem: + kfree(cma); + return ERR_PTR(-ENOMEM); +} + +static struct cma_reserved { + phys_addr_t start; + unsigned long size; + struct device *dev; +} cma_reserved[MAX_CMA_AREAS] __initdata; +static unsigned cma_reserved_count __initdata; + +static int __init __cma_init_reserved_areas(void) +{ + struct cma_reserved *r = cma_reserved; + unsigned i = cma_reserved_count; + + pr_debug("%s()\n", __func__); + + for (; i; --i, ++r) { + struct cma *cma; + cma = __cma_create_area(phys_to_pfn(r->start), + r->size >> PAGE_SHIFT); + if (!IS_ERR(cma)) { + if (r->dev) + set_dev_cma_area(r->dev, cma); + else + dma_contiguous_default_area = cma; + } + } + return 0; +} +core_initcall(__cma_init_reserved_areas); + +/** + * dma_declare_contiguous() - reserve area for contiguous memory handling + * for particular device + * @dev: Pointer to device structure. + * @size: Size of the reserved memory. + * @start: Start address of the reserved memory (optional, 0 for any). + * @limit: End address of the reserved memory (optional, 0 for any). + * + * This funtion reserves memory for specified device. It should be + * called by board specific code when early allocator (memblock or bootmem) + * is still activate. + */ +int __init dma_declare_contiguous(struct device *dev, unsigned long size, + phys_addr_t base, phys_addr_t limit) +{ + struct cma_reserved *r = &cma_reserved[cma_reserved_count]; + unsigned long alignment; + + pr_debug("%s(size %lx, base %08lx, limit %08lx)\n", __func__, + (unsigned long)size, (unsigned long)base, + (unsigned long)limit); + + /* Sanity checks */ + if (cma_reserved_count == ARRAY_SIZE(cma_reserved)) + return -ENOSPC; + + if (!size) + return -EINVAL; + + /* Sanitise input arguments */ + alignment = PAGE_SIZE << max(MAX_ORDER, pageblock_order); + base = ALIGN(base, alignment); + size = ALIGN(size, alignment); + limit = ALIGN(limit, alignment); + + /* Reserve memory */ + if (base) { + if (memblock_is_region_reserved(base, size) || + memblock_reserve(base, size) < 0) { + base = -EBUSY; + goto err; + } + } else { + /* + * Use __memblock_alloc_base() since + * memblock_alloc_base() panic()s. + */ + phys_addr_t addr = __memblock_alloc_base(size, alignment, limit); + if (!addr) { + base = -ENOMEM; + goto err; + } else if (addr + size > ~(unsigned long)0) { + memblock_free(addr, size); + base = -EOVERFLOW; + goto err; + } else { + base = addr; + } + } + + /* + * Each reserved area must be initialised later, when more kernel + * subsystems (like slab allocator) are available. + */ + r->start = base; + r->size = size; + r->dev = dev; + cma_reserved_count++; + printk(KERN_INFO "CMA: reserved %ld MiB at %08lx\n", size / SZ_1M, + (unsigned long)base); + + /* + * Architecture specific contiguous memory fixup. + */ + dma_contiguous_early_fixup(base, size); + return 0; +err: + printk(KERN_ERR "CMA: failed to reserve %ld MiB\n", size / SZ_1M); + return base; +} + +/** + * dma_alloc_from_contiguous() - allocate pages from contiguous area + * @dev: Pointer to device for which the allocation is performed. + * @count: Requested number of pages. + * @align: Requested alignment of pages (in PAGE_SIZE order). + * + * This funtion allocates memory buffer for specified device. It uses + * device specific contiguous memory area if available or the default + * global one. Requires architecture specific get_dev_cma_area() helper + * function. + */ +struct page *dma_alloc_from_contiguous(struct device *dev, int count, + unsigned int align) +{ + struct cma *cma = get_dev_cma_area(dev); + unsigned long pfn, pageno; + int ret; + + if (!cma) + return NULL; + + if (align > CONFIG_CMA_ALIGNMENT) + align = CONFIG_CMA_ALIGNMENT; + + pr_debug("%s(cma %p, count %d, align %d)\n", __func__, (void *)cma, + count, align); + + if (!count) + return NULL; + + mutex_lock(&cma_mutex); + + pageno = bitmap_find_next_zero_area(cma->bitmap, cma->count, 0, count, + (1 << align) - 1); + if (pageno >= cma->count) { + ret = -ENOMEM; + goto error; + } + bitmap_set(cma->bitmap, pageno, count); + + pfn = cma->base_pfn + pageno; + ret = alloc_contig_range(pfn, pfn + count, 0, MIGRATE_CMA); + if (ret) + goto free; + + mutex_unlock(&cma_mutex); + + pr_debug("%s(): returned %p\n", __func__, pfn_to_page(pfn)); + return pfn_to_page(pfn); +free: + bitmap_clear(cma->bitmap, pageno, count); +error: + mutex_unlock(&cma_mutex); + return NULL; +} + +/** + * dma_release_from_contiguous() - release allocated pages + * @dev: Pointer to device for which the pages were allocated. + * @pages: Allocated pages. + * @count: Number of allocated pages. + * + * This funtion releases memory allocated by dma_alloc_from_contiguous(). + * It return 0 when provided pages doen't belongs to contiguous area and + * 1 on success. + */ +int dma_release_from_contiguous(struct device *dev, struct page *pages, + int count) +{ + struct cma *cma = get_dev_cma_area(dev); + unsigned long pfn; + + if (!cma || !pages) + return 0; + + pr_debug("%s(page %p)\n", __func__, (void *)pages); + + pfn = page_to_pfn(pages); + + if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count) + return 0; + + mutex_lock(&cma_mutex); + + bitmap_clear(cma->bitmap, pfn - cma->base_pfn, count); + free_contig_pages(pages, count); + + mutex_unlock(&cma_mutex); + return 1; +} diff --git a/include/linux/dma-contiguous.h b/include/linux/dma-contiguous.h new file mode 100644 index 0000000..905773e --- /dev/null +++ b/include/linux/dma-contiguous.h @@ -0,0 +1,102 @@ +#ifndef __LINUX_CMA_H +#define __LINUX_CMA_H + +/* + * Contiguous Memory Allocator for DMA mapping framework + * Copyright (c) 2010-2011 by Samsung Electronics. + * Written by: + * Marek Szyprowski <m.szyprowski@samsung.com> + * Michal Nazarewicz <mina86@mina86.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of the + * License or (at your optional) any later version of the license. + */ + +/* + * Contiguous Memory Allocator + * + * The Contiguous Memory Allocator (CMA) makes it possible to + * allocate big contiguous chunks of memory after the system has + * booted. + * + * Why is it needed? + * + * Various devices on embedded systems have no scatter-getter and/or + * IO map support and require contiguous blocks of memory to + * operate. They include devices such as cameras, hardware video + * coders, etc. + * + * Such devices often require big memory buffers (a full HD frame + * is, for instance, more then 2 mega pixels large, i.e. more than 6 + * MB of memory), which makes mechanisms such as kmalloc() or + * alloc_page() ineffective. + * + * At the same time, a solution where a big memory region is + * reserved for a device is suboptimal since often more memory is + * reserved then strictly required and, moreover, the memory is + * inaccessible to page system even if device drivers don't use it. + * + * CMA tries to solve this issue by operating on memory regions + * where only movable pages can be allocated from. This way, kernel + * can use the memory for pagecache and when device driver requests + * it, allocated pages can be migrated. + * + * Driver usage + * + * CMA should not be used by the device drivers directly. It is + * only a helper framework for dma-mapping subsystem. + * + * For more information, see kernel-docs in drivers/base/dma-contiguous.c + */ + +#ifdef __KERNEL__ + +struct cma; +struct page; +struct device; + +#ifdef CONFIG_CMA + +extern struct cma *dma_contiguous_default_area; + +void dma_contiguous_reserve(phys_addr_t addr_limit); +int dma_declare_contiguous(struct device *dev, unsigned long size, + phys_addr_t base, phys_addr_t limit); + +struct page *dma_alloc_from_contiguous(struct device *dev, int count, + unsigned int order); +int dma_release_from_contiguous(struct device *dev, struct page *pages, + int count); + +#else + +static inline void dma_contiguous_reserve(phys_addr_t limit) { } + +static inline +int dma_declare_contiguous(struct device *dev, unsigned long size, + phys_addr_t base, phys_addr_t limit) +{ + return -ENOSYS; +} + +static inline +struct page *dma_alloc_from_contiguous(struct device *dev, int count, + unsigned int order) +{ + return NULL; +} + +static inline +int dma_release_from_contiguous(struct device *dev, struct page *pages, + int count) +{ + return 0; +} + +#endif + +#endif + +#endif -- 1.7.1.569.g6f426 ^ permalink raw reply related [flat|nested] 46+ messages in thread
* [PATCH 7/8] ARM: integrate CMA with DMA-mapping subsystem 2011-08-19 14:27 [PATCHv15 0/8] Contiguous Memory Allocator Marek Szyprowski ` (5 preceding siblings ...) 2011-08-19 14:27 ` [PATCH 6/8] drivers: add Contiguous Memory Allocator Marek Szyprowski @ 2011-08-19 14:27 ` Marek Szyprowski [not found] ` <CAMjpGUch=ogFQwBLqOukKVnyh60600jw5tMq-KYeNGSZ2PLQpA@mail.gmail.com> 2011-08-19 14:27 ` [PATCH 8/8] ARM: S5PV210: example of CMA private area for FIMC device on Goni board Marek Szyprowski 7 siblings, 1 reply; 46+ messages in thread From: Marek Szyprowski @ 2011-08-19 14:27 UTC (permalink / raw) To: linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig Cc: Michal Nazarewicz, Marek Szyprowski, Kyungmin Park, Russell King, Andrew Morton, KAMEZAWA Hiroyuki, Ankita Garg, Daniel Walker, Mel Gorman, Arnd Bergmann, Jesse Barker, Jonathan Corbet, Shariq Hasnain, Chunsang Jeong This patch adds support for CMA to dma-mapping subsystem for ARM architecture. By default a global CMA area is used, but specific devices are allowed to have their private memory areas if required (they can be created with dma_declare_contiguous() function during board initialization). Contiguous memory areas reserved for DMA are remapped with 2-level page tables on boot. Once a buffer is requested, a low memory kernel mapping is updated to to match requested memory access type. GFP_ATOMIC allocations are performed from special pool which is created early during boot. This way remapping page attributes is not needed on allocation time. CMA has been enabled unconditionally for ARMv6+ systems. Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> --- arch/arm/Kconfig | 2 + arch/arm/include/asm/device.h | 3 + arch/arm/include/asm/dma-contiguous.h | 33 +++ arch/arm/include/asm/mach/map.h | 1 + arch/arm/mm/dma-mapping.c | 362 +++++++++++++++++++++++++++------ arch/arm/mm/init.c | 8 + arch/arm/mm/mm.h | 3 + arch/arm/mm/mmu.c | 29 ++- 8 files changed, 366 insertions(+), 75 deletions(-) create mode 100644 arch/arm/include/asm/dma-contiguous.h diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 5ebc5d9..2327fdd 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -3,6 +3,8 @@ config ARM default y select HAVE_AOUT select HAVE_DMA_API_DEBUG + select HAVE_DMA_CONTIGUOUS if (CPU_V6 || CPU_V6K || CPU_V7) + select CMA if (CPU_V6 || CPU_V6K || CPU_V7) select HAVE_IDE select HAVE_MEMBLOCK select RTC_LIB diff --git a/arch/arm/include/asm/device.h b/arch/arm/include/asm/device.h index 9f390ce..942913e 100644 --- a/arch/arm/include/asm/device.h +++ b/arch/arm/include/asm/device.h @@ -10,6 +10,9 @@ struct dev_archdata { #ifdef CONFIG_DMABOUNCE struct dmabounce_device_info *dmabounce; #endif +#ifdef CONFIG_CMA + struct cma *cma_area; +#endif }; struct pdev_archdata { diff --git a/arch/arm/include/asm/dma-contiguous.h b/arch/arm/include/asm/dma-contiguous.h new file mode 100644 index 0000000..6be12ba --- /dev/null +++ b/arch/arm/include/asm/dma-contiguous.h @@ -0,0 +1,33 @@ +#ifndef ASMARM_DMA_CONTIGUOUS_H +#define ASMARM_DMA_CONTIGUOUS_H + +#ifdef __KERNEL__ + +#include <linux/device.h> +#include <linux/dma-contiguous.h> + +#ifdef CONFIG_CMA + +#define MAX_CMA_AREAS (8) + +void dma_contiguous_early_fixup(phys_addr_t base, unsigned long size); + +static inline struct cma *get_dev_cma_area(struct device *dev) +{ + if (dev && dev->archdata.cma_area) + return dev->archdata.cma_area; + return dma_contiguous_default_area; +} + +static inline void set_dev_cma_area(struct device *dev, struct cma *cma) +{ + dev->archdata.cma_area = cma; +} + +#else + +#define MAX_CMA_AREAS (0) + +#endif +#endif +#endif diff --git a/arch/arm/include/asm/mach/map.h b/arch/arm/include/asm/mach/map.h index d2fedb5..05343de 100644 --- a/arch/arm/include/asm/mach/map.h +++ b/arch/arm/include/asm/mach/map.h @@ -29,6 +29,7 @@ struct map_desc { #define MT_MEMORY_NONCACHED 11 #define MT_MEMORY_DTCM 12 #define MT_MEMORY_ITCM 13 +#define MT_MEMORY_DMA_READY 14 #ifdef CONFIG_MMU extern void iotable_init(struct map_desc *, int); diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index 0a0a1e7..a0006c9 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -17,13 +17,17 @@ #include <linux/init.h> #include <linux/device.h> #include <linux/dma-mapping.h> +#include <linux/dma-contiguous.h> #include <linux/highmem.h> +#include <linux/memblock.h> #include <asm/memory.h> #include <asm/highmem.h> #include <asm/cacheflush.h> #include <asm/tlbflush.h> #include <asm/sizes.h> +#include <asm/mach/map.h> +#include <asm/dma-contiguous.h> #include "mm.h" @@ -54,6 +58,19 @@ static u64 get_coherent_dma_mask(struct device *dev) return mask; } +static void __dma_clear_buffer(struct page *page, size_t size) +{ + void *ptr; + /* + * Ensure that the allocated pages are zeroed, and that any data + * lurking in the kernel direct-mapped region is invalidated. + */ + ptr = page_address(page); + memset(ptr, 0, size); + dmac_flush_range(ptr, ptr + size); + outer_flush_range(__pa(ptr), __pa(ptr) + size); +} + /* * Allocate a DMA buffer for 'dev' of size 'size' using the * specified gfp mask. Note that 'size' must be page aligned. @@ -62,23 +79,6 @@ static struct page *__dma_alloc_buffer(struct device *dev, size_t size, gfp_t gf { unsigned long order = get_order(size); struct page *page, *p, *e; - void *ptr; - u64 mask = get_coherent_dma_mask(dev); - -#ifdef CONFIG_DMA_API_DEBUG - u64 limit = (mask + 1) & ~mask; - if (limit && size >= limit) { - dev_warn(dev, "coherent allocation too big (requested %#x mask %#llx)\n", - size, mask); - return NULL; - } -#endif - - if (!mask) - return NULL; - - if (mask < 0xffffffffULL) - gfp |= GFP_DMA; page = alloc_pages(gfp, order); if (!page) @@ -91,14 +91,7 @@ static struct page *__dma_alloc_buffer(struct device *dev, size_t size, gfp_t gf for (p = page + (size >> PAGE_SHIFT), e = page + (1 << order); p < e; p++) __free_page(p); - /* - * Ensure that the allocated pages are zeroed, and that any data - * lurking in the kernel direct-mapped region is invalidated. - */ - ptr = page_address(page); - memset(ptr, 0, size); - dmac_flush_range(ptr, ptr + size); - outer_flush_range(__pa(ptr), __pa(ptr) + size); + __dma_clear_buffer(page, size); return page; } @@ -157,6 +150,9 @@ static int __init consistent_init(void) int i = 0; u32 base = CONSISTENT_BASE; + if (cpu_architecture() >= CPU_ARCH_ARMv6) + return 0; + do { pgd = pgd_offset(&init_mm, base); @@ -188,9 +184,102 @@ static int __init consistent_init(void) return ret; } - core_initcall(consistent_init); +static void *__alloc_from_contiguous(struct device *dev, size_t size, + pgprot_t prot, struct page **ret_page); + +static struct arm_vmregion_head coherent_head = { + .vm_lock = __SPIN_LOCK_UNLOCKED(&coherent_head.vm_lock), + .vm_list = LIST_HEAD_INIT(coherent_head.vm_list), +}; + +size_t coherent_pool_size = CONSISTENT_DMA_SIZE / 8; + +static int __init early_coherent_pool(char *p) +{ + coherent_pool_size = memparse(p, &p); + return 0; +} +early_param("coherent_pool", early_coherent_pool); + +/* + * Initialise the coherent pool for atomic allocations. + */ +static int __init coherent_init(void) +{ + pgprot_t prot = pgprot_dmacoherent(pgprot_kernel); + size_t size = coherent_pool_size; + struct page *page; + void *ptr; + + if (cpu_architecture() < CPU_ARCH_ARMv6) + return 0; + + ptr = __alloc_from_contiguous(NULL, size, prot, &page); + if (ptr) { + coherent_head.vm_start = (unsigned long) ptr; + coherent_head.vm_end = (unsigned long) ptr + size; + printk(KERN_INFO "DMA: preallocated %u KiB pool for atomic coherent allocations\n", + (unsigned)size / 1024); + return 0; + } + printk(KERN_ERR "DMA: failed to allocate %u KiB pool for atomic coherent allocation\n", + (unsigned)size / 1024); + return -ENOMEM; +} +/* + * CMA is activated by core_initcall, so we must be called after it + */ +postcore_initcall(coherent_init); + +struct dma_contiguous_early_reserve { + phys_addr_t base; + unsigned long size; +}; + +static struct dma_contiguous_early_reserve +dma_mmu_remap[MAX_CMA_AREAS] __initdata; + +static int dma_mmu_remap_num __initdata; + +void __init dma_contiguous_early_fixup(phys_addr_t base, unsigned long size) +{ + dma_mmu_remap[dma_mmu_remap_num].base = base; + dma_mmu_remap[dma_mmu_remap_num].size = size; + dma_mmu_remap_num++; +} + +void __init dma_contiguous_remap(void) +{ + int i; + for (i = 0; i < dma_mmu_remap_num; i++) { + phys_addr_t start = dma_mmu_remap[i].base; + phys_addr_t end = start + dma_mmu_remap[i].size; + struct map_desc map; + unsigned long addr; + + if (end > arm_lowmem_limit) + end = arm_lowmem_limit; + if (start >= end) + return; + + map.pfn = __phys_to_pfn(start); + map.virtual = __phys_to_virt(start); + map.length = end - start; + map.type = MT_MEMORY_DMA_READY; + + /* + * Clear previous low-memory mapping + */ + for (addr = __phys_to_virt(start); addr < __phys_to_virt(end); + addr += PGDIR_SIZE) + pmd_clear(pmd_off_k(addr)); + + iotable_init(&map, 1); + } +} + static void * __dma_alloc_remap(struct page *page, size_t size, gfp_t gfp, pgprot_t prot) { @@ -296,31 +385,178 @@ static void __dma_free_remap(void *cpu_addr, size_t size) arm_vmregion_free(&consistent_head, c); } +static int __dma_update_pte(pte_t *pte, pgtable_t token, unsigned long addr, + void *data) +{ + struct page *page = virt_to_page(addr); + pgprot_t prot = *(pgprot_t *)data; + + set_pte_ext(pte, mk_pte(page, prot), 0); + return 0; +} + +static void __dma_remap(struct page *page, size_t size, pgprot_t prot) +{ + unsigned long start = (unsigned long) page_address(page); + unsigned end = start + size; + + apply_to_page_range(&init_mm, start, size, __dma_update_pte, &prot); + dsb(); + flush_tlb_kernel_range(start, end); +} + +static void *__alloc_remap_buffer(struct device *dev, size_t size, gfp_t gfp, + pgprot_t prot, struct page **ret_page) +{ + struct page *page; + void *ptr; + page = __dma_alloc_buffer(dev, size, gfp); + if (!page) + return NULL; + + ptr = __dma_alloc_remap(page, size, gfp, prot); + if (!ptr) { + __dma_free_buffer(page, size); + return NULL; + } + + *ret_page = page; + return ptr; +} + +static void *__alloc_from_pool(struct device *dev, size_t size, + struct page **ret_page) +{ + struct arm_vmregion *c; + size_t align; + + if (!coherent_head.vm_start) { + printk(KERN_ERR "%s: coherent pool not initialised!\n", + __func__); + dump_stack(); + return NULL; + } + + align = 1 << fls(size - 1); + c = arm_vmregion_alloc(&coherent_head, align, size, 0); + if (c) { + void *ptr = (void *)c->vm_start; + struct page *page = virt_to_page(ptr); + *ret_page = page; + return ptr; + } + return NULL; +} + +static int __free_from_pool(void *cpu_addr, size_t size) +{ + unsigned long start = (unsigned long)cpu_addr; + unsigned long end = start + size; + struct arm_vmregion *c; + + if (start < coherent_head.vm_start || end > coherent_head.vm_end) + return 0; + + c = arm_vmregion_find_remove(&coherent_head, (unsigned long)start); + + if ((c->vm_end - c->vm_start) != size) { + printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n", + __func__, c->vm_end - c->vm_start, size); + dump_stack(); + size = c->vm_end - c->vm_start; + } + + arm_vmregion_free(&coherent_head, c); + return 1; +} + +static void *__alloc_from_contiguous(struct device *dev, size_t size, + pgprot_t prot, struct page **ret_page) +{ + unsigned long order = get_order(size); + size_t count = size >> PAGE_SHIFT; + struct page *page; + + page = dma_alloc_from_contiguous(dev, count, order); + if (!page) + return NULL; + + __dma_clear_buffer(page, size); + __dma_remap(page, size, prot); + + *ret_page = page; + return page_address(page); +} + +static void __free_from_contiguous(struct device *dev, struct page *page, + size_t size) +{ + __dma_remap(page, size, pgprot_kernel); + dma_release_from_contiguous(dev, page, size >> PAGE_SHIFT); +} + +#define nommu() 0 + #else /* !CONFIG_MMU */ -#define __dma_alloc_remap(page, size, gfp, prot) page_address(page) -#define __dma_free_remap(addr, size) do { } while (0) +#define nommu() 1 + +#define __alloc_remap_buffer(dev, size, gfp, prot, ret) NULL +#define __alloc_from_pool(dev, size, ret_page) NULL +#define __alloc_from_contiguous(dev, size, prot, ret) NULL +#define __free_from_pool(cpu_addr, size) 0 +#define __free_from_contiguous(dev, page, size) do { } while (0) +#define __dma_free_remap(cpu_addr, size) do { } while (0) #endif /* CONFIG_MMU */ -static void * -__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp, - pgprot_t prot) +static void *__alloc_simple_buffer(struct device *dev, size_t size, gfp_t gfp, + struct page **ret_page) { struct page *page; + page = __dma_alloc_buffer(dev, size, gfp); + if (!page) + return NULL; + + *ret_page = page; + return page_address(page); +} + + + +static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, + gfp_t gfp, pgprot_t prot) +{ + u64 mask = get_coherent_dma_mask(dev); + struct page *page = NULL; void *addr; - *handle = ~0; - size = PAGE_ALIGN(size); +#ifdef CONFIG_DMA_API_DEBUG + u64 limit = (mask + 1) & ~mask; + if (limit && size >= limit) { + dev_warn(dev, "coherent allocation too big (requested %#x mask %#llx)\n", + size, mask); + return NULL; + } +#endif - page = __dma_alloc_buffer(dev, size, gfp); - if (!page) + if (!mask) return NULL; - if (!arch_is_coherent()) - addr = __dma_alloc_remap(page, size, gfp, prot); + if (mask < 0xffffffffULL) + gfp |= GFP_DMA; + + *handle = ~0; + size = PAGE_ALIGN(size); + + if (arch_is_coherent() || nommu()) + addr = __alloc_simple_buffer(dev, size, gfp, &page); + else if (cpu_architecture() < CPU_ARCH_ARMv6) + addr = __alloc_remap_buffer(dev, size, gfp, prot, &page); + else if (gfp & GFP_ATOMIC) + addr = __alloc_from_pool(dev, size, &page); else - addr = page_address(page); + addr = __alloc_from_contiguous(dev, size, prot, &page); if (addr) *handle = pfn_to_dma(dev, page_to_pfn(page)); @@ -332,8 +568,8 @@ __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp, * Allocate DMA-coherent memory space and return both the kernel remapped * virtual and bus address for that space. */ -void * -dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp) +void *dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, + gfp_t gfp) { void *memory; @@ -362,25 +598,11 @@ static int dma_mmap(struct device *dev, struct vm_area_struct *vma, { int ret = -ENXIO; #ifdef CONFIG_MMU - unsigned long user_size, kern_size; - struct arm_vmregion *c; - - user_size = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; - - c = arm_vmregion_find(&consistent_head, (unsigned long)cpu_addr); - if (c) { - unsigned long off = vma->vm_pgoff; - - kern_size = (c->vm_end - c->vm_start) >> PAGE_SHIFT; - - if (off < kern_size && - user_size <= (kern_size - off)) { - ret = remap_pfn_range(vma, vma->vm_start, - page_to_pfn(c->vm_pages) + off, - user_size << PAGE_SHIFT, - vma->vm_page_prot); - } - } + unsigned long pfn = dma_to_pfn(dev, dma_addr); + ret = remap_pfn_range(vma, vma->vm_start, + pfn + vma->vm_pgoff, + vma->vm_end - vma->vm_start, + vma->vm_page_prot); #endif /* CONFIG_MMU */ return ret; @@ -402,23 +624,33 @@ int dma_mmap_writecombine(struct device *dev, struct vm_area_struct *vma, } EXPORT_SYMBOL(dma_mmap_writecombine); + /* - * free a page as defined by the above mapping. - * Must not be called with IRQs disabled. + * Free a buffer as defined by the above mapping. */ void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr_t handle) { - WARN_ON(irqs_disabled()); + struct page *page = pfn_to_page(dma_to_pfn(dev, handle)); if (dma_release_from_coherent(dev, get_order(size), cpu_addr)) return; size = PAGE_ALIGN(size); - if (!arch_is_coherent()) + if (arch_is_coherent() || nommu()) { + __dma_free_buffer(page, size); + } else if (cpu_architecture() < CPU_ARCH_ARMv6) { __dma_free_remap(cpu_addr, size); - - __dma_free_buffer(pfn_to_page(dma_to_pfn(dev, handle)), size); + __dma_free_buffer(page, size); + } else { + if (__free_from_pool(cpu_addr, size)) + return; + /* + * Non-atomic allocations cannot be freed with IRQs disabled + */ + WARN_ON(irqs_disabled()); + __free_from_contiguous(dev, page, size); + } } EXPORT_SYMBOL(dma_free_coherent); diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c index 91bca35..b35b782 100644 --- a/arch/arm/mm/init.c +++ b/arch/arm/mm/init.c @@ -20,6 +20,7 @@ #include <linux/gfp.h> #include <linux/memblock.h> #include <linux/sort.h> +#include <linux/dma-contiguous.h> #include <asm/mach-types.h> #include <asm/prom.h> @@ -370,6 +371,13 @@ void __init arm_memblock_init(struct meminfo *mi, struct machine_desc *mdesc) if (mdesc->reserve) mdesc->reserve(); + /* reserve memory for DMA contigouos allocations */ +#ifdef CONFIG_ZONE_DMA + dma_contiguous_reserve(PHYS_OFFSET + mdesc->dma_zone_size - 1); +#else + dma_contiguous_reserve(0); +#endif + memblock_analyze(); memblock_dump_all(); } diff --git a/arch/arm/mm/mm.h b/arch/arm/mm/mm.h index 0105667..4bc58df 100644 --- a/arch/arm/mm/mm.h +++ b/arch/arm/mm/mm.h @@ -29,5 +29,8 @@ extern u32 arm_dma_limit; #define arm_dma_limit ((u32)~0) #endif +extern phys_addr_t arm_lowmem_limit; + void __init bootmem_init(void); void arm_mm_memblock_reserve(void); +void dma_contiguous_remap(void); diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c index 594d677..bc4e7e8 100644 --- a/arch/arm/mm/mmu.c +++ b/arch/arm/mm/mmu.c @@ -273,6 +273,11 @@ static struct mem_type mem_types[] = { .prot_l1 = PMD_TYPE_TABLE, .domain = DOMAIN_KERNEL, }, + [MT_MEMORY_DMA_READY] = { + .prot_pte = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY, + .prot_l1 = PMD_TYPE_TABLE, + .domain = DOMAIN_KERNEL, + }, }; const struct mem_type *get_mem_type(unsigned int type) @@ -414,6 +419,7 @@ static void __init build_mem_type_table(void) if (arch_is_coherent() && cpu_is_xsc3()) { mem_types[MT_MEMORY].prot_sect |= PMD_SECT_S; mem_types[MT_MEMORY].prot_pte |= L_PTE_SHARED; + mem_types[MT_MEMORY_DMA_READY].prot_pte |= L_PTE_SHARED; mem_types[MT_MEMORY_NONCACHED].prot_sect |= PMD_SECT_S; mem_types[MT_MEMORY_NONCACHED].prot_pte |= L_PTE_SHARED; } @@ -443,6 +449,7 @@ static void __init build_mem_type_table(void) mem_types[MT_DEVICE_CACHED].prot_pte |= L_PTE_SHARED; mem_types[MT_MEMORY].prot_sect |= PMD_SECT_S; mem_types[MT_MEMORY].prot_pte |= L_PTE_SHARED; + mem_types[MT_MEMORY_DMA_READY].prot_pte |= L_PTE_SHARED; mem_types[MT_MEMORY_NONCACHED].prot_sect |= PMD_SECT_S; mem_types[MT_MEMORY_NONCACHED].prot_pte |= L_PTE_SHARED; } @@ -482,6 +489,7 @@ static void __init build_mem_type_table(void) mem_types[MT_HIGH_VECTORS].prot_l1 |= ecc_mask; mem_types[MT_MEMORY].prot_sect |= ecc_mask | cp->pmd; mem_types[MT_MEMORY].prot_pte |= kern_pgprot; + mem_types[MT_MEMORY_DMA_READY].prot_pte |= kern_pgprot; mem_types[MT_MEMORY_NONCACHED].prot_sect |= ecc_mask; mem_types[MT_ROM].prot_sect |= cp->pmd; @@ -561,7 +569,7 @@ static void __init alloc_init_section(pud_t *pud, unsigned long addr, * L1 entries, whereas PGDs refer to a group of L1 entries making * up one logical pointer to an L2 table. */ - if (((addr | end | phys) & ~SECTION_MASK) == 0) { + if (type->prot_sect && ((addr | end | phys) & ~SECTION_MASK) == 0) { pmd_t *p = pmd; if (addr & SECTION_SIZE) @@ -757,7 +765,7 @@ static int __init early_vmalloc(char *arg) } early_param("vmalloc", early_vmalloc); -static phys_addr_t lowmem_limit __initdata = 0; +phys_addr_t arm_lowmem_limit __initdata = 0; void __init sanity_check_meminfo(void) { @@ -826,8 +834,8 @@ void __init sanity_check_meminfo(void) bank->size = newsize; } #endif - if (!bank->highmem && bank->start + bank->size > lowmem_limit) - lowmem_limit = bank->start + bank->size; + if (!bank->highmem && bank->start + bank->size > arm_lowmem_limit) + arm_lowmem_limit = bank->start + bank->size; j++; } @@ -852,7 +860,7 @@ void __init sanity_check_meminfo(void) } #endif meminfo.nr_banks = j; - memblock_set_current_limit(lowmem_limit); + memblock_set_current_limit(arm_lowmem_limit); } static inline void prepare_page_table(void) @@ -877,8 +885,8 @@ static inline void prepare_page_table(void) * Find the end of the first block of lowmem. */ end = memblock.memory.regions[0].base + memblock.memory.regions[0].size; - if (end >= lowmem_limit) - end = lowmem_limit; + if (end >= arm_lowmem_limit) + end = arm_lowmem_limit; /* * Clear out all the kernel space mappings, except for the first @@ -1010,8 +1018,8 @@ static void __init map_lowmem(void) phys_addr_t end = start + reg->size; struct map_desc map; - if (end > lowmem_limit) - end = lowmem_limit; + if (end > arm_lowmem_limit) + end = arm_lowmem_limit; if (start >= end) break; @@ -1032,11 +1040,12 @@ void __init paging_init(struct machine_desc *mdesc) { void *zero_page; - memblock_set_current_limit(lowmem_limit); + memblock_set_current_limit(arm_lowmem_limit); build_mem_type_table(); prepare_page_table(); map_lowmem(); + dma_contiguous_remap(); devicemaps_init(mdesc); kmap_init(); -- 1.7.1.569.g6f426 ^ permalink raw reply related [flat|nested] 46+ messages in thread
[parent not found: <CAMjpGUch=ogFQwBLqOukKVnyh60600jw5tMq-KYeNGSZ2PLQpA@mail.gmail.com>]
* RE: [PATCH 7/8] ARM: integrate CMA with DMA-mapping subsystem [not found] ` <CAMjpGUch=ogFQwBLqOukKVnyh60600jw5tMq-KYeNGSZ2PLQpA@mail.gmail.com> @ 2011-09-21 13:47 ` Marek Szyprowski 0 siblings, 0 replies; 46+ messages in thread From: Marek Szyprowski @ 2011-09-21 13:47 UTC (permalink / raw) To: 'Mike Frysinger' Cc: linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig, 'Michal Nazarewicz', 'Kyungmin Park', 'Russell King', 'Andrew Morton', 'KAMEZAWA Hiroyuki', 'Ankita Garg', 'Daniel Walker', 'Mel Gorman', 'Arnd Bergmann', 'Jesse Barker', 'Jonathan Corbet', 'Shariq Hasnain', 'Chunsang Jeong' Hello, On Thursday, September 08, 2011 7:27 PM Mike Frysinger wrote: > On Fri, Aug 19, 2011 at 10:27, Marek Szyprowski wrote: > > arch/arm/include/asm/device.h | 3 + > > arch/arm/include/asm/dma-contiguous.h | 33 +++ > > seems like these would be good asm-generic/ additions rather than arm Only some of them can be really moved to asm-generic imho. The following lines are definitely architecture specific: void dma_contiguous_early_fixup(phys_addr_t base, unsigned long size); Some other archs might define empty fixup function. Right now only ARM architecture is the real client of the CMA. IMHO if any other arch stats using CMA, some of the CMA definitions can be then moved to asm-generic. Right now I wanted to keep it as simple as possible. Best regards -- Marek Szyprowski Samsung Poland R&D Center ^ permalink raw reply [flat|nested] 46+ messages in thread
* [PATCH 8/8] ARM: S5PV210: example of CMA private area for FIMC device on Goni board 2011-08-19 14:27 [PATCHv15 0/8] Contiguous Memory Allocator Marek Szyprowski ` (6 preceding siblings ...) 2011-08-19 14:27 ` [PATCH 7/8] ARM: integrate CMA with DMA-mapping subsystem Marek Szyprowski @ 2011-08-19 14:27 ` Marek Szyprowski 7 siblings, 0 replies; 46+ messages in thread From: Marek Szyprowski @ 2011-08-19 14:27 UTC (permalink / raw) To: linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig Cc: Michal Nazarewicz, Marek Szyprowski, Kyungmin Park, Russell King, Andrew Morton, KAMEZAWA Hiroyuki, Ankita Garg, Daniel Walker, Mel Gorman, Arnd Bergmann, Jesse Barker, Jonathan Corbet, Shariq Hasnain, Chunsang Jeong This patch is an example how device private CMA area can be activated. It creates one CMA region and assigns it to the first s5p-fimc device on Samsung Goni S5PC110 board. Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> --- arch/arm/mach-s5pv210/mach-goni.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diff --git a/arch/arm/mach-s5pv210/mach-goni.c b/arch/arm/mach-s5pv210/mach-goni.c index 14578f5..f766c45 100644 --- a/arch/arm/mach-s5pv210/mach-goni.c +++ b/arch/arm/mach-s5pv210/mach-goni.c @@ -26,6 +26,7 @@ #include <linux/input.h> #include <linux/gpio.h> #include <linux/interrupt.h> +#include <linux/dma-contiguous.h> #include <asm/mach/arch.h> #include <asm/mach/map.h> @@ -857,6 +858,9 @@ static void __init goni_map_io(void) static void __init goni_reserve(void) { s5p_mfc_reserve_mem(0x43000000, 8 << 20, 0x51000000, 8 << 20); + + /* Create private 16MiB contiguous memory area for s5p-fimc.0 device */ + dma_declare_contiguous(&s5p_device_fimc0.dev, 16*SZ_1M, 0); } static void __init goni_machine_init(void) -- 1.7.1.569.g6f426 ^ permalink raw reply related [flat|nested] 46+ messages in thread
* [PATCHv12 0/8] Contiguous Memory Allocator @ 2011-07-20 8:57 Marek Szyprowski 2011-07-20 8:57 ` [PATCH 6/8] drivers: add " Marek Szyprowski 0 siblings, 1 reply; 46+ messages in thread From: Marek Szyprowski @ 2011-07-20 8:57 UTC (permalink / raw) To: linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig Cc: Michal Nazarewicz, Marek Szyprowski, Kyungmin Park, Andrew Morton, KAMEZAWA Hiroyuki, Ankita Garg, Daniel Walker, Mel Gorman, Arnd Bergmann, Jesse Barker, Jonathan Corbet, Chunsang Jeong, Russell King Hello everyone, This is yet another round of Contiguous Memory Allocator patches. Now I focused mainly on the integration of CMA to DMA mapping subsystem on ARM architecture. In this version I've tried to solve the issue of the aliasing in coherent memory mapping that was present in earlier versions of DMA mapping framework. The proposed solution should be considered as a proof-of-concept. Right now it doesn't support GFP_ATOMIC allocations. Support for them is on my TODO list and will be implemented on top of the "ARM: DMA: steal memory for DMA coherent mappings" patch by Russell King. A few words for these who see CMA for the first time: The Contiguous Memory Allocator (CMA) makes it possible for device drivers to allocate big contiguous chunks of memory after the system has booted. The main difference from the similar frameworks is the fact that CMA allows to transparently reuse memory region reserved for the big chunk allocation as a system memory, so no memory is wasted when no big chunk is allocated. Once the alloc request is issued, the framework will migrate system pages to create a required big chunk of physically contiguous memory. For more information you can refer to nice LWN articles: http://lwn.net/Articles/447405/ and http://lwn.net/Articles/450286/ as well as links to previous versions of the CMA framework. The CMA framework has been initially developed by Michal Nazarewicz at Samsung Poland R&D Center. Since version 9, I've taken over the development, because Michal has left the company. The current version of CMA is a set of helper functions for DMA mapping framework that handles allocation of contiguous memory blocks. The difference between this patchset and Kamezawa's alloc_contig_pages() are: 1. alloc_contig_pages() requires MAX_ORDER alignment of allocations which may be unsuitable for embeded systems where a few MiBs are required. Lack of the requirement on the alignment means that several threads might try to access the same pageblock/page. To prevent this from happening CMA uses a mutex so that only one allocating/releasing function may run at one point. 2. CMA may use its own migratetype (MIGRATE_CMA) which behaves similarly to ZONE_MOVABLE but can be put in arbitrary places. This is required for us since we need to define two disjoint memory ranges inside system RAM. (ie. in two memory banks (do not confuse with nodes)). 3. alloc_contig_pages() scans memory in search for range that could be migrated. CMA on the other hand maintains its own allocator to decide where to allocate memory for device drivers and then tries to migrate pages from that part if needed. This is not strictly required but I somehow feel it might be faster. The integration with ARM DMA-mapping subsystem is done on 2 levels. During early boot memory reserved for contiguous areas are remapped with 2-level page tables. This enables us to change cache attributes of the individual pages from such area on request. Then, DMA mapping subsystem is updated to use dma_alloc_from_contiguous() call instead of alloc_pages() and perform page attributes remapping. Current version have been tested on Samsung S5PC110 based Goni machine and s5p-fimc V4L2 driver. The driver itself uses videobuf2 dma-contig memory allocator, which in turn relies on dma_alloc_coherent() from DMA-mapping subsystem. By integrating CMA with DMA-mapping we managed to get this driver working with CMA without any single change required in the driver or videobuf2-dma-contig allocator. TODO: - implement GPF_ATOMIC allocations - implement support for contiguous memory areas placed in HIGHMEM zone Best regards -- Marek Szyprowski Samsung Poland R&D Center Links to previous versions of the patchset: v11: <http://www.spinics.net/lists/linux-mm/msg21868.html> v10: <http://www.spinics.net/lists/linux-mm/msg20761.html> v9: <http://article.gmane.org/gmane.linux.kernel.mm/60787> v8: <http://article.gmane.org/gmane.linux.kernel.mm/56855> v7: <http://article.gmane.org/gmane.linux.kernel.mm/55626> v6: <http://article.gmane.org/gmane.linux.kernel.mm/55626> v5: (intentionally left out as CMA v5 was identical to CMA v4) v4: <http://article.gmane.org/gmane.linux.kernel.mm/52010> v3: <http://article.gmane.org/gmane.linux.kernel.mm/51573> v2: <http://article.gmane.org/gmane.linux.kernel.mm/50986> v1: <http://article.gmane.org/gmane.linux.kernel.mm/50669> Changelog: v12: 1. Fixed 2 nasty bugs in dma-contiguous allocator: - alignment argument was not passed correctly - range for dma_release_from_contiguous was not checked correctly 2. Added support for architecture specfic dma_contiguous_early_fixup() function 3. CMA and DMA-mapping integration for ARM architechture has been rewritten to take care of the memory aliasing issue that might happen for newer ARM CPUs (mapping of the same pages with different cache attributes is forbidden). TODO: add support for GFP_ATOMIC allocations basing on the "ARM: DMA: steal memory for DMA coherent mappings" patch and implement support for contiguous memory areas that are placed in HIGHMEM zone v11: 1. Removed genalloc usage and replaced it with direct calls to bitmap_* functions, dropped patches that are not needed anymore (genalloc extensions) 2. Moved all contiguous area management code from mm/cma.c to drivers/base/dma-contiguous.c 3. Renamed cm_alloc/free to dma_alloc/release_from_contiguous 4. Introduced global, system wide (default) contiguous area configured with kernel config and kernel cmdline parameters 5. Simplified initialization to just one function: dma_declare_contiguous() 6. Added example of device private memory contiguous area v10: 1. Rebased onto 3.0-rc2 and resolved all conflicts 2. Simplified CMA to be just a pure memory allocator, for use with platfrom/bus specific subsystems, like dma-mapping. Removed all device specific functions are calls. 3. Integrated with ARM DMA-mapping subsystem. 4. Code cleanup here and there. 5. Removed private context support. v9: 1. Rebased onto 2.6.39-rc1 and resolved all conflicts 2. Fixed a bunch of nasty bugs that happened when the allocation failed (mainly kernel oops due to NULL ptr dereference). 3. Introduced testing code: cma-regions compatibility layer and videobuf2-cma memory allocator module. v8: 1. The alloc_contig_range() function has now been separated from CMA and put in page_allocator.c. This function tries to migrate all LRU pages in specified range and then allocate the range using alloc_contig_freed_pages(). 2. Support for MIGRATE_CMA has been separated from the CMA code. I have not tested if CMA works with ZONE_MOVABLE but I see no reasons why it shouldn't. 3. I have added a @private argument when creating CMA contexts so that one can reserve memory and not share it with the rest of the system. This way, CMA acts only as allocation algorithm. v7: 1. A lot of functionality that handled driver->allocator_context mapping has been removed from the patchset. This is not to say that this code is not needed, it's just not worth posting everything in one patchset. Currently, CMA is "just" an allocator. It uses it's own migratetype (MIGRATE_CMA) for defining ranges of pageblokcs which behave just like ZONE_MOVABLE but dispite the latter can be put in arbitrary places. 2. The migration code that was introduced in the previous version actually started working. v6: 1. Most importantly, v6 introduces support for memory migration. The implementation is not yet complete though. Migration support means that when CMA is not using memory reserved for it, page allocator can allocate pages from it. When CMA wants to use the memory, the pages have to be moved and/or evicted as to make room for CMA. To make it possible it must be guaranteed that only movable and reclaimable pages are allocated in CMA controlled regions. This is done by introducing a MIGRATE_CMA migrate type that guarantees exactly that. Some of the migration code is "borrowed" from Kamezawa Hiroyuki's alloc_contig_pages() implementation. The main difference is that thanks to MIGRATE_CMA migrate type CMA assumes that memory controlled by CMA are is always movable or reclaimable so that it makes allocation decisions regardless of the whether some pages are actually allocated and migrates them if needed. The most interesting patches from the patchset that implement the functionality are: 09/13: mm: alloc_contig_free_pages() added 10/13: mm: MIGRATE_CMA migration type added 11/13: mm: MIGRATE_CMA isolation functions added 12/13: mm: cma: Migration support added [wip] Currently, kernel panics in some situations which I am trying to investigate. 2. cma_pin() and cma_unpin() functions has been added (after a conversation with Johan Mossberg). The idea is that whenever hardware does not use the memory (no transaction is on) the chunk can be moved around. This would allow defragmentation to be implemented if desired. No defragmentation algorithm is provided at this time. 3. Sysfs support has been replaced with debugfs. I always felt unsure about the sysfs interface and when Greg KH pointed it out I finally got to rewrite it to debugfs. v5: (intentionally left out as CMA v5 was identical to CMA v4) v4: 1. The "asterisk" flag has been removed in favour of requiring that platform will provide a "*=<regions>" rule in the map attribute. 2. The terminology has been changed slightly renaming "kind" to "type" of memory. In the previous revisions, the documentation indicated that device drivers define memory kinds and now, v3: 1. The command line parameters have been removed (and moved to a separate patch, the fourth one). As a consequence, the cma_set_defaults() function has been changed -- it no longer accepts a string with list of regions but an array of regions. 2. The "asterisk" attribute has been removed. Now, each region has an "asterisk" flag which lets one specify whether this region should by considered "asterisk" region. 3. SysFS support has been moved to a separate patch (the third one in the series) and now also includes list of regions. v2: 1. The "cma_map" command line have been removed. In exchange, a SysFS entry has been created under kernel/mm/contiguous. The intended way of specifying the attributes is a cma_set_defaults() function called by platform initialisation code. "regions" attribute (the string specified by "cma" command line parameter) can be overwritten with command line parameter; the other attributes can be changed during run-time using the SysFS entries. 2. The behaviour of the "map" attribute has been modified slightly. Currently, if no rule matches given device it is assigned regions specified by the "asterisk" attribute. It is by default built from the region names given in "regions" attribute. 3. Devices can register private regions as well as regions that can be shared but are not reserved using standard CMA mechanisms. A private region has no name and can be accessed only by devices that have the pointer to it. 4. The way allocators are registered has changed. Currently, a cma_allocator_register() function is used for that purpose. Moreover, allocators are attached to regions the first time memory is registered from the region or when allocator is registered which means that allocators can be dynamic modules that are loaded after the kernel booted (of course, it won't be possible to allocate a chunk of memory from a region if allocator is not loaded). 5. Index of new functions: +static inline dma_addr_t __must_check +cma_alloc_from(const char *regions, size_t size, + dma_addr_t alignment) +static inline int +cma_info_about(struct cma_info *info, const const char *regions) +int __must_check cma_region_register(struct cma_region *reg); +dma_addr_t __must_check +cma_alloc_from_region(struct cma_region *reg, + size_t size, dma_addr_t alignment); +static inline dma_addr_t __must_check +cma_alloc_from(const char *regions, + size_t size, dma_addr_t alignment); +int cma_allocator_register(struct cma_allocator *alloc); Patches in this patchset: mm: move some functions from memory_hotplug.c to page_isolation.c mm: alloc_contig_freed_pages() added Code "stolen" from Kamezawa. The first patch just moves code around and the second provide function for "allocates" already freed memory. mm: alloc_contig_range() added This is what Kamezawa asked: a function that tries to migrate all pages from given range and then use alloc_contig_freed_pages() (defined by the previous commit) to allocate those pages. mm: MIGRATE_CMA migration type added mm: MIGRATE_CMA isolation functions added Introduction of the new migratetype and support for it in CMA. MIGRATE_CMA works similar to ZONE_MOVABLE expect almost any memory range can be marked as one. mm: cma: Contiguous Memory Allocator added The code CMA code. Manages CMA contexts and performs memory allocations. ARM: integrate CMA with dma-mapping subsystem Main client of CMA frame work. CMA serves as a alloc_pages() replacement. ARM: S5PV210: example of CMA private area for FIMC device on Goni board Example of platform/board specific code that creates cma context and assigns it to particular device. Patch summary: KAMEZAWA Hiroyuki (2): mm: move some functions from memory_hotplug.c to page_isolation.c mm: alloc_contig_freed_pages() added Marek Szyprowski (3): drivers: add Contiguous Memory Allocator ARM: integrate CMA with dma-mapping subsystem ARM: S5PV210: example of CMA private area for FIMC device on Goni board Michal Nazarewicz (3): mm: alloc_contig_range() added mm: MIGRATE_CMA migration type added mm: MIGRATE_CMA isolation functions added arch/Kconfig | 3 + arch/arm/Kconfig | 1 + arch/arm/include/asm/device.h | 3 + arch/arm/include/asm/dma-contiguous.h | 33 +++ arch/arm/include/asm/mach/map.h | 1 + arch/arm/mach-s5pv210/Kconfig | 1 + arch/arm/mach-s5pv210/mach-goni.c | 8 + arch/arm/mm/dma-mapping.c | 244 +++----------------- arch/arm/mm/init.c | 3 + arch/arm/mm/mmu.c | 56 +++++- drivers/base/Kconfig | 77 +++++++ drivers/base/Makefile | 1 + drivers/base/dma-contiguous.c | 396 +++++++++++++++++++++++++++++++++ include/linux/dma-contiguous.h | 102 +++++++++ include/linux/mmzone.h | 41 +++- include/linux/page-isolation.h | 51 ++++- mm/Kconfig | 8 +- mm/compaction.c | 10 + mm/memory_hotplug.c | 111 --------- mm/page_alloc.c | 287 ++++++++++++++++++++++-- mm/page_isolation.c | 129 ++++++++++- 21 files changed, 1197 insertions(+), 369 deletions(-) create mode 100644 arch/arm/include/asm/dma-contiguous.h create mode 100644 drivers/base/dma-contiguous.c create mode 100644 include/linux/dma-contiguous.h -- 1.7.1.569.g6f426 ^ permalink raw reply [flat|nested] 46+ messages in thread
* [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-20 8:57 [PATCHv12 0/8] Contiguous Memory Allocator Marek Szyprowski @ 2011-07-20 8:57 ` Marek Szyprowski 0 siblings, 0 replies; 46+ messages in thread From: Marek Szyprowski @ 2011-07-20 8:57 UTC (permalink / raw) To: linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig Cc: Michal Nazarewicz, Marek Szyprowski, Kyungmin Park, Andrew Morton, KAMEZAWA Hiroyuki, Ankita Garg, Daniel Walker, Mel Gorman, Arnd Bergmann, Jesse Barker, Jonathan Corbet, Chunsang Jeong, Russell King The Contiguous Memory Allocator is a set of helper functions for DMA mapping framework that improves allocations of contiguous memory chunks. CMA grabs memory on system boot, marks it with CMA_MIGRATE_TYPE and gives back to the system. Kernel is allowed to allocate movable pages within CMA's managed memory so that it can be used for example for page cache when DMA mapping do not use it. On dma_alloc_from_contiguous() request such pages are migrated out of CMA area to free required contiguous block and fulfill the request. This allows to allocate large contiguous chunks of memory at any time assuming that there is enough free memory available in the system. This code is heavily based on earlier works by Michal Nazarewicz. Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> CC: Michal Nazarewicz <mina86@mina86.com> --- arch/Kconfig | 3 + drivers/base/Kconfig | 77 ++++++++ drivers/base/Makefile | 1 + drivers/base/dma-contiguous.c | 396 ++++++++++++++++++++++++++++++++++++++++ include/linux/dma-contiguous.h | 102 ++++++++++ 5 files changed, 579 insertions(+), 0 deletions(-) create mode 100644 drivers/base/dma-contiguous.c create mode 100644 include/linux/dma-contiguous.h diff --git a/arch/Kconfig b/arch/Kconfig index 26b0e23..228d761 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -124,6 +124,9 @@ config HAVE_ARCH_TRACEHOOK config HAVE_DMA_ATTRS bool +config HAVE_DMA_CONTIGUOUS + bool + config USE_GENERIC_SMP_HELPERS bool diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig index d57e8d0..c690d05 100644 --- a/drivers/base/Kconfig +++ b/drivers/base/Kconfig @@ -168,4 +168,81 @@ config SYS_HYPERVISOR bool default n +config CMA + bool "Contiguous Memory Allocator" + depends on HAVE_DMA_CONTIGUOUS && HAVE_MEMBLOCK + select MIGRATION + select CMA_MIGRATE_TYPE + help + This enables the Contiguous Memory Allocator which allows drivers + to allocate big physically-contiguous blocks of memory for use with + hardware components that do not support I/O map nor scatter-gather. + + For more information see <include/linux/dma-contiguous.h>. + If unsure, say "n". + +if CMA + +config CMA_DEBUG + bool "CMA debug messages (DEVELOPEMENT)" + help + Turns on debug messages in CMA. This produces KERN_DEBUG + messages for every CMA call as well as various messages while + processing calls such as dma_alloc_from_contiguous(). + This option does not affect warning and error messages. + +comment "Default contiguous memory area size:" + +config CMA_SIZE_ABSOLUTE + int "Absolute size (in MiB)" + default 16 + help + Defines the size (in MiB) of the default memory area for Contiguous + Memory Allocator. + +config CMA_SIZE_PERCENTAGE + int "Percentage of total memory" + default 10 + help + Defines the size of the default memory area for Contiguous Memory + Allocator as a percentage of the total memory in the system. + +choice + prompt "Selected region size" + default CMA_SIZE_SEL_ABSOLUTE + +config CMA_SIZE_SEL_ABSOLUTE + bool "Use absolute value only" + +config CMA_SIZE_SEL_PERCENTAGE + bool "Use percentage value only" + +config CMA_SIZE_SEL_MIN + bool "Use lower value (minimum)" + +config CMA_SIZE_SEL_MAX + bool "Use higher value (maximum)" + +endchoice + +config CMA_ALIGNMENT + int "Maximum PAGE_SIZE order of alignment for contiguous buffers" + range 4 9 + default 8 + help + DMA mapping framework by default aligns all buffers to the smallest + PAGE_SIZE order which is greater than or equal to the requested buffer + size. This works well for buffers up to a few hundreds kilobytes, but + for larger buffers it just a memory waste. With this parameter you can + specify the maximum PAGE_SIZE order for contiguous buffers. Larger + buffers will be aligned only to this specified order. The order is + expressed as a power of two multiplied by the PAGE_SIZE. + + For example, if your system defaults to 4KiB pages, the order value + of 8 means that the buffers will be aligned up to 1MiB only. + + If unsure, leave the default value "8". + +endif + endmenu diff --git a/drivers/base/Makefile b/drivers/base/Makefile index 4c5701c..be6aab4 100644 --- a/drivers/base/Makefile +++ b/drivers/base/Makefile @@ -5,6 +5,7 @@ obj-y := core.o sys.o bus.o dd.o syscore.o \ cpu.o firmware.o init.o map.o devres.o \ attribute_container.o transport_class.o obj-$(CONFIG_DEVTMPFS) += devtmpfs.o +obj-$(CONFIG_CMA) += dma-contiguous.o obj-y += power/ obj-$(CONFIG_HAS_DMA) += dma-mapping.o obj-$(CONFIG_HAVE_GENERIC_DMA_COHERENT) += dma-coherent.o diff --git a/drivers/base/dma-contiguous.c b/drivers/base/dma-contiguous.c new file mode 100644 index 0000000..7fdeaba --- /dev/null +++ b/drivers/base/dma-contiguous.c @@ -0,0 +1,396 @@ +/* + * Contiguous Memory Allocator for DMA mapping framework + * Copyright (c) 2010-2011 by Samsung Electronics. + * Written by: + * Marek Szyprowski <m.szyprowski@samsung.com> + * Michal Nazarewicz <mina86@mina86.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of the + * License or (at your optional) any later version of the license. + */ + +#define pr_fmt(fmt) "cma: " fmt + +#ifdef CONFIG_CMA_DEBUG +#ifndef DEBUG +# define DEBUG +#endif +#endif + +#include <asm/page.h> +#include <asm/dma-contiguous.h> + +#include <linux/memblock.h> +#include <linux/err.h> +#include <linux/mm.h> +#include <linux/mutex.h> +#include <linux/page-isolation.h> +#include <linux/slab.h> +#include <linux/swap.h> +#include <linux/mm_types.h> +#include <linux/dma-contiguous.h> + +#ifndef SZ_1M +#define SZ_1M (1 << 20) +#endif + +#ifdef phys_to_pfn +/* nothing to do */ +#elif defined __phys_to_pfn +# define phys_to_pfn __phys_to_pfn +#elif defined PFN_PHYS +# define phys_to_pfn PFN_PHYS +#else +# error correct phys_to_pfn implementation needed +#endif + +struct cma { + unsigned long base_pfn; + unsigned long count; + unsigned long *bitmap; +}; + +struct cma *dma_contiguous_default_area; + +static unsigned long size_abs = CONFIG_CMA_SIZE_ABSOLUTE * SZ_1M; +static unsigned long size_percent = CONFIG_CMA_SIZE_PERCENTAGE; +static long size_cmdline = -1; + +static int __init early_cma(char *p) +{ + pr_debug("%s(%s)\n", __func__, p); + size_cmdline = memparse(p, &p); + return 0; +} +early_param("cma", early_cma); + +static unsigned long __init __cma_early_get_total_pages(void) +{ + struct memblock_region *reg; + unsigned long total_pages = 0; + + /* + * We cannot use memblock_phys_mem_size() here, because + * memblock_analyze() has not been called yet. + */ + for_each_memblock(memory, reg) + total_pages += memblock_region_memory_end_pfn(reg) - + memblock_region_memory_base_pfn(reg); + return total_pages; +} + + +/** + * dma_contiguous_reserve() - reserve area for contiguous memory handling + * + * This funtion reserves memory from early allocator. It should be + * called by arch specific code once the early allocator (memblock or bootmem) + * has been activated and all other subsystems have already allocated/reserved + * memory. + */ +void __init dma_contiguous_reserve(void) +{ + unsigned long selected_size = 0; + unsigned long total_pages; + + pr_debug("%s()\n", __func__); + + total_pages = __cma_early_get_total_pages(); + size_percent *= (total_pages << PAGE_SHIFT) / 100; + + pr_debug("%s: available phys mem: %ld MiB\n", __func__, + (total_pages << PAGE_SHIFT) / SZ_1M); + +#ifdef CONFIG_CMA_SIZE_SEL_ABSOLUTE + selected_size = size_abs; +#endif +#ifdef CONFIG_CMA_SIZE_SEL_PERCENTAGE + selected_size = size_percent; +#endif +#ifdef CONFIG_CMA_SIZE_SEL_MIN + selected_size = min(size_abs, size_percent); +#endif +#ifdef CONFIG_CMA_SIZE_SEL_MAX + selected_size = max(size_abs, size_percent); +#endif + + if (size_cmdline != -1) + selected_size = size_cmdline; + + if (!selected_size) + return; + + pr_debug("%s: reserving %ld MiB for global area\n", __func__, + selected_size / SZ_1M); + + dma_declare_contiguous(NULL, selected_size, 0); +}; + +static DEFINE_MUTEX(cma_mutex); + +#ifdef CONFIG_DEBUG_VM + +static int __cma_activate_area(unsigned long base_pfn, unsigned long count) +{ + unsigned long pfn = base_pfn; + unsigned i = count; + struct zone *zone; + + pr_debug("%s(0x%08lx+0x%lx)\n", __func__, base_pfn, count); + + VM_BUG_ON(!pfn_valid(pfn)); + zone = page_zone(pfn_to_page(pfn)); + + do { + VM_BUG_ON(!pfn_valid(pfn)); + VM_BUG_ON(page_zone(pfn_to_page(pfn)) != zone); + if (!(pfn & (pageblock_nr_pages - 1))) + init_cma_reserved_pageblock(pfn_to_page(pfn)); + ++pfn; + } while (--i); + + return 0; +} + +#else + +static int __cma_activate_area(unsigned long base_pfn, unsigned long count) +{ + unsigned i = count >> pageblock_order; + struct page *p = pfn_to_page(base_pfn); + + pr_debug("%s(0x%08lx+0x%lx)\n", __func__, base_pfn, count); + + do { + init_cma_reserved_pageblock(p); + p += pageblock_nr_pages; + } while (--i); + + return 0; +} + +#endif + +static struct cma *__cma_create_area(unsigned long base_pfn, + unsigned long count) +{ + int bitmap_size = BITS_TO_LONGS(count) * sizeof(long); + struct cma *cma; + + pr_debug("%s(0x%08lx+0x%lx)\n", __func__, base_pfn, count); + + cma = kmalloc(sizeof *cma, GFP_KERNEL); + if (!cma) + return ERR_PTR(-ENOMEM); + + cma->base_pfn = base_pfn; + cma->count = count; + cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL); + + if (!cma->bitmap) + goto no_mem; + + __cma_activate_area(base_pfn, count); + + pr_debug("%s: returning <%p>\n", __func__, (void *)cma); + return cma; + +no_mem: + kfree(cma); + return ERR_PTR(-ENOMEM); +} + +static struct cma_reserved { + phys_addr_t start; + unsigned long size; + struct device *dev; +} cma_reserved[MAX_CMA_AREAS] __initdata; +static unsigned cma_reserved_count __initdata; + +static int __init __cma_init_reserved_areas(void) +{ + struct cma_reserved *r = cma_reserved; + unsigned i = cma_reserved_count; + + pr_debug("%s()\n", __func__); + + for (; i; --i, ++r) { + struct cma *cma; + cma = __cma_create_area(phys_to_pfn(r->start), + r->size >> PAGE_SHIFT); + if (!IS_ERR(cma)) { + pr_debug("%s: created area %p\n", __func__, cma); + if (r->dev) + set_dev_cma_area(r->dev, cma); + else + dma_contiguous_default_area = cma; + } + } + return 0; +} +core_initcall(__cma_init_reserved_areas); + +/** + * dma_declare_contiguous() - reserve area for contiguous memory handling + * for particular device + * @dev: Pointer to device structure. + * @size: Size of the reserved memory. + * @start: Start address of the reserved memory (optional, 0 for any). + * + * This funtion reserves memory for specified device. It should be + * called by board specific code when early allocator (memblock or bootmem) + * is still activate. + */ +int __init dma_declare_contiguous(struct device *dev, unsigned long size, + phys_addr_t base) +{ + struct cma_reserved *r = &cma_reserved[cma_reserved_count]; + unsigned long alignment; + + pr_debug("%s(%p+%p)\n", __func__, (void *)base, (void *)size); + + /* Sanity checks */ + if (cma_reserved_count == ARRAY_SIZE(cma_reserved)) + return -ENOSPC; + + if (!size) + return -EINVAL; + + /* Sanitise input arguments */ + alignment = PAGE_SIZE << (MAX_ORDER + 1); + base = ALIGN(base, alignment); + size = ALIGN(size , alignment); + + /* Reserve memory */ + if (base) { + if (memblock_is_region_reserved(base, size) || + memblock_reserve(base, size) < 0) + return -EBUSY; + } else { + /* + * Use __memblock_alloc_base() since + * memblock_alloc_base() panic()s. + */ + phys_addr_t addr = __memblock_alloc_base(size, alignment, 0); + if (!addr) { + return -ENOMEM; + } else if (addr + size > ~(unsigned long)0) { + memblock_free(addr, size); + return -EOVERFLOW; + } else { + base = addr; + } + } + + /* + * Each reserved area must be initialised later, when more kernel + * subsystems (like slab allocator) are available. + */ + r->start = base; + r->size = size; + r->dev = dev; + cma_reserved_count++; + printk(KERN_INFO "%s: reserved %ld MiB area at 0x%p\n", __func__, + size / SZ_1M, (void *)base); + + /* + * Architecture specific contiguous memory fixup. + */ + dma_contiguous_early_fixup(base, size); + return 0; +} + +/** + * dma_alloc_from_contiguous() - allocate pages from contiguous area + * @dev: Pointer to device for which the allocation is performed. + * @count: Requested number of pages. + * @align: Requested alignment of pages (in PAGE_SIZE order). + * + * This funtion allocates memory buffer for specified device. It uses + * device specific contiguous memory area if available or the default + * global one. Requires architecture specific get_dev_cma_area() helper + * function. + */ +struct page *dma_alloc_from_contiguous(struct device *dev, int count, + unsigned int order) +{ + struct cma *cma = get_dev_cma_area(dev); + unsigned long pfn, pageno; + unsigned int align; + int ret; + + if (!cma) + return NULL; + + if (order > CONFIG_CMA_ALIGNMENT) + order = CONFIG_CMA_ALIGNMENT; + + pr_debug("%s(<%p>, %d/%d)\n", __func__, (void *)cma, count, order); + + align = (1 << order) - 1; + + if (!count) + return NULL; + + mutex_lock(&cma_mutex); + + pageno = bitmap_find_next_zero_area(cma->bitmap, cma->count, 0, count, + align); + if (pageno >= cma->count) { + ret = -ENOMEM; + goto error; + } + bitmap_set(cma->bitmap, pageno, count); + + pfn = cma->base_pfn + pageno; + ret = alloc_contig_range(pfn, pfn + count, 0, MIGRATE_CMA); + if (ret) + goto free; + + mutex_unlock(&cma_mutex); + + pr_debug("%s(): returning [%p]\n", __func__, pfn_to_page(pfn)); + return pfn_to_page(pfn); +free: + bitmap_clear(cma->bitmap, pageno, count); +error: + mutex_unlock(&cma_mutex); + return NULL; +} + +/** + * dma_release_from_contiguous() - release allocated pages + * @dev: Pointer to device for which the pages were allocated. + * @pages: Allocated pages. + * @count: Number of allocated pages. + * + * This funtion releases memory allocated by dma_alloc_from_contiguous(). + * It return 0 when provided pages doen't belongs to contiguous area and + * 1 on success. + */ +int dma_release_from_contiguous(struct device *dev, struct page *pages, + int count) +{ + struct cma *cma = get_dev_cma_area(dev); + unsigned long pfn; + + if (!cma || !pages) + return 0; + + pr_debug("%s([%p])\n", __func__, (void *)pages); + + pfn = page_to_pfn(pages); + + if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count) + return 0; + + mutex_lock(&cma_mutex); + + bitmap_clear(cma->bitmap, pfn - cma->base_pfn, count); + free_contig_pages(pages, count); + + mutex_unlock(&cma_mutex); + return 1; +} diff --git a/include/linux/dma-contiguous.h b/include/linux/dma-contiguous.h new file mode 100644 index 0000000..6f8e462 --- /dev/null +++ b/include/linux/dma-contiguous.h @@ -0,0 +1,102 @@ +#ifndef __LINUX_CMA_H +#define __LINUX_CMA_H + +/* + * Contiguous Memory Allocator for DMA mapping framework + * Copyright (c) 2010-2011 by Samsung Electronics. + * Written by: + * Marek Szyprowski <m.szyprowski@samsung.com> + * Michal Nazarewicz <mina86@mina86.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of the + * License or (at your optional) any later version of the license. + */ + +/* + * Contiguous Memory Allocator + * + * The Contiguous Memory Allocator (CMA) makes it possible to + * allocate big contiguous chunks of memory after the system has + * booted. + * + * Why is it needed? + * + * Various devices on embedded systems have no scatter-getter and/or + * IO map support and require contiguous blocks of memory to + * operate. They include devices such as cameras, hardware video + * coders, etc. + * + * Such devices often require big memory buffers (a full HD frame + * is, for instance, more then 2 mega pixels large, i.e. more than 6 + * MB of memory), which makes mechanisms such as kmalloc() or + * alloc_page() ineffective. + * + * At the same time, a solution where a big memory region is + * reserved for a device is suboptimal since often more memory is + * reserved then strictly required and, moreover, the memory is + * inaccessible to page system even if device drivers don't use it. + * + * CMA tries to solve this issue by operating on memory regions + * where only movable pages can be allocated from. This way, kernel + * can use the memory for pagecache and when device driver requests + * it, allocated pages can be migrated. + * + * Driver usage + * + * CMA should not be used by the device drivers directly. It is + * only a helper framework for dma-mapping subsystem. + * + * For more information, see kernel-docs in drivers/base/dma-contiguous.c + */ + +#ifdef __KERNEL__ + +struct cma; +struct page; +struct device; + +extern struct cma *dma_contiguous_default_area; + +#ifdef CONFIG_CMA + +void dma_contiguous_reserve(void); +int dma_declare_contiguous(struct device *dev, unsigned long size, + phys_addr_t base); + +struct page *dma_alloc_from_contiguous(struct device *dev, int count, + unsigned int order); +int dma_release_from_contiguous(struct device *dev, struct page *pages, + int count); + +#else + +static inline void dma_contiguous_reserve(void) { } + +static inline +int dma_declare_contiguous(struct device *dev, unsigned long size, + unsigned long base) +{ + return -EINVAL; +} + +static inline +struct page *dma_alloc_from_contiguous(struct device *dev, int count, + unsigned int order) +{ + return NULL; +} + +static inline +int dma_release_from_contiguous(struct device *dev, struct page *pages, + int count) +{ + return 0; +} + +#endif + +#endif + +#endif -- 1.7.1.569.g6f426 ^ permalink raw reply related [flat|nested] 46+ messages in thread
* [PATCHv11 0/8] Contiguous Memory Allocator @ 2011-07-05 7:41 Marek Szyprowski 2011-07-05 7:41 ` [PATCH 6/8] drivers: add " Marek Szyprowski 0 siblings, 1 reply; 46+ messages in thread From: Marek Szyprowski @ 2011-07-05 7:41 UTC (permalink / raw) To: linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig Cc: Michal Nazarewicz, Marek Szyprowski, Kyungmin Park, Andrew Morton, KAMEZAWA Hiroyuki, Ankita Garg, Daniel Walker, Mel Gorman, Arnd Bergmann, Jesse Barker, Jonathan Corbet, Chunsang Jeong Hello everyone, This is yet another round of Contiguous Memory Allocator patches. I hope that I've managed to resolve all the items discussed during the Memory Management summit at Linaro Meeting in Budapest and pointed later on mailing lists. The goal is to integrate it as tight as possible with other kernel subsystems (like memory management and dma-mapping) and finally merge to mainline. Previous version introduced integration with DMA-mapping subsystem for ARM architecture. In this version I've cleaned up it even more and prepared for easier integration on other than ARM architectures. I've also rebased all the code onto latest v3.0-rc6 kernel. A few words for these who see CMA for the first time: The Contiguous Memory Allocator (CMA) makes it possible for device drivers to allocate big contiguous chunks of memory after the system has booted. The main difference from the similar frameworks is the fact that CMA allows to transparently reuse memory region reserved for the big chunk allocation as a system memory, so no memory is wasted when no big chunk is allocated. Once the alloc request is issued, the framework will migrate system pages to create a required big chunk of physically contiguous memory. For more information you can refer to nice LWN article: http://lwn.net/Articles/447405/ and links to previous versions of CMA framework. The CMA framework has been initially developed by Michal Nazarewicz at Samsung Poland R&D Center. Since version 9, I've taken over the development, because Michal has left the company. The current version of CMA is a set of helper functions for DMA mapping framework that handles allocation of contiguous memory blocks. The difference between this patchset and Kamezawa's alloc_contig_pages() are: 1. alloc_contig_pages() requires MAX_ORDER alignment of allocations which may be unsuitable for embeded systems where a few MiBs are required. Lack of the requirement on the alignment means that several threads might try to access the same pageblock/page. To prevent this from happening CMA uses a mutex so that only one allocating/releasing function may run at one point. 2. CMA may use its own migratetype (MIGRATE_CMA) which behaves similarly to ZONE_MOVABLE but can be put in arbitrary places. This is required for us since we need to define two disjoint memory ranges inside system RAM. (ie. in two memory banks (do not confuse with nodes)). 3. alloc_contig_pages() scans memory in search for range that could be migrated. CMA on the other hand maintains its own allocator to decide where to allocate memory for device drivers and then tries to migrate pages from that part if needed. This is not strictly required but I somehow feel it might be faster. The integration with ARM DMA-mapping subsystem is quite straightforward. Once cma context is available alloc_pages() can be replaced by dma_alloc_from_contiguous() call. Current version have been tested on Samsung S5PC110 based Goni machine and s5p-fimc V4L2 driver. The driver itself uses videobuf2 dma-contig memory allocator, which in turn relies on dma_alloc_coherent() from DMA-mapping subsystem. By integrating CMA with DMA-mapping we managed to get this driver working with CMA without any single change required in the driver or videobuf2-dma-contig allocator. TODO: - resolve double-mapping issues with ARMv6+ and coherent memory Best regards -- Marek Szyprowski Samsung Poland R&D Center Links to previous versions of the patchset: v10: <http://www.spinics.net/lists/linux-mm/msg20761.html> v9: <http://article.gmane.org/gmane.linux.kernel.mm/60787> v8: <http://article.gmane.org/gmane.linux.kernel.mm/56855> v7: <http://article.gmane.org/gmane.linux.kernel.mm/55626> v6: <http://article.gmane.org/gmane.linux.kernel.mm/55626> v5: (intentionally left out as CMA v5 was identical to CMA v4) v4: <http://article.gmane.org/gmane.linux.kernel.mm/52010> v3: <http://article.gmane.org/gmane.linux.kernel.mm/51573> v2: <http://article.gmane.org/gmane.linux.kernel.mm/50986> v1: <http://article.gmane.org/gmane.linux.kernel.mm/50669> Changelog: v11: 1. Removed genalloc usage and replaced it with direct calls to bitmap_* functions, dropped patches that are not needed anymore (genalloc extensions) 2. Moved all contiguous area management code from mm/cma.c to drivers/base/dma-contiguous.c 3. Renamed cm_alloc/free to dma_alloc/release_from_contiguous 4. Introduced global, system wide (default) contiguous area configured with kernel config and kernel cmdline parameters 5. Simplified initialization to just one function: dma_declare_contiguous() 6. Added example of device private memory contiguous area v10: 1. Rebased onto 3.0-rc2 and resolved all conflicts 2. Simplified CMA to be just a pure memory allocator, for use with platfrom/bus specific subsystems, like dma-mapping. Removed all device specific functions are calls. 3. Integrated with ARM DMA-mapping subsystem. 4. Code cleanup here and there. 5. Removed private context support. v9: 1. Rebased onto 2.6.39-rc1 and resolved all conflicts 2. Fixed a bunch of nasty bugs that happened when the allocation failed (mainly kernel oops due to NULL ptr dereference). 3. Introduced testing code: cma-regions compatibility layer and videobuf2-cma memory allocator module. v8: 1. The alloc_contig_range() function has now been separated from CMA and put in page_allocator.c. This function tries to migrate all LRU pages in specified range and then allocate the range using alloc_contig_freed_pages(). 2. Support for MIGRATE_CMA has been separated from the CMA code. I have not tested if CMA works with ZONE_MOVABLE but I see no reasons why it shouldn't. 3. I have added a @private argument when creating CMA contexts so that one can reserve memory and not share it with the rest of the system. This way, CMA acts only as allocation algorithm. v7: 1. A lot of functionality that handled driver->allocator_context mapping has been removed from the patchset. This is not to say that this code is not needed, it's just not worth posting everything in one patchset. Currently, CMA is "just" an allocator. It uses it's own migratetype (MIGRATE_CMA) for defining ranges of pageblokcs which behave just like ZONE_MOVABLE but dispite the latter can be put in arbitrary places. 2. The migration code that was introduced in the previous version actually started working. v6: 1. Most importantly, v6 introduces support for memory migration. The implementation is not yet complete though. Migration support means that when CMA is not using memory reserved for it, page allocator can allocate pages from it. When CMA wants to use the memory, the pages have to be moved and/or evicted as to make room for CMA. To make it possible it must be guaranteed that only movable and reclaimable pages are allocated in CMA controlled regions. This is done by introducing a MIGRATE_CMA migrate type that guarantees exactly that. Some of the migration code is "borrowed" from Kamezawa Hiroyuki's alloc_contig_pages() implementation. The main difference is that thanks to MIGRATE_CMA migrate type CMA assumes that memory controlled by CMA are is always movable or reclaimable so that it makes allocation decisions regardless of the whether some pages are actually allocated and migrates them if needed. The most interesting patches from the patchset that implement the functionality are: 09/13: mm: alloc_contig_free_pages() added 10/13: mm: MIGRATE_CMA migration type added 11/13: mm: MIGRATE_CMA isolation functions added 12/13: mm: cma: Migration support added [wip] Currently, kernel panics in some situations which I am trying to investigate. 2. cma_pin() and cma_unpin() functions has been added (after a conversation with Johan Mossberg). The idea is that whenever hardware does not use the memory (no transaction is on) the chunk can be moved around. This would allow defragmentation to be implemented if desired. No defragmentation algorithm is provided at this time. 3. Sysfs support has been replaced with debugfs. I always felt unsure about the sysfs interface and when Greg KH pointed it out I finally got to rewrite it to debugfs. v5: (intentionally left out as CMA v5 was identical to CMA v4) v4: 1. The "asterisk" flag has been removed in favour of requiring that platform will provide a "*=<regions>" rule in the map attribute. 2. The terminology has been changed slightly renaming "kind" to "type" of memory. In the previous revisions, the documentation indicated that device drivers define memory kinds and now, v3: 1. The command line parameters have been removed (and moved to a separate patch, the fourth one). As a consequence, the cma_set_defaults() function has been changed -- it no longer accepts a string with list of regions but an array of regions. 2. The "asterisk" attribute has been removed. Now, each region has an "asterisk" flag which lets one specify whether this region should by considered "asterisk" region. 3. SysFS support has been moved to a separate patch (the third one in the series) and now also includes list of regions. v2: 1. The "cma_map" command line have been removed. In exchange, a SysFS entry has been created under kernel/mm/contiguous. The intended way of specifying the attributes is a cma_set_defaults() function called by platform initialisation code. "regions" attribute (the string specified by "cma" command line parameter) can be overwritten with command line parameter; the other attributes can be changed during run-time using the SysFS entries. 2. The behaviour of the "map" attribute has been modified slightly. Currently, if no rule matches given device it is assigned regions specified by the "asterisk" attribute. It is by default built from the region names given in "regions" attribute. 3. Devices can register private regions as well as regions that can be shared but are not reserved using standard CMA mechanisms. A private region has no name and can be accessed only by devices that have the pointer to it. 4. The way allocators are registered has changed. Currently, a cma_allocator_register() function is used for that purpose. Moreover, allocators are attached to regions the first time memory is registered from the region or when allocator is registered which means that allocators can be dynamic modules that are loaded after the kernel booted (of course, it won't be possible to allocate a chunk of memory from a region if allocator is not loaded). 5. Index of new functions: +static inline dma_addr_t __must_check +cma_alloc_from(const char *regions, size_t size, + dma_addr_t alignment) +static inline int +cma_info_about(struct cma_info *info, const const char *regions) +int __must_check cma_region_register(struct cma_region *reg); +dma_addr_t __must_check +cma_alloc_from_region(struct cma_region *reg, + size_t size, dma_addr_t alignment); +static inline dma_addr_t __must_check +cma_alloc_from(const char *regions, + size_t size, dma_addr_t alignment); +int cma_allocator_register(struct cma_allocator *alloc); Patches in this patchset: mm: move some functions from memory_hotplug.c to page_isolation.c mm: alloc_contig_freed_pages() added Code "stolen" from Kamezawa. The first patch just moves code around and the second provide function for "allocates" already freed memory. mm: alloc_contig_range() added This is what Kamezawa asked: a function that tries to migrate all pages from given range and then use alloc_contig_freed_pages() (defined by the previous commit) to allocate those pages. mm: MIGRATE_CMA migration type added mm: MIGRATE_CMA isolation functions added Introduction of the new migratetype and support for it in CMA. MIGRATE_CMA works similar to ZONE_MOVABLE expect almost any memory range can be marked as one. mm: cma: Contiguous Memory Allocator added The code CMA code. Manages CMA contexts and performs memory allocations. ARM: integrate CMA with dma-mapping subsystem Main client of CMA frame work. CMA serves as a alloc_pages() replacement. ARM: S5PV210: example of CMA private area for FIMC device on Goni board Example of platform/board specific code that creates cma context and assigns it to particular device. Patch summary: KAMEZAWA Hiroyuki (2): mm: move some functions from memory_hotplug.c to page_isolation.c mm: alloc_contig_freed_pages() added Marek Szyprowski (3): drivers: add Contiguous Memory Allocator ARM: integrate CMA with dma-mapping subsystem ARM: S5PV210: example of CMA private area for FIMC device on Goni board Michal Nazarewicz (3): mm: alloc_contig_range() added mm: MIGRATE_CMA migration type added mm: MIGRATE_CMA isolation functions added arch/arm/Kconfig | 1 + arch/arm/include/asm/device.h | 3 + arch/arm/include/asm/dma-mapping.h | 20 ++ arch/arm/mach-s5pv210/Kconfig | 1 + arch/arm/mach-s5pv210/mach-goni.c | 7 + arch/arm/mm/dma-mapping.c | 51 ++++-- arch/arm/mm/init.c | 3 + drivers/base/Kconfig | 77 ++++++++ drivers/base/Makefile | 1 + drivers/base/dma-contiguous.c | 367 ++++++++++++++++++++++++++++++++++++ include/linux/dma-contiguous.h | 104 ++++++++++ include/linux/mmzone.h | 43 ++++- include/linux/page-isolation.h | 54 ++++-- mm/Kconfig | 8 +- mm/compaction.c | 10 + mm/memory_hotplug.c | 111 ----------- mm/page_alloc.c | 293 ++++++++++++++++++++++++++--- mm/page_isolation.c | 130 ++++++++++++- 18 files changed, 1112 insertions(+), 172 deletions(-) create mode 100644 drivers/base/dma-contiguous.c create mode 100644 include/linux/dma-contiguous.h -- 1.7.1.569.g6f426 ^ permalink raw reply [flat|nested] 46+ messages in thread
* [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-05 7:41 [PATCHv11 0/8] " Marek Szyprowski @ 2011-07-05 7:41 ` Marek Szyprowski 2011-07-05 10:24 ` Marek Szyprowski ` (2 more replies) 0 siblings, 3 replies; 46+ messages in thread From: Marek Szyprowski @ 2011-07-05 7:41 UTC (permalink / raw) To: linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig Cc: Michal Nazarewicz, Marek Szyprowski, Kyungmin Park, Andrew Morton, KAMEZAWA Hiroyuki, Ankita Garg, Daniel Walker, Mel Gorman, Arnd Bergmann, Jesse Barker, Jonathan Corbet, Chunsang Jeong The Contiguous Memory Allocator is a set of helper functions for DMA mapping framework that improves allocations of contiguous memory chunks. CMA grabs memory on system boot, marks it with CMA_MIGRATE_TYPE and gives back to the system. Kernel is allowed to allocate movable pages within CMA's managed memory so that it can be used for example for page cache when DMA mapping do not use it. On dma_alloc_from_contiguous() request such pages are migrated out of CMA area to free required contiguous block and fulfill the request. This allows to allocate large contiguous chunks of memory at any time assuming that there is enough free memory available in the system. This code is heavily based on earlier works by Michal Nazarewicz. Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> CC: Michal Nazarewicz <mina86@mina86.com> --- drivers/base/Kconfig | 77 +++++++++ drivers/base/Makefile | 1 + drivers/base/dma-contiguous.c | 367 ++++++++++++++++++++++++++++++++++++++++ include/linux/dma-contiguous.h | 104 +++++++++++ 4 files changed, 549 insertions(+), 0 deletions(-) create mode 100644 drivers/base/dma-contiguous.c create mode 100644 include/linux/dma-contiguous.h diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig index d57e8d0..95ae1a7 100644 --- a/drivers/base/Kconfig +++ b/drivers/base/Kconfig @@ -168,4 +168,81 @@ config SYS_HYPERVISOR bool default n +config CMA + bool "Contiguous Memory Allocator" + depends HAVE_DMA_CONTIGUOUS && HAVE_MEMBLOCK + select MIGRATION + select CMA_MIGRATE_TYPE + help + This enables the Contiguous Memory Allocator which allows drivers + to allocate big physically-contiguous blocks of memory for use with + hardware components that do not support I/O map nor scatter-gather. + + For more information see <include/linux/dma-contiguous.h>. + If unsure, say "n". + +if CMA + +config CMA_DEBUG + bool "CMA debug messages (DEVELOPEMENT)" + help + Turns on debug messages in CMA. This produces KERN_DEBUG + messages for every CMA call as well as various messages while + processing calls such as dma_alloc_from_contiguous(). + This option does not affect warning and error messages. + +comment "Default contiguous memory area size:" + +config CMA_SIZE_ABSOLUTE + int "Absolute size (in MiB)" + default 16 + help + Defines the size (in MiB) of the default memory area for Contiguous + Memory Allocator. + +config CMA_SIZE_PERCENTAGE + int "Percentage of total memory" + default 10 + help + Defines the size of the default memory area for Contiguous Memory + Allocator as a percentage of the total memory in the system. + +choice + prompt "Selected region size" + default CMA_SIZE_SEL_ABSOLUTE + +config CMA_SIZE_SEL_ABSOLUTE + bool "Use absolute value only" + +config CMA_SIZE_SEL_PERCENTAGE + bool "Use percentage value only" + +config CMA_SIZE_SEL_MIN + bool "Use lower value (minimum)" + +config CMA_SIZE_SEL_MAX + bool "Use higher value (maximum)" + +endchoice + +config CMA_ALIGNMENT + int "Maximum PAGE_SIZE order of alignment for contiguous buffers" + range 4 9 + default 8 + help + DMA mapping framework by default aligns all buffers to the smallest + PAGE_SIZE order which is greater than or equal to the requested buffer + size. This works well for buffers up to a few hundreds kilobytes, but + for larger buffers it just a memory waste. With this parameter you can + specify the maximum PAGE_SIZE order for contiguous buffers. Larger + buffers will be aligned only to this specified order. The order is + expressed as a power of two multiplied by the PAGE_SIZE. + + For example, if your system defaults to 4KiB pages, the order value + of 8 means that the buffers will be aligned up to 1MiB only. + + If unsure, leave the default value "8". + +endif + endmenu diff --git a/drivers/base/Makefile b/drivers/base/Makefile index 4c5701c..be6aab4 100644 --- a/drivers/base/Makefile +++ b/drivers/base/Makefile @@ -5,6 +5,7 @@ obj-y := core.o sys.o bus.o dd.o syscore.o \ cpu.o firmware.o init.o map.o devres.o \ attribute_container.o transport_class.o obj-$(CONFIG_DEVTMPFS) += devtmpfs.o +obj-$(CONFIG_CMA) += dma-contiguous.o obj-y += power/ obj-$(CONFIG_HAS_DMA) += dma-mapping.o obj-$(CONFIG_HAVE_GENERIC_DMA_COHERENT) += dma-coherent.o diff --git a/drivers/base/dma-contiguous.c b/drivers/base/dma-contiguous.c new file mode 100644 index 0000000..707b901 --- /dev/null +++ b/drivers/base/dma-contiguous.c @@ -0,0 +1,367 @@ +/* + * Contiguous Memory Allocator for DMA mapping framework + * Copyright (c) 2010-2011 by Samsung Electronics. + * Written by: + * Marek Szyprowski <m.szyprowski@samsung.com> + * Michal Nazarewicz <mina86@mina86.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of the + * License or (at your optional) any later version of the license. + */ + +#define pr_fmt(fmt) "cma: " fmt + +#ifdef CONFIG_CMA_DEBUG +#ifndef DEBUG +# define DEBUG +#endif +#endif + +#include <asm/page.h> +#include <asm/sizes.h> + +#include <linux/memblock.h> +#include <linux/err.h> +#include <linux/mm.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/page-isolation.h> +#include <linux/slab.h> +#include <linux/swap.h> +#include <linux/mm_types.h> +#include <linux/dma-mapping.h> +#include <linux/dma-contiguous.h> + +struct cma { + unsigned long base_pfn; + unsigned long count; + unsigned long *bitmap; +}; + +struct cma *dma_contiguous_default_area; + +static unsigned long size_abs = CONFIG_CMA_SIZE_ABSOLUTE * SZ_1M; +static unsigned long size_percent = CONFIG_CMA_SIZE_PERCENTAGE; +static long size_cmdline = -1; + +static int __init early_cma(char *p) +{ + pr_debug("%s(%s)\n", __func__, p); + size_cmdline = memparse(p, &p); + return 0; +} +early_param("cma", early_cma); + +/** + * dma_contiguous_reserve() - reserve area for contiguous memory handling + * + * This funtion reserves memory from memblock subsystem. It should be + * called by arch specific code once a memblock allocator has been activated + * and all other subsystems have already allocated/reserved memory. + */ +void __init dma_contiguous_reserve(void) +{ + struct memblock_region *reg; + unsigned long selected_size = 0; + unsigned long total_pages = 0; + + pr_debug("%s()\n", __func__); + + /* + * We cannot use memblock_phys_mem_size() here, because + * memblock_analyze() has not been called yet. + */ + for_each_memblock(memory, reg) + total_pages += memblock_region_memory_end_pfn(reg) - + memblock_region_memory_base_pfn(reg); + + size_percent *= (total_pages << PAGE_SHIFT) / 100; + + pr_debug("%s: available phys mem: %ld MiB\n", __func__, + (total_pages << PAGE_SHIFT) / SZ_1M); + +#ifdef CONFIG_CMA_SIZE_SEL_ABSOLUTE + selected_size = size_abs; +#endif +#ifdef CONFIG_CMA_SIZE_SEL_PERCENTAGE + selected_size = size_percent; +#endif +#ifdef CONFIG_CMA_SIZE_SEL_MIN + selected_size = min(size_abs, size_percent); +#endif +#ifdef CONFIG_CMA_SIZE_SEL_MAX + selected_size = max(size_abs, size_percent); +#endif + + if (size_cmdline != -1) + selected_size = size_cmdline; + + if (!selected_size) + return; + + pr_debug("%s: reserving %ld MiB for global area\n", __func__, + selected_size / SZ_1M); + + dma_declare_contiguous(NULL, selected_size, 0); +}; + +static DEFINE_MUTEX(cma_mutex); + +#ifdef CONFIG_DEBUG_VM + +static int __cma_activate_area(unsigned long base_pfn, unsigned long count) +{ + unsigned long pfn = base_pfn; + unsigned i = count; + struct zone *zone; + + pr_debug("%s(0x%08lx+0x%lx)\n", __func__, base_pfn, count); + + VM_BUG_ON(!pfn_valid(pfn)); + zone = page_zone(pfn_to_page(pfn)); + + do { + VM_BUG_ON(!pfn_valid(pfn)); + VM_BUG_ON(page_zone(pfn_to_page(pfn)) != zone); + if (!(pfn & (pageblock_nr_pages - 1))) + init_cma_reserved_pageblock(pfn_to_page(pfn)); + ++pfn; + } while (--i); + + return 0; +} + +#else + +static int __cma_activate_area(unsigned long base_pfn, unsigned long count) +{ + unsigned i = count >> pageblock_order; + struct page *p = pfn_to_page(base_pfn); + + pr_debug("%s(0x%08lx+0x%lx)\n", __func__, base_pfn, count); + + do { + init_cma_reserved_pageblock(p); + p += pageblock_nr_pages; + } while (--i); + + return 0; +} + +#endif + +static struct cma *__cma_create_area(unsigned long base_pfn, + unsigned long count) +{ + int bitmap_size = BITS_TO_LONGS(count) * sizeof(long); + struct cma *cma; + + pr_debug("%s(0x%08lx+0x%lx)\n", __func__, base_pfn, count); + + cma = kmalloc(sizeof *cma, GFP_KERNEL); + if (!cma) + return ERR_PTR(-ENOMEM); + + cma->base_pfn = base_pfn; + cma->count = count; + cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL); + + if (!cma->bitmap) + goto no_mem; + + __cma_activate_area(base_pfn, count); + + pr_debug("%s: returning <%p>\n", __func__, (void *)cma); + return cma; + +no_mem: + kfree(cma); + return ERR_PTR(-ENOMEM); +} + +static struct cma_reserved { + unsigned long start; + unsigned long size; + struct device *dev; +} cma_reserved[8] __initdata; +static unsigned cma_reserved_count __initdata; + +static int __init __cma_init_reserved_areas(void) +{ + struct cma_reserved *r = cma_reserved; + unsigned i = cma_reserved_count; + + pr_debug("%s()\n", __func__); + + for (; i; --i, ++r) { + struct cma *cma; + cma = __cma_create_area(page_to_pfn(phys_to_page(r->start)), + r->size >> PAGE_SHIFT); + if (!IS_ERR(cma)) { + pr_debug("%s: created area %p\n", __func__, cma); + if (r->dev) + set_dev_cma_area(r->dev, cma); + else + dma_contiguous_default_area = cma; + } + } + return 0; +} +core_initcall(__cma_init_reserved_areas); + +/** + * dma_declare_contiguous() - reserve area for contiguous memory handling + * for particular device + * @dev: Pointer to device structure. + * @size: Size of the reserved memory. + * @start: Start address of the reserved memory (optional, 0 for any). + * + * This funtion reserves memory for specified device. It should be + * called by board specific code once a memblock allocator has been activated + * and all other subsystems have already allocated/reserved memory. + */ +int __init dma_declare_contiguous(struct device *dev, unsigned long size, + phys_addr_t start) +{ + struct cma_reserved *r = &cma_reserved[cma_reserved_count]; + unsigned long alignment; + + pr_debug("%s(%p+%p)\n", __func__, (void *)start, (void *)size); + + /* Sanity checks */ + if (cma_reserved_count == ARRAY_SIZE(cma_reserved)) + return -ENOSPC; + + if (!size) + return -EINVAL; + + /* Sanitise input arguments */ + alignment = PAGE_SIZE << (MAX_ORDER + 1); + start = ALIGN(start, alignment); + size = ALIGN(size , alignment); + + /* Reserve memory */ + if (start) { + if (memblock_is_region_reserved(start, size) || + memblock_reserve(start, size) < 0) + return -EBUSY; + } else { + /* + * Use __memblock_alloc_base() since + * memblock_alloc_base() panic()s. + */ + u64 addr = __memblock_alloc_base(size, alignment, 0); + if (!addr) { + return -ENOMEM; + } else if (addr + size > ~(unsigned long)0) { + memblock_free(addr, size); + return -EOVERFLOW; + } else { + start = addr; + } + } + + /* + * Each reserved area must be initialised later, when more kernel + * subsystems (like slab allocator) are available. + */ + r->start = start; + r->size = size; + r->dev = dev; + cma_reserved_count++; + printk(KERN_INFO "%s: reserved %ld MiB area at 0x%p\n", __func__, + size / SZ_1M, (void *)start); + return 0; +} + +/** + * dma_alloc_from_contiguous() - allocate pages from contiguous area + * @dev: Pointer to device for which the allocation is performed. + * @count: Requested number of pages. + * @align: Requested alignment of pages (in PAGE_SIZE order). + * + * This funtion allocates memory buffer for specified device. It uses + * device specific contiguous memory area if available or the default + * global one. Requires architecture specific get_dev_cma_area() helper + * function. + */ +struct page *dma_alloc_from_contiguous(struct device *dev, int count, + unsigned int align) +{ + struct cma *cma = get_dev_cma_area(dev); + unsigned long pfn, pageno; + int ret; + + if (!cma) + return NULL; + + if (align > CONFIG_CMA_ALIGNMENT) + align = CONFIG_CMA_ALIGNMENT; + + pr_debug("%s(<%p>, %d/%d)\n", __func__, (void *)cma, count, align); + + if (!count) + return NULL; + + mutex_lock(&cma_mutex); + + pageno = bitmap_find_next_zero_area(cma->bitmap, cma->count, 0, count, + align); + if (pageno >= cma->count) { + ret = -ENOMEM; + goto error; + } + bitmap_set(cma->bitmap, pageno, count); + + pfn = cma->base_pfn + pageno; + ret = alloc_contig_range(pfn, pfn + count, 0, MIGRATE_CMA); + if (ret) + goto free; + + mutex_unlock(&cma_mutex); + + pr_debug("%s(): returning [%ld]\n", __func__, pfn); + return pfn_to_page(pfn); +free: + bitmap_clear(cma->bitmap, pageno, count); +error: + mutex_unlock(&cma_mutex); + return NULL; +} + +/** + * dma_release_from_contiguous() - release allocated pages + * @dev: Pointer to device for which the pages were allocated. + * @pages: Allocated pages. + * @count: Number of allocated pages. + * + * This funtion reserves memory for specified device. It should be + * called by board specific code once a memblock allocator has been activated + * and all other subsystems have already allocated/reserved memory. + */ +int dma_release_from_contiguous(struct device *dev, struct page *pages, + int count) +{ + struct cma *cma = get_dev_cma_area(dev); + unsigned long pfn; + + if (!cma || !pages) + return 0; + + pr_debug("%s([%p])\n", __func__, (void *)pages); + + pfn = page_to_pfn(pages); + + if (pfn < cma->base_pfn || pfn >= cma->base_pfn + count) + return 0; + + mutex_lock(&cma_mutex); + + bitmap_clear(cma->bitmap, pfn - cma->base_pfn, count); + free_contig_pages(pages, count); + + mutex_unlock(&cma_mutex); + return 1; +} diff --git a/include/linux/dma-contiguous.h b/include/linux/dma-contiguous.h new file mode 100644 index 0000000..98312c9 --- /dev/null +++ b/include/linux/dma-contiguous.h @@ -0,0 +1,104 @@ +#ifndef __LINUX_CMA_H +#define __LINUX_CMA_H + +/* + * Contiguous Memory Allocator for DMA mapping framework + * Copyright (c) 2010-2011 by Samsung Electronics. + * Written by: + * Marek Szyprowski <m.szyprowski@samsung.com> + * Michal Nazarewicz <mina86@mina86.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of the + * License or (at your optional) any later version of the license. + */ + +/* + * Contiguous Memory Allocator + * + * The Contiguous Memory Allocator (CMA) makes it possible to + * allocate big contiguous chunks of memory after the system has + * booted. + * + * Why is it needed? + * + * Various devices on embedded systems have no scatter-getter and/or + * IO map support and require contiguous blocks of memory to + * operate. They include devices such as cameras, hardware video + * coders, etc. + * + * Such devices often require big memory buffers (a full HD frame + * is, for instance, more then 2 mega pixels large, i.e. more than 6 + * MB of memory), which makes mechanisms such as kmalloc() or + * alloc_page() ineffective. + * + * At the same time, a solution where a big memory region is + * reserved for a device is suboptimal since often more memory is + * reserved then strictly required and, moreover, the memory is + * inaccessible to page system even if device drivers don't use it. + * + * CMA tries to solve this issue by operating on memory regions + * where only movable pages can be allocated from. This way, kernel + * can use the memory for pagecache and when device driver requests + * it, allocated pages can be migrated. + * + * Driver usage + * + * CMA should not be used by the device drivers directly. It is + * only a helper framework for dma-mapping subsystem. + * + * For more information, see kernel-docs in drivers/base/dma-contiguous.c + */ + +#ifdef __KERNEL__ + +struct cma; +struct page; +struct device; + +#ifdef CONFIG_CMA + +extern struct cma *dma_contiguous_default_area; + +void dma_contiguous_reserve(void); +int dma_declare_contiguous(struct device *dev, unsigned long size, + phys_addr_t base); + +struct page *dma_alloc_from_contiguous(struct device *dev, int count, + unsigned int order); +int dma_release_from_contiguous(struct device *dev, struct page *pages, + int count); + +#else + +#define dna_contiguous_default_area NULL + +static inline void dma_contiguous_reserve(void) { } + +static inline +int dma_declare_contiguous(struct device *dev, unsigned long size, + unsigned long base) +{ + return -EINVAL; +} + +static inline +struct page *dma_alloc_from_contiguous(struct device *dev, int count, + unsigned int order) +{ + return NULL; +} + +static inline +int dma_release_from_contiguous(struct device *dev, struct page *pages, + int count) +{ + return 0; +} + +#endif + +#endif + +#endif -- 1.7.1.569.g6f426 ^ permalink raw reply related [flat|nested] 46+ messages in thread
* RE: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-05 7:41 ` [PATCH 6/8] drivers: add " Marek Szyprowski @ 2011-07-05 10:24 ` Marek Szyprowski 2011-07-05 11:33 ` Russell King - ARM Linux 2011-07-14 12:29 ` Marek Szyprowski 2 siblings, 0 replies; 46+ messages in thread From: Marek Szyprowski @ 2011-07-05 10:24 UTC (permalink / raw) To: Marek Szyprowski, linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig Cc: 'Michal Nazarewicz', 'Kyungmin Park', 'Andrew Morton', 'KAMEZAWA Hiroyuki', 'Ankita Garg', 'Daniel Walker', 'Mel Gorman', 'Arnd Bergmann', 'Jesse Barker', 'Jonathan Corbet', 'Chunsang Jeong' Hello, On Tuesday, July 05, 2011 9:42 AM Marek Szyprowski wrote: > The Contiguous Memory Allocator is a set of helper functions for DMA > mapping framework that improves allocations of contiguous memory chunks. > > CMA grabs memory on system boot, marks it with CMA_MIGRATE_TYPE and > gives back to the system. Kernel is allowed to allocate movable pages > within CMA's managed memory so that it can be used for example for page > cache when DMA mapping do not use it. On dma_alloc_from_contiguous() > request such pages are migrated out of CMA area to free required > contiguous block and fulfill the request. This allows to allocate large > contiguous chunks of memory at any time assuming that there is enough > free memory available in the system. > > This code is heavily based on earlier works by Michal Nazarewicz. > > Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> > Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> > CC: Michal Nazarewicz <mina86@mina86.com> > --- > drivers/base/Kconfig | 77 +++++++++ > drivers/base/Makefile | 1 + > drivers/base/dma-contiguous.c | 367 > ++++++++++++++++++++++++++++++++++++++++ > include/linux/dma-contiguous.h | 104 +++++++++++ > 4 files changed, 549 insertions(+), 0 deletions(-) > create mode 100644 drivers/base/dma-contiguous.c > create mode 100644 include/linux/dma-contiguous.h > > diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig > index d57e8d0..95ae1a7 100644 > --- a/drivers/base/Kconfig > +++ b/drivers/base/Kconfig > @@ -168,4 +168,81 @@ config SYS_HYPERVISOR > bool > default n > > +config CMA > + bool "Contiguous Memory Allocator" > + depends HAVE_DMA_CONTIGUOUS && HAVE_MEMBLOCK The above line should be obviously "depends on HAVE_DMA_CONTIGUOUS && HAVE_MEMBLOCK". I'm sorry for posting broken version. (snipped) Best regards -- Marek Szyprowski Samsung Poland R&D Center ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-05 7:41 ` [PATCH 6/8] drivers: add " Marek Szyprowski 2011-07-05 10:24 ` Marek Szyprowski @ 2011-07-05 11:33 ` Russell King - ARM Linux 2011-07-05 12:27 ` Arnd Bergmann 2011-07-06 13:58 ` Marek Szyprowski 2011-07-14 12:29 ` Marek Szyprowski 2 siblings, 2 replies; 46+ messages in thread From: Russell King - ARM Linux @ 2011-07-05 11:33 UTC (permalink / raw) To: Marek Szyprowski Cc: linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig, Daniel Walker, Arnd Bergmann, Jonathan Corbet, Mel Gorman, Chunsang Jeong, Michal Nazarewicz, Jesse Barker, Kyungmin Park, Ankita Garg, Andrew Morton, KAMEZAWA Hiroyuki On Tue, Jul 05, 2011 at 09:41:48AM +0200, Marek Szyprowski wrote: > The Contiguous Memory Allocator is a set of helper functions for DMA > mapping framework that improves allocations of contiguous memory chunks. > > CMA grabs memory on system boot, marks it with CMA_MIGRATE_TYPE and > gives back to the system. Kernel is allowed to allocate movable pages > within CMA's managed memory so that it can be used for example for page > cache when DMA mapping do not use it. On dma_alloc_from_contiguous() > request such pages are migrated out of CMA area to free required > contiguous block and fulfill the request. This allows to allocate large > contiguous chunks of memory at any time assuming that there is enough > free memory available in the system. > > This code is heavily based on earlier works by Michal Nazarewicz. And how are you addressing the technical concerns about aliasing of cache attributes which I keep bringing up with this and you keep ignoring and telling me that I'm standing in your way. ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-05 11:33 ` Russell King - ARM Linux @ 2011-07-05 12:27 ` Arnd Bergmann 2011-07-05 12:30 ` Russell King - ARM Linux 2011-08-03 17:43 ` James Bottomley 2011-07-06 13:58 ` Marek Szyprowski 1 sibling, 2 replies; 46+ messages in thread From: Arnd Bergmann @ 2011-07-05 12:27 UTC (permalink / raw) To: Russell King - ARM Linux Cc: Marek Szyprowski, linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig, Daniel Walker, Jonathan Corbet, Mel Gorman, Chunsang Jeong, Michal Nazarewicz, Jesse Barker, Kyungmin Park, Ankita Garg, Andrew Morton, KAMEZAWA Hiroyuki, Jesse Barker On Tuesday 05 July 2011, Russell King - ARM Linux wrote: > On Tue, Jul 05, 2011 at 09:41:48AM +0200, Marek Szyprowski wrote: > > The Contiguous Memory Allocator is a set of helper functions for DMA > > mapping framework that improves allocations of contiguous memory chunks. > > > > CMA grabs memory on system boot, marks it with CMA_MIGRATE_TYPE and > > gives back to the system. Kernel is allowed to allocate movable pages > > within CMA's managed memory so that it can be used for example for page > > cache when DMA mapping do not use it. On dma_alloc_from_contiguous() > > request such pages are migrated out of CMA area to free required > > contiguous block and fulfill the request. This allows to allocate large > > contiguous chunks of memory at any time assuming that there is enough > > free memory available in the system. > > > > This code is heavily based on earlier works by Michal Nazarewicz. > > And how are you addressing the technical concerns about aliasing of > cache attributes which I keep bringing up with this and you keep > ignoring and telling me that I'm standing in your way. This is of course an important issue, and it's the one item listed as TODO in the introductory mail that sent. It's also a preexisting problem as far as I can tell, and it needs to be solved in __dma_alloc for both cases, dma_alloc_from_contiguous and __alloc_system_pages as introduced in patch 7. We've discussed this back and forth, and it always comes down to one of two ugly solutions: 1. Put all of the MIGRATE_CMA and pages into highmem and change __alloc_system_pages so it also allocates only from highmem pages. The consequences of this are that we always need to build kernels with highmem enabled and that we have less lowmem on systems that are already small, both of which can be fairly expensive unless you have lots of highmem already. 2. Add logic to unmap pages from the linear mapping, which is very expensive because it forces the use of small pages in the linear mapping (or in parts of it), and possibly means walking all page tables to remove the PTEs on alloc and put them back in on free. I believe that Chunsang Jeong from Linaro is planning to implement both variants and post them for review, so we can decide which one to merge, or even to merge both and make it a configuration option. See also https://blueprints.launchpad.net/linaro-mm-sig/+spec/engr-mm-dma-mapping-2011.07 I don't think we need to make merging the CMA patches depending on the other patches, it's clear that both need to be solved, and they are independent enough. Arnd ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-05 12:27 ` Arnd Bergmann @ 2011-07-05 12:30 ` Russell King - ARM Linux 2011-07-05 13:58 ` Arnd Bergmann 2011-08-03 17:43 ` James Bottomley 1 sibling, 1 reply; 46+ messages in thread From: Russell King - ARM Linux @ 2011-07-05 12:30 UTC (permalink / raw) To: Arnd Bergmann Cc: Marek Szyprowski, linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig, Daniel Walker, Jonathan Corbet, Mel Gorman, Chunsang Jeong, Michal Nazarewicz, Jesse Barker, Kyungmin Park, Ankita Garg, Andrew Morton, KAMEZAWA Hiroyuki On Tue, Jul 05, 2011 at 02:27:44PM +0200, Arnd Bergmann wrote: > It's also a preexisting problem as far as I can tell, and it needs > to be solved in __dma_alloc for both cases, dma_alloc_from_contiguous > and __alloc_system_pages as introduced in patch 7. Which is now resolved in linux-next, and has been through this cycle as previously discussed. It's taken some time because the guy who tested the patch for me said he'd review other platforms but never did, so I've just about given up waiting and stuffed it in ready for the 3.1 merge window irrespective of anything else. ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-05 12:30 ` Russell King - ARM Linux @ 2011-07-05 13:58 ` Arnd Bergmann 2011-07-08 17:25 ` Russell King - ARM Linux 0 siblings, 1 reply; 46+ messages in thread From: Arnd Bergmann @ 2011-07-05 13:58 UTC (permalink / raw) To: linux-arm-kernel Cc: Russell King - ARM Linux, Daniel Walker, Jonathan Corbet, Mel Gorman, Chunsang Jeong, Jesse Barker, KAMEZAWA Hiroyuki, linux-kernel, Michal Nazarewicz, linaro-mm-sig, linux-mm, Kyungmin Park, Ankita Garg, Andrew Morton, Marek Szyprowski, linux-media On Tuesday 05 July 2011, Russell King - ARM Linux wrote: > On Tue, Jul 05, 2011 at 02:27:44PM +0200, Arnd Bergmann wrote: > > It's also a preexisting problem as far as I can tell, and it needs > > to be solved in __dma_alloc for both cases, dma_alloc_from_contiguous > > and __alloc_system_pages as introduced in patch 7. > > Which is now resolved in linux-next, and has been through this cycle > as previously discussed. > > It's taken some time because the guy who tested the patch for me said > he'd review other platforms but never did, so I've just about given up > waiting and stuffed it in ready for the 3.1 merge window irrespective > of anything else. Ah, sorry I missed that patch on the mailing list, found it now in your for-next branch. If I'm reading your "ARM: DMA: steal memory for DMA coherent mappings" correctly, the idea is to have a per-platform compile-time amount of memory that is reserved purely for coherent allocations and taking out of the buddy allocator, right? As you say, this solves the problem for the non-CMA case, and does not apply to CMA because the entire point of CMA is not to remove the pages from the buddy allocator in order to preserve memory. So with your patch getting merged, patch 7/8 obviously has both a conflict and introduces a regression against the fix you did. Consequently that patch needs to be redone in a way that fits on top of your patch and avoids the double-mapping problem. What about the rest? As I mentioned in private, adding invasive features to core code is obviously not nice if it can be avoided, but my feeling is that we can no longer claim that there is no need for this with so much hardware relying on large contiguous memory ranges for DMA. The patches have come a long way since the first version, especially regarding the device driver interface and I think they are about as good as it gets in that regard. I do understand that without patch 7, there isn't a single architecture using the feature, which is somewhat silly, but I'm also convinced that other architectures will start using it, and that a solution for the double mapping in the ways I mentioned in my previous mail is going to happen. Probably not in 3.1 then, but we could put the patches into -mm anyway until we get there. Arnd ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-05 13:58 ` Arnd Bergmann @ 2011-07-08 17:25 ` Russell King - ARM Linux 2011-07-12 13:39 ` Arnd Bergmann 0 siblings, 1 reply; 46+ messages in thread From: Russell King - ARM Linux @ 2011-07-08 17:25 UTC (permalink / raw) To: Arnd Bergmann Cc: linux-arm-kernel, Daniel Walker, Jonathan Corbet, Mel Gorman, Chunsang Jeong, Jesse Barker, KAMEZAWA Hiroyuki, linux-kernel, Michal Nazarewicz, linaro-mm-sig, linux-mm, Kyungmin Park, Ankita Garg, Andrew Morton, Marek Szyprowski, linux-media On Tue, Jul 05, 2011 at 03:58:39PM +0200, Arnd Bergmann wrote: > Ah, sorry I missed that patch on the mailing list, found it now in > your for-next branch. I've been searching for this email to reply to for the last day or so... > If I'm reading your "ARM: DMA: steal memory for DMA coherent mappings" > correctly, the idea is to have a per-platform compile-time amount > of memory that is reserved purely for coherent allocations and > taking out of the buddy allocator, right? Yes, because every time I've looked at taking out memory mappings in the first level page tables, it's always been a major issue. We have a method where we can remove first level mappings on uniprocessor systems in the ioremap code just fine - we use that so that systems can setup section and supersection mappings. They can tear them down as well - and we update other tasks L1 page tables when they get switched in. This, however, doesn't work on SMP, because if you have a DMA allocation (which is permitted from IRQ context) you must have some way of removing the L1 page table entries from all CPUs TLBs and the page tables currently in use and any future page tables which those CPUs may switch to. The easy bit is "future page tables" - that can be done in the same way as the ioremap() code does with a generation number, checked when a new page table is switched in. The problem is the current CPUs, and as we know trying to call smp_call_function() with IRQs disabled is not permitted due to deadlock. So, in a SMP system, there is no safe way to remove L1 page table entries from IRQ context. That means if memory is mapped for the buddy allocators using L1 page table entries, then it is fixed for that application on a SMP system. However, that's not really what I wanted to find this email for. That is I'm dropping the "ARM: DMA: steal memory for DMA coherent mappings" patch for this merge window because - as I found out yesterday - it prevents the Assabet platform booting, and so would be a regression. Plus, I have a report of a regression with the streaming DMA API speculative prefetch fixes causing the IOP ADMA raid5 async offload stuff to explode - which may result in the streaming DMA API fixes being reverted (which will leave ARMv6+ vulnerable to data corruption.) As I have no time to work through the RAID5 code, async_tx code, and IOP ADMA code to get to the bottom of it (because of this flood of patches) I think a revert is looking likely - either that or I'll have to tell the bug reporter to go away, which really isn't on. It's on LKML if anyone's interested in trying to diagnose it, the "PROBLEM: ARM-dma-mapping-fix-for-speculative-prefetching cause OOPS" thread. ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-08 17:25 ` Russell King - ARM Linux @ 2011-07-12 13:39 ` Arnd Bergmann 0 siblings, 0 replies; 46+ messages in thread From: Arnd Bergmann @ 2011-07-12 13:39 UTC (permalink / raw) To: Russell King - ARM Linux Cc: linux-arm-kernel, Daniel Walker, Jonathan Corbet, Mel Gorman, Chunsang Jeong, Jesse Barker, KAMEZAWA Hiroyuki, linux-kernel, Michal Nazarewicz, linaro-mm-sig, linux-mm, Kyungmin Park, Ankita Garg, Andrew Morton, Marek Szyprowski, linux-media On Friday 08 July 2011, Russell King - ARM Linux wrote: > On Tue, Jul 05, 2011 at 03:58:39PM +0200, Arnd Bergmann wrote: > > > If I'm reading your "ARM: DMA: steal memory for DMA coherent mappings" > > correctly, the idea is to have a per-platform compile-time amount > > of memory that is reserved purely for coherent allocations and > > taking out of the buddy allocator, right? > > Yes, because every time I've looked at taking out memory mappings in > the first level page tables, it's always been a major issue. > > We have a method where we can remove first level mappings on > uniprocessor systems in the ioremap code just fine - we use that so > that systems can setup section and supersection mappings. They can > tear them down as well - and we update other tasks L1 page tables > when they get switched in. > > This, however, doesn't work on SMP, because if you have a DMA allocation > (which is permitted from IRQ context) you must have some way of removing > the L1 page table entries from all CPUs TLBs and the page tables currently > in use and any future page tables which those CPUs may switch to. Ah, interesting. So there is no tlb flush broadcast operation and it always goes through IPI? > So, in a SMP system, there is no safe way to remove L1 page table entries > from IRQ context. That means if memory is mapped for the buddy allocators > using L1 page table entries, then it is fixed for that application on a > SMP system. Ok. Can we limit GFP_ATOMIC to memory that doesn't need to be remapped then? I guess we can assume that there is no regression if we just skip the dma_alloc_contiguous step in dma_alloc_coherent for any atomic callers and immediately fall back to the regular allocator. Unfortunately, this still means we have to keep both methods. I was hoping that with CMA doing dynamic remapping there would be no need for keeping a significant number of pages reserved for this. Arnd ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-05 12:27 ` Arnd Bergmann 2011-07-05 12:30 ` Russell King - ARM Linux @ 2011-08-03 17:43 ` James Bottomley 2011-09-26 12:06 ` Marek Szyprowski 2011-09-26 13:00 ` Russell King - ARM Linux 1 sibling, 2 replies; 46+ messages in thread From: James Bottomley @ 2011-08-03 17:43 UTC (permalink / raw) To: Arnd Bergmann Cc: Russell King - ARM Linux, Marek Szyprowski, linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig, Daniel Walker, Jonathan Corbet, Mel Gorman, Chunsang Jeong, Michal Nazarewicz, Jesse Barker, Kyungmin Park, Ankita Garg, Andrew Morton, KAMEZAWA Hiroyuki, ksummit-2011-discuss [cc to ks-discuss added, since this may be a relevant topic] On Tue, 2011-07-05 at 14:27 +0200, Arnd Bergmann wrote: > On Tuesday 05 July 2011, Russell King - ARM Linux wrote: > > On Tue, Jul 05, 2011 at 09:41:48AM +0200, Marek Szyprowski wrote: > > > The Contiguous Memory Allocator is a set of helper functions for DMA > > > mapping framework that improves allocations of contiguous memory chunks. > > > > > > CMA grabs memory on system boot, marks it with CMA_MIGRATE_TYPE and > > > gives back to the system. Kernel is allowed to allocate movable pages > > > within CMA's managed memory so that it can be used for example for page > > > cache when DMA mapping do not use it. On dma_alloc_from_contiguous() > > > request such pages are migrated out of CMA area to free required > > > contiguous block and fulfill the request. This allows to allocate large > > > contiguous chunks of memory at any time assuming that there is enough > > > free memory available in the system. > > > > > > This code is heavily based on earlier works by Michal Nazarewicz. > > > > And how are you addressing the technical concerns about aliasing of > > cache attributes which I keep bringing up with this and you keep > > ignoring and telling me that I'm standing in your way. Just to chime in here, parisc has an identical issue. If the CPU ever sees an alias with different attributes for the same page, it will HPMC the box (that's basically the bios will kill the system as being architecturally inconsistent), so an architecture neutral solution on this point is essential to us as well. > This is of course an important issue, and it's the one item listed as > TODO in the introductory mail that sent. > > It's also a preexisting problem as far as I can tell, and it needs > to be solved in __dma_alloc for both cases, dma_alloc_from_contiguous > and __alloc_system_pages as introduced in patch 7. > > We've discussed this back and forth, and it always comes down to > one of two ugly solutions: > > 1. Put all of the MIGRATE_CMA and pages into highmem and change > __alloc_system_pages so it also allocates only from highmem pages. > The consequences of this are that we always need to build kernels > with highmem enabled and that we have less lowmem on systems that > are already small, both of which can be fairly expensive unless > you have lots of highmem already. So this would require that systems using the API have a highmem? (parisc doesn't today). > 2. Add logic to unmap pages from the linear mapping, which is > very expensive because it forces the use of small pages in the > linear mapping (or in parts of it), and possibly means walking > all page tables to remove the PTEs on alloc and put them back > in on free. > > I believe that Chunsang Jeong from Linaro is planning to > implement both variants and post them for review, so we can > decide which one to merge, or even to merge both and make > it a configuration option. See also > https://blueprints.launchpad.net/linaro-mm-sig/+spec/engr-mm-dma-mapping-2011.07 > > I don't think we need to make merging the CMA patches depending on > the other patches, it's clear that both need to be solved, and > they are independent enough. I assume from the above that ARM has a hardware page walker? The way I'd fix this on parisc, because we have a software based TLB, is to rely on the fact that a page may only be used either for DMA or for Page Cache, so the aliases should never be interleaved. Since you know the point at which the page flips from DMA to Cache (and vice versa), I'd purge the TLB entry and flush the page at that point and rely on the usage guarantees to ensure that the alias TLB entry doesn't reappear. This isn't inexpensive but the majority of the cost is the cache flush which is a requirement to clean the aliases anyway (a TLB entry purge is pretty cheap). Would this work for the ARM hardware walker as well? It would require you to have a TLB entry purge instruction as well as some architectural guarantees about not speculating the TLB. James ^ permalink raw reply [flat|nested] 46+ messages in thread
* RE: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-08-03 17:43 ` James Bottomley @ 2011-09-26 12:06 ` Marek Szyprowski 2011-09-26 13:00 ` Russell King - ARM Linux 1 sibling, 0 replies; 46+ messages in thread From: Marek Szyprowski @ 2011-09-26 12:06 UTC (permalink / raw) To: 'James Bottomley', 'Arnd Bergmann' Cc: 'Russell King - ARM Linux', linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig, 'Daniel Walker', 'Jonathan Corbet', 'Mel Gorman', 'Chunsang Jeong', 'Michal Nazarewicz', 'Jesse Barker', 'Kyungmin Park', 'Ankita Garg', 'Andrew Morton', 'KAMEZAWA Hiroyuki', ksummit-2011-discuss Hello, I'm sorry for the late reply. I must have missed this mail... On Wednesday, August 03, 2011 7:44 PM James Bottomley wrote: > [cc to ks-discuss added, since this may be a relevant topic] > > On Tue, 2011-07-05 at 14:27 +0200, Arnd Bergmann wrote: > > On Tuesday 05 July 2011, Russell King - ARM Linux wrote: > > > On Tue, Jul 05, 2011 at 09:41:48AM +0200, Marek Szyprowski wrote: > > > > The Contiguous Memory Allocator is a set of helper functions for DMA > > > > mapping framework that improves allocations of contiguous memory chunks. > > > > > > > > CMA grabs memory on system boot, marks it with CMA_MIGRATE_TYPE and > > > > gives back to the system. Kernel is allowed to allocate movable pages > > > > within CMA's managed memory so that it can be used for example for page > > > > cache when DMA mapping do not use it. On dma_alloc_from_contiguous() > > > > request such pages are migrated out of CMA area to free required > > > > contiguous block and fulfill the request. This allows to allocate large > > > > contiguous chunks of memory at any time assuming that there is enough > > > > free memory available in the system. > > > > > > > > This code is heavily based on earlier works by Michal Nazarewicz. > > > > > > And how are you addressing the technical concerns about aliasing of > > > cache attributes which I keep bringing up with this and you keep > > > ignoring and telling me that I'm standing in your way. > > Just to chime in here, parisc has an identical issue. If the CPU ever > sees an alias with different attributes for the same page, it will HPMC > the box (that's basically the bios will kill the system as being > architecturally inconsistent), so an architecture neutral solution on > this point is essential to us as well. > > > This is of course an important issue, and it's the one item listed as > > TODO in the introductory mail that sent. > > > > It's also a preexisting problem as far as I can tell, and it needs > > to be solved in __dma_alloc for both cases, dma_alloc_from_contiguous > > and __alloc_system_pages as introduced in patch 7. > > > > We've discussed this back and forth, and it always comes down to > > one of two ugly solutions: > > > > 1. Put all of the MIGRATE_CMA and pages into highmem and change > > __alloc_system_pages so it also allocates only from highmem pages. > > The consequences of this are that we always need to build kernels > > with highmem enabled and that we have less lowmem on systems that > > are already small, both of which can be fairly expensive unless > > you have lots of highmem already. > > So this would require that systems using the API have a highmem? (parisc > doesn't today). Yes, such solution will require highmem. It will introduce the highmem issues to systems that typically don't use highmem, that's why I searched for other solutions. > > 2. Add logic to unmap pages from the linear mapping, which is > > very expensive because it forces the use of small pages in the > > linear mapping (or in parts of it), and possibly means walking > > all page tables to remove the PTEs on alloc and put them back > > in on free. > > > > I believe that Chunsang Jeong from Linaro is planning to > > implement both variants and post them for review, so we can > > decide which one to merge, or even to merge both and make > > it a configuration option. See also > > https://blueprints.launchpad.net/linaro-mm-sig/+spec/engr-mm-dma-mapping-2011.07 > > > > I don't think we need to make merging the CMA patches depending on > > the other patches, it's clear that both need to be solved, and > > they are independent enough. > > I assume from the above that ARM has a hardware page walker? Right. > The way I'd fix this on parisc, because we have a software based TLB, is > to rely on the fact that a page may only be used either for DMA or for > Page Cache, so the aliases should never be interleaved. Since you know > the point at which the page flips from DMA to Cache (and vice versa), > I'd purge the TLB entry and flush the page at that point and rely on the > usage guarantees to ensure that the alias TLB entry doesn't reappear. > This isn't inexpensive but the majority of the cost is the cache flush > which is a requirement to clean the aliases anyway (a TLB entry purge is > pretty cheap). > > Would this work for the ARM hardware walker as well? It would require > you to have a TLB entry purge instruction as well as some architectural > guarantees about not speculating the TLB. The main problem with ARM linear mapping is the fact that it is created using 2MiB sections, so entries for kernel linear mapping fits entirely in first lever of process page table. This implies that direct changing this linear mapping is not easy task and must be performed for all tasks in the system. In my CMA v12+ patches I decided to use simpler way of solving this issue. I rely on the fact that DMA memory is allocated only from CMA regions, so during early boot I change the kernel linear mappings for these regions. Instead of 2MiB sections, I use regular 4KiB pages which create 2 level of page tables. Second level of page table for these regions can be easily shared for all processes in the system. This way I can easily update cache attributes for any single 4KiB page that is used for DMA and avoid any aliasing at all. The only drawback of this method is larger TLB pressure what might result in some slowdown during heavy IO if pages with 4KiB linear mapping are used. However with my hardware has only slow io (with eMMC I get only about 30MiB/s) so I cannot notice any impact of the mapping method on the io speed. Best regards -- Marek Szyprowski Samsung Poland R&D Center ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-08-03 17:43 ` James Bottomley 2011-09-26 12:06 ` Marek Szyprowski @ 2011-09-26 13:00 ` Russell King - ARM Linux 1 sibling, 0 replies; 46+ messages in thread From: Russell King - ARM Linux @ 2011-09-26 13:00 UTC (permalink / raw) To: James Bottomley Cc: Arnd Bergmann, Daniel Walker, Jonathan Corbet, Mel Gorman, Chunsang Jeong, Jesse Barker, KAMEZAWA Hiroyuki, linux-kernel, Michal Nazarewicz, linaro-mm-sig, linux-mm, Kyungmin Park, Ankita Garg, Andrew Morton, Marek Szyprowski, ksummit-2011-discuss, linux-arm-kernel, linux-media On Wed, Aug 03, 2011 at 12:43:50PM -0500, James Bottomley wrote: > I assume from the above that ARM has a hardware page walker? Correct, and speculative prefetch (which isn't prevented by not having TLB entries), so you can't keep entries out of the TLB. If it's in the page tables it can end up in the TLB. The problem is that we could end up with conflicting attributes available to the hardware for the same physical page, and it is _completely_ undefined how hardware behaves with that (except that it does not halt - and there's no exception path for the condition because there's no detection of the problem case.) So, if you had one mapping which was fully cacheable and another mapping which wasn't, you can flush the TLB all you like - it could be possible that you still up with an access through the non-cacheable mapping being cached (either hitting speculatively prefetched cache lines via the cacheable mapping, or the cacheable attributes being applied to the non-cacheable mapping - or conversely uncacheable attributes applied to the cacheable mapping.) Essentially, the condition is labelled 'unpredictable' in the TRMs, which basically means that not even observed behaviour can be relied upon, because there may be cases where the observed behaviour fails. ^ permalink raw reply [flat|nested] 46+ messages in thread
* RE: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-05 11:33 ` Russell King - ARM Linux 2011-07-05 12:27 ` Arnd Bergmann @ 2011-07-06 13:58 ` Marek Szyprowski 2011-07-06 14:09 ` Arnd Bergmann 1 sibling, 1 reply; 46+ messages in thread From: Marek Szyprowski @ 2011-07-06 13:58 UTC (permalink / raw) To: 'Russell King - ARM Linux' Cc: linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig, 'Daniel Walker', 'Arnd Bergmann', 'Jonathan Corbet', 'Mel Gorman', 'Chunsang Jeong', 'Michal Nazarewicz', 'Jesse Barker', 'Kyungmin Park', 'Ankita Garg', 'Andrew Morton', 'KAMEZAWA Hiroyuki', Marek Szyprowski Hello, On Tuesday, July 05, 2011 1:34 PM Russell King - ARM Linux wrote: > On Tue, Jul 05, 2011 at 09:41:48AM +0200, Marek Szyprowski wrote: > > The Contiguous Memory Allocator is a set of helper functions for DMA > > mapping framework that improves allocations of contiguous memory chunks. > > > > CMA grabs memory on system boot, marks it with CMA_MIGRATE_TYPE and > > gives back to the system. Kernel is allowed to allocate movable pages > > within CMA's managed memory so that it can be used for example for page > > cache when DMA mapping do not use it. On dma_alloc_from_contiguous() > > request such pages are migrated out of CMA area to free required > > contiguous block and fulfill the request. This allows to allocate large > > contiguous chunks of memory at any time assuming that there is enough > > free memory available in the system. > > > > This code is heavily based on earlier works by Michal Nazarewicz. > > And how are you addressing the technical concerns about aliasing of > cache attributes which I keep bringing up with this and you keep > ignoring and telling me that I'm standing in your way. I'm perfectly aware of the issues with aliasing of cache attributes. My idea is to change low memory linear mapping for all CMA areas on boot time to use 2 level page tables (4KiB mappings instead of super-section mappings). This way the page properties for a single page in CMA area can be changed/updated at any time to match required coherent/writecombine attributes. Linear mapping can be even removed completely if we want to create the it elsewhere in the address space. The only problem that might need to be resolved is GFP_ATOMIC allocation (updating page properties probably requires some locking), but it can be served from a special area which is created on boot without low-memory mapping at all. None sane driver will call dma_alloc_coherent(GFP_ATOMIC) for large buffers anyway. CMA limits the memory area from which coherent pages are being taken quite well, so the change in the linear mapping method should have no significant impact on the system performance. I didn't implement such solution yet, because it is really hard to handle all issues at the same time and creating the allocator was just a first step. Best regards -- Marek Szyprowski Samsung Poland R&D Center ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-06 13:58 ` Marek Szyprowski @ 2011-07-06 14:09 ` Arnd Bergmann 2011-07-06 14:23 ` Russell King - ARM Linux 2011-07-06 14:56 ` Marek Szyprowski 0 siblings, 2 replies; 46+ messages in thread From: Arnd Bergmann @ 2011-07-06 14:09 UTC (permalink / raw) To: Marek Szyprowski Cc: 'Russell King - ARM Linux', linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig, 'Daniel Walker', 'Jonathan Corbet', 'Mel Gorman', 'Chunsang Jeong', 'Michal Nazarewicz', 'Jesse Barker', 'Kyungmin Park', 'Ankita Garg', 'Andrew Morton', 'KAMEZAWA Hiroyuki' On Wednesday 06 July 2011, Marek Szyprowski wrote: > The only problem that might need to be resolved is GFP_ATOMIC allocation > (updating page properties probably requires some locking), but it can be > served from a special area which is created on boot without low-memory > mapping at all. None sane driver will call dma_alloc_coherent(GFP_ATOMIC) > for large buffers anyway. Would it be easier to start with a version that only allocated from memory without a low-memory mapping at first? This would be similar to the approach that Russell's fix for the regular dma_alloc_coherent has taken, except that you need to also allow the memory to be used as highmem user pages. Maybe you can simply adapt the default location of the contiguous memory are like this: - make CONFIG_CMA depend on CONFIG_HIGHMEM on ARM, at compile time - if ZONE_HIGHMEM exist during boot, put the CMA area in there - otherwise, put the CMA area at the top end of lowmem, and change the zone sizes so ZONE_HIGHMEM stretches over all of the CMA memory. Arnd ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-06 14:09 ` Arnd Bergmann @ 2011-07-06 14:23 ` Russell King - ARM Linux 2011-07-06 14:51 ` Arnd Bergmann 2011-07-06 14:56 ` Marek Szyprowski 1 sibling, 1 reply; 46+ messages in thread From: Russell King - ARM Linux @ 2011-07-06 14:23 UTC (permalink / raw) To: Arnd Bergmann Cc: Marek Szyprowski, linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig, 'Daniel Walker', 'Jonathan Corbet', 'Mel Gorman', 'Chunsang Jeong', 'Michal Nazarewicz', 'Jesse Barker', 'Kyungmin Park', 'Ankita Garg', 'Andrew Morton', 'KAMEZAWA Hiroyuki' On Wed, Jul 06, 2011 at 04:09:29PM +0200, Arnd Bergmann wrote: > Maybe you can simply adapt the default location of the contiguous memory > are like this: > - make CONFIG_CMA depend on CONFIG_HIGHMEM on ARM, at compile time > - if ZONE_HIGHMEM exist during boot, put the CMA area in there > - otherwise, put the CMA area at the top end of lowmem, and change > the zone sizes so ZONE_HIGHMEM stretches over all of the CMA memory. One of the requirements of the allocator is that the returned memory should be zero'd (because it can be exposed to userspace via ALSA and frame buffers.) Zeroing the memory from all the contexts which dma_alloc_coherent is called from is a trivial matter if its in lowmem, but highmem is harder. Another issue is that when a platform has restricted DMA regions, they typically don't fall into the highmem zone. As the dmabounce code allocates from the DMA coherent allocator to provide it with guaranteed DMA-able memory, that would be rather inconvenient. ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-06 14:23 ` Russell King - ARM Linux @ 2011-07-06 14:51 ` Arnd Bergmann 2011-07-06 15:48 ` Russell King - ARM Linux 0 siblings, 1 reply; 46+ messages in thread From: Arnd Bergmann @ 2011-07-06 14:51 UTC (permalink / raw) To: linux-arm-kernel Cc: Russell King - ARM Linux, 'Daniel Walker', 'Jonathan Corbet', 'Mel Gorman', 'Chunsang Jeong', 'Jesse Barker', 'KAMEZAWA Hiroyuki', linux-kernel, 'Michal Nazarewicz', linaro-mm-sig, linux-mm, 'Kyungmin Park', 'Ankita Garg', 'Andrew Morton', Marek Szyprowski, linux-media On Wednesday 06 July 2011, Russell King - ARM Linux wrote: > On Wed, Jul 06, 2011 at 04:09:29PM +0200, Arnd Bergmann wrote: > > Maybe you can simply adapt the default location of the contiguous memory > > are like this: > > - make CONFIG_CMA depend on CONFIG_HIGHMEM on ARM, at compile time > > - if ZONE_HIGHMEM exist during boot, put the CMA area in there > > - otherwise, put the CMA area at the top end of lowmem, and change > > the zone sizes so ZONE_HIGHMEM stretches over all of the CMA memory. > > One of the requirements of the allocator is that the returned memory > should be zero'd (because it can be exposed to userspace via ALSA > and frame buffers.) > > Zeroing the memory from all the contexts which dma_alloc_coherent > is called from is a trivial matter if its in lowmem, but highmem is > harder. I don't see how. The pages get allocated from an unmapped area or memory, mapped into the kernel address space as uncached or wc and then cleared. This should be the same for lowmem or highmem pages. What am I missing? > Another issue is that when a platform has restricted DMA regions, > they typically don't fall into the highmem zone. As the dmabounce > code allocates from the DMA coherent allocator to provide it with > guaranteed DMA-able memory, that would be rather inconvenient. True. The dmabounce code would consequently have to allocate the memory through an internal function that avoids the contiguous allocation area and goes straight to ZONE_DMA memory as it does today. Arnd ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-06 14:51 ` Arnd Bergmann @ 2011-07-06 15:48 ` Russell King - ARM Linux 2011-07-06 16:05 ` Christoph Lameter 2011-07-06 16:31 ` Arnd Bergmann 0 siblings, 2 replies; 46+ messages in thread From: Russell King - ARM Linux @ 2011-07-06 15:48 UTC (permalink / raw) To: Arnd Bergmann Cc: linux-arm-kernel, 'Daniel Walker', 'Jonathan Corbet', 'Mel Gorman', 'Chunsang Jeong', 'Jesse Barker', 'KAMEZAWA Hiroyuki', linux-kernel, 'Michal Nazarewicz', linaro-mm-sig, linux-mm, 'Kyungmin Park', 'Ankita Garg', 'Andrew Morton', Marek Szyprowski, linux-media On Wed, Jul 06, 2011 at 04:51:49PM +0200, Arnd Bergmann wrote: > On Wednesday 06 July 2011, Russell King - ARM Linux wrote: > > On Wed, Jul 06, 2011 at 04:09:29PM +0200, Arnd Bergmann wrote: > > > Maybe you can simply adapt the default location of the contiguous memory > > > are like this: > > > - make CONFIG_CMA depend on CONFIG_HIGHMEM on ARM, at compile time > > > - if ZONE_HIGHMEM exist during boot, put the CMA area in there > > > - otherwise, put the CMA area at the top end of lowmem, and change > > > the zone sizes so ZONE_HIGHMEM stretches over all of the CMA memory. > > > > One of the requirements of the allocator is that the returned memory > > should be zero'd (because it can be exposed to userspace via ALSA > > and frame buffers.) > > > > Zeroing the memory from all the contexts which dma_alloc_coherent > > is called from is a trivial matter if its in lowmem, but highmem is > > harder. > > I don't see how. The pages get allocated from an unmapped area > or memory, mapped into the kernel address space as uncached or wc > and then cleared. This should be the same for lowmem or highmem > pages. You don't want to clear them via their uncached or WC mapping, but via their cached mapping _before_ they get their alternative mapping, and flush any cached out of that mapping - both L1 and L2 caches. For lowmem pages, that's easy. For highmem pages, they need to be individually kmap'd to zero them etc. (alloc_pages() warns on GFP_HIGHMEM + GFP_ZERO from atomic contexts - and dma_alloc_coherent must be callable from such contexts.) That may be easier now that we don't have the explicit indicies for kmap_atomics, but at that time it wasn't easily possible. > > Another issue is that when a platform has restricted DMA regions, > > they typically don't fall into the highmem zone. As the dmabounce > > code allocates from the DMA coherent allocator to provide it with > > guaranteed DMA-able memory, that would be rather inconvenient. > > True. The dmabounce code would consequently have to allocate > the memory through an internal function that avoids the > contiguous allocation area and goes straight to ZONE_DMA memory > as it does today. CMA's whole purpose for existing is to provide _dma-able_ contiguous memory for things like cameras and such like found on crippled non- scatter-gather hardware. If that memory is not DMA-able what's the point? ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-06 15:48 ` Russell King - ARM Linux @ 2011-07-06 16:05 ` Christoph Lameter 2011-07-06 16:09 ` Michal Nazarewicz 2011-07-06 17:02 ` Russell King - ARM Linux 2011-07-06 16:31 ` Arnd Bergmann 1 sibling, 2 replies; 46+ messages in thread From: Christoph Lameter @ 2011-07-06 16:05 UTC (permalink / raw) To: Russell King - ARM Linux Cc: Arnd Bergmann, linux-arm-kernel, 'Daniel Walker', 'Jonathan Corbet', 'Mel Gorman', 'Chunsang Jeong', 'Jesse Barker', 'KAMEZAWA Hiroyuki', linux-kernel, 'Michal Nazarewicz', linaro-mm-sig, linux-mm, 'Kyungmin Park', 'Ankita Garg', 'Andrew Morton', Marek Szyprowski, linux-media On Wed, 6 Jul 2011, Russell King - ARM Linux wrote: > > > they typically don't fall into the highmem zone. As the dmabounce > > > code allocates from the DMA coherent allocator to provide it with > > > guaranteed DMA-able memory, that would be rather inconvenient. > > > > True. The dmabounce code would consequently have to allocate > > the memory through an internal function that avoids the > > contiguous allocation area and goes straight to ZONE_DMA memory > > as it does today. > > CMA's whole purpose for existing is to provide _dma-able_ contiguous > memory for things like cameras and such like found on crippled non- > scatter-gather hardware. If that memory is not DMA-able what's the > point? ZONE_DMA is a zone for memory of legacy (crippled) devices that cannot DMA into all of memory (and so is ZONE_DMA32). Memory from ZONE_NORMAL can be used for DMA as well and a fully capable device would be expected to handle any memory in the system for DMA transfers. "guaranteed" dmaable memory? DMA abilities are device specific. Well maybe you can call ZONE_DMA memory to be guaranteed if you guarantee that any device must at mininum be able to perform DMA into ZONE_DMA memory. But there may not be much of that memory around so you would want to limit the use of that scarce resource. ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-06 16:05 ` Christoph Lameter @ 2011-07-06 16:09 ` Michal Nazarewicz 2011-07-06 16:19 ` Christoph Lameter 2011-07-06 17:02 ` Russell King - ARM Linux 1 sibling, 1 reply; 46+ messages in thread From: Michal Nazarewicz @ 2011-07-06 16:09 UTC (permalink / raw) To: Russell King - ARM Linux, Christoph Lameter Cc: Arnd Bergmann, linux-arm-kernel, 'Daniel Walker', 'Jonathan Corbet', 'Mel Gorman', 'Chunsang Jeong', 'Jesse Barker', 'KAMEZAWA Hiroyuki', linux-kernel, linaro-mm-sig, linux-mm, 'Kyungmin Park', 'Ankita Garg', 'Andrew Morton', Marek Szyprowski, linux-media On Wed, 06 Jul 2011 18:05:00 +0200, Christoph Lameter <cl@linux.com> wrote: > ZONE_DMA is a zone for memory of legacy (crippled) devices that cannot > DMA into all of memory (and so is ZONE_DMA32). Memory from ZONE_NORMAL > can be used for DMA as well and a fully capable device would be expected > to handle any memory in the system for DMA transfers. > > "guaranteed" dmaable memory? DMA abilities are device specific. Well > maybe you can call ZONE_DMA memory to be guaranteed if you guarantee > that any device must at mininum be able to perform DMA into ZONE_DMA > memory. But there may not be much of that memory around so you would > want to limit the use of that scarce resource. As pointed in Marek's other mail, this reasoning is not helping in any way. In case of video codec on various Samsung devices (and from some other threads this is not limited to Samsung), the codec needs separate buffers in separate memory banks. -- Best regards, _ _ .o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o ..o | Computer Science, Michal "mina86" Nazarewicz (o o) ooo +-----<email/xmpp: mnazarewicz@google.com>-----ooO--(_)--Ooo-- ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-06 16:09 ` Michal Nazarewicz @ 2011-07-06 16:19 ` Christoph Lameter 2011-07-06 17:15 ` Russell King - ARM Linux 0 siblings, 1 reply; 46+ messages in thread From: Christoph Lameter @ 2011-07-06 16:19 UTC (permalink / raw) To: Michal Nazarewicz Cc: Russell King - ARM Linux, Arnd Bergmann, linux-arm-kernel, 'Daniel Walker', 'Jonathan Corbet', 'Mel Gorman', 'Chunsang Jeong', 'Jesse Barker', 'KAMEZAWA Hiroyuki', linux-kernel, linaro-mm-sig, linux-mm, 'Kyungmin Park', 'Ankita Garg', 'Andrew Morton', Marek Szyprowski, linux-media, Andi Kleen On Wed, 6 Jul 2011, Michal Nazarewicz wrote: > On Wed, 06 Jul 2011 18:05:00 +0200, Christoph Lameter <cl@linux.com> wrote: > > ZONE_DMA is a zone for memory of legacy (crippled) devices that cannot DMA > > into all of memory (and so is ZONE_DMA32). Memory from ZONE_NORMAL > > can be used for DMA as well and a fully capable device would be expected > > to handle any memory in the system for DMA transfers. > > > > "guaranteed" dmaable memory? DMA abilities are device specific. Well maybe > > you can call ZONE_DMA memory to be guaranteed if you guarantee > > that any device must at mininum be able to perform DMA into ZONE_DMA > > memory. But there may not be much of that memory around so you would > > want to limit the use of that scarce resource. > > As pointed in Marek's other mail, this reasoning is not helping in any > way. In case of video codec on various Samsung devices (and from some > other threads this is not limited to Samsung), the codec needs separate > buffers in separate memory banks. What I described is the basic memory architecture of Linux. I am not that familiar with ARM and the issue discussed here. Only got involved because ZONE_DMA was mentioned. The nature of ZONE_DMA is often misunderstood. The allocation of the memory banks for the Samsung devices has to fit somehow into one of these zones. Its probably best to put the memory banks into ZONE_NORMAL and not have any dependency on ZONE_DMA at all. ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-06 16:19 ` Christoph Lameter @ 2011-07-06 17:15 ` Russell King - ARM Linux 2011-07-06 19:03 ` Christoph Lameter 0 siblings, 1 reply; 46+ messages in thread From: Russell King - ARM Linux @ 2011-07-06 17:15 UTC (permalink / raw) To: Christoph Lameter Cc: Michal Nazarewicz, Arnd Bergmann, linux-arm-kernel, 'Daniel Walker', 'Jonathan Corbet', 'Mel Gorman', 'Chunsang Jeong', 'Jesse Barker', 'KAMEZAWA Hiroyuki', linux-kernel, linaro-mm-sig, linux-mm, 'Kyungmin Park', 'Ankita Garg', 'Andrew Morton', Marek Szyprowski, linux-media, Andi Kleen On Wed, Jul 06, 2011 at 11:19:00AM -0500, Christoph Lameter wrote: > What I described is the basic memory architecture of Linux. I am not that > familiar with ARM and the issue discussed here. Only got involved because > ZONE_DMA was mentioned. The nature of ZONE_DMA is often misunderstood. > > The allocation of the memory banks for the Samsung devices has to fit > somehow into one of these zones. Its probably best to put the memory banks > into ZONE_NORMAL and not have any dependency on ZONE_DMA at all. Let me teach you about the ARM memory management on Linux. Firstly, lets go over the structure of zones in Linux. There are three zones - ZONE_DMA, ZONE_NORMAL and ZONE_HIGHMEM. These zones are filled in that order. So, ZONE_DMA starts at zero. Following on from ZONE_DMA is ZONE_NORMAL memory, and lastly ZONE_HIGHMEM. At boot, we pass all memory over to the kernel as follows: 1. If there is no DMA zone, then we pass all low memory over as ZONE_NORMAL. 2. If there is a DMA zone, by default we pass all low memory as ZONE_DMA. This is required so drivers which use GFP_DMA can work. Platforms with restricted DMA requirements can modify that layout to move memory from ZONE_DMA into ZONE_NORMAL, thereby restricting the upper address which the kernel allocators will give for GFP_DMA allocations. 3. In either case, any high memory as ZONE_HIGHMEM if configured (or memory is truncated if not.) So, when we have (eg) a platform where only the _even_ MBs of memory are DMA-able, we have a 1MB DMA zone at the beginning of system memory, and everything else in ZONE_NORMAL. This means GFP_DMA will return either memory from the first 1MB or fail if it can't. This is the behaviour we desire. Normal allocations will come from ZONE_NORMAL _first_ and then try ZONE_DMA if there's no other alternative. This is the same desired behaviour as x86. So, ARM is no different from x86, with the exception that the 16MB DMA zone due to ISA ends up being different sizes on ARM depending on our restrictions. ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-06 17:15 ` Russell King - ARM Linux @ 2011-07-06 19:03 ` Christoph Lameter 0 siblings, 0 replies; 46+ messages in thread From: Christoph Lameter @ 2011-07-06 19:03 UTC (permalink / raw) To: Russell King - ARM Linux Cc: Michal Nazarewicz, Arnd Bergmann, linux-arm-kernel, 'Daniel Walker', 'Jonathan Corbet', 'Mel Gorman', 'Chunsang Jeong', 'Jesse Barker', 'KAMEZAWA Hiroyuki', linux-kernel, linaro-mm-sig, linux-mm, 'Kyungmin Park', 'Ankita Garg', 'Andrew Morton', Marek Szyprowski, linux-media, Andi Kleen On Wed, 6 Jul 2011, Russell King - ARM Linux wrote: > So, ARM is no different from x86, with the exception that the 16MB DMA > zone due to ISA ends up being different sizes on ARM depending on our > restrictions. Sounds good. Thank you. ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-06 16:05 ` Christoph Lameter 2011-07-06 16:09 ` Michal Nazarewicz @ 2011-07-06 17:02 ` Russell King - ARM Linux 1 sibling, 0 replies; 46+ messages in thread From: Russell King - ARM Linux @ 2011-07-06 17:02 UTC (permalink / raw) To: Christoph Lameter Cc: Arnd Bergmann, linux-arm-kernel, 'Daniel Walker', 'Jonathan Corbet', 'Mel Gorman', 'Chunsang Jeong', 'Jesse Barker', 'KAMEZAWA Hiroyuki', linux-kernel, 'Michal Nazarewicz', linaro-mm-sig, linux-mm, 'Kyungmin Park', 'Ankita Garg', 'Andrew Morton', Marek Szyprowski, linux-media On Wed, Jul 06, 2011 at 11:05:00AM -0500, Christoph Lameter wrote: > On Wed, 6 Jul 2011, Russell King - ARM Linux wrote: > > > > > they typically don't fall into the highmem zone. As the dmabounce > > > > code allocates from the DMA coherent allocator to provide it with > > > > guaranteed DMA-able memory, that would be rather inconvenient. > > > > > > True. The dmabounce code would consequently have to allocate > > > the memory through an internal function that avoids the > > > contiguous allocation area and goes straight to ZONE_DMA memory > > > as it does today. > > > > CMA's whole purpose for existing is to provide _dma-able_ contiguous > > memory for things like cameras and such like found on crippled non- > > scatter-gather hardware. If that memory is not DMA-able what's the > > point? > > ZONE_DMA is a zone for memory of legacy (crippled) devices that cannot DMA > into all of memory (and so is ZONE_DMA32). Memory from ZONE_NORMAL can be > used for DMA as well and a fully capable device would be expected to > handle any memory in the system for DMA transfers. > > "guaranteed" dmaable memory? DMA abilities are device specific. Well maybe > you can call ZONE_DMA memory to be guaranteed if you guarantee that any > device must at mininum be able to perform DMA into ZONE_DMA memory. But > there may not be much of that memory around so you would want to limit > the use of that scarce resource. Precisely, which is what ZONE_DMA is all about. I *have* been a Linux kernel hacker for the last 18 years and do know these things, especially as ARM has had various issues with DMA memory limitations over those years - and have successfully had platforms working reliably given that and ZONE_DMA. ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-06 15:48 ` Russell King - ARM Linux 2011-07-06 16:05 ` Christoph Lameter @ 2011-07-06 16:31 ` Arnd Bergmann 2011-07-06 19:10 ` Nicolas Pitre 1 sibling, 1 reply; 46+ messages in thread From: Arnd Bergmann @ 2011-07-06 16:31 UTC (permalink / raw) To: Russell King - ARM Linux Cc: linux-arm-kernel, 'Daniel Walker', 'Jonathan Corbet', 'Mel Gorman', 'Chunsang Jeong', 'Jesse Barker', 'KAMEZAWA Hiroyuki', linux-kernel, 'Michal Nazarewicz', linaro-mm-sig, linux-mm, 'Kyungmin Park', 'Ankita Garg', 'Andrew Morton', Marek Szyprowski, linux-media On Wednesday 06 July 2011, Russell King - ARM Linux wrote: > On Wed, Jul 06, 2011 at 04:51:49PM +0200, Arnd Bergmann wrote: > > On Wednesday 06 July 2011, Russell King - ARM Linux wrote: > > > > I don't see how. The pages get allocated from an unmapped area > > or memory, mapped into the kernel address space as uncached or wc > > and then cleared. This should be the same for lowmem or highmem > > pages. > > You don't want to clear them via their uncached or WC mapping, but via > their cached mapping _before_ they get their alternative mapping, and > flush any cached out of that mapping - both L1 and L2 caches. But there can't be any other mapping, which is the whole point of the exercise to use highmem. Quoting from the new dma_alloc_area() function: c = arm_vmregion_alloc(&area->vm, align, size, gfp & ~(__GFP_DMA | __GFP_HIGHMEM)); if (!c) return NULL; memset((void *)c->vm_start, 0, size); area->vm here points to an uncached location, which means that we already zero the data through the uncached mapping. I don't see how it's getting worse than it is already. > > > Another issue is that when a platform has restricted DMA regions, > > > they typically don't fall into the highmem zone. As the dmabounce > > > code allocates from the DMA coherent allocator to provide it with > > > guaranteed DMA-able memory, that would be rather inconvenient. > > > > True. The dmabounce code would consequently have to allocate > > the memory through an internal function that avoids the > > contiguous allocation area and goes straight to ZONE_DMA memory > > as it does today. > > CMA's whole purpose for existing is to provide _dma-able_ contiguous > memory for things like cameras and such like found on crippled non- > scatter-gather hardware. If that memory is not DMA-able what's the > point? I mean not any ZONE_DMA memory, but the memory backing coherent_areas[], which is by definition DMA-able from any device and is what is currently being used for the purpose. Arnd ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-06 16:31 ` Arnd Bergmann @ 2011-07-06 19:10 ` Nicolas Pitre 0 siblings, 0 replies; 46+ messages in thread From: Nicolas Pitre @ 2011-07-06 19:10 UTC (permalink / raw) To: Arnd Bergmann Cc: Russell King - ARM Linux, linux-arm-kernel, 'Daniel Walker', 'Jonathan Corbet', 'Mel Gorman', 'Chunsang Jeong', 'Jesse Barker', 'KAMEZAWA Hiroyuki', lkml, 'Michal Nazarewicz', linaro-mm-sig, linux-mm, 'Kyungmin Park', 'Ankita Garg', 'Andrew Morton', Marek Szyprowski, linux-media On Wed, 6 Jul 2011, Arnd Bergmann wrote: > On Wednesday 06 July 2011, Russell King - ARM Linux wrote: > > On Wed, Jul 06, 2011 at 04:51:49PM +0200, Arnd Bergmann wrote: > > > On Wednesday 06 July 2011, Russell King - ARM Linux wrote: > > > > > > I don't see how. The pages get allocated from an unmapped area > > > or memory, mapped into the kernel address space as uncached or wc > > > and then cleared. This should be the same for lowmem or highmem > > > pages. > > > > You don't want to clear them via their uncached or WC mapping, but via > > their cached mapping _before_ they get their alternative mapping, and > > flush any cached out of that mapping - both L1 and L2 caches. > > But there can't be any other mapping, which is the whole point of > the exercise to use highmem. > Quoting from the new dma_alloc_area() function: > > c = arm_vmregion_alloc(&area->vm, align, size, > gfp & ~(__GFP_DMA | __GFP_HIGHMEM)); > if (!c) > return NULL; > memset((void *)c->vm_start, 0, size); > > area->vm here points to an uncached location, which means that > we already zero the data through the uncached mapping. I don't > see how it's getting worse than it is already. If you get a highmem page, because the cache is VIPT, that page might still be cached even if it wasn't mapped. With a VIVT cache we must flush the cache whenever a highmem page is unmapped. There is no such restriction with VIPT i.e. ARMv6 and above. Therefore to make sure the highmem page you get doesn't have cache lines associated to it, you must first map it cacheable, then perform cache invalidation on it, and eventually remap it as non-cacheable. This is necessary because there is no way to perform cache maintenance on L1 cache using physical addresses unfortunately. See commit 7e5a69e83b for an example of what this entails (fortunately commit 3e4d3af501 made things much easier and therefore commit 39af22a79 greatly simplified things). Nicolas ^ permalink raw reply [flat|nested] 46+ messages in thread
* RE: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-06 14:09 ` Arnd Bergmann 2011-07-06 14:23 ` Russell King - ARM Linux @ 2011-07-06 14:56 ` Marek Szyprowski 2011-07-06 15:37 ` Russell King - ARM Linux 1 sibling, 1 reply; 46+ messages in thread From: Marek Szyprowski @ 2011-07-06 14:56 UTC (permalink / raw) To: 'Arnd Bergmann' Cc: 'Russell King - ARM Linux', linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig, 'Daniel Walker', 'Jonathan Corbet', 'Mel Gorman', 'Chunsang Jeong', 'Michal Nazarewicz', 'Jesse Barker', 'Kyungmin Park', 'Ankita Garg', 'Andrew Morton', 'KAMEZAWA Hiroyuki' Hello, On Wednesday, July 06, 2011 4:09 PM Arnd Bergmann wrote: > On Wednesday 06 July 2011, Marek Szyprowski wrote: > > The only problem that might need to be resolved is GFP_ATOMIC allocation > > (updating page properties probably requires some locking), but it can be > > served from a special area which is created on boot without low-memory > > mapping at all. None sane driver will call dma_alloc_coherent(GFP_ATOMIC) > > for large buffers anyway. > > Would it be easier to start with a version that only allocated from memory > without a low-memory mapping at first? > > This would be similar to the approach that Russell's fix for the regular > dma_alloc_coherent has taken, except that you need to also allow the memory > to be used as highmem user pages. > > Maybe you can simply adapt the default location of the contiguous memory > are like this: > - make CONFIG_CMA depend on CONFIG_HIGHMEM on ARM, at compile time > - if ZONE_HIGHMEM exist during boot, put the CMA area in there > - otherwise, put the CMA area at the top end of lowmem, and change > the zone sizes so ZONE_HIGHMEM stretches over all of the CMA memory. This will not solve our problems. We need CMA also to create at least one device private area that for sure will be in low memory (video codec). I will rewrite ARM dma-mapping & CMA integration patch basing on the latest ARM for-next patches and add proof-of-concept of the solution presented in my previous mail (2-level page tables and unmapping pages from low-mem). Best regards -- Marek Szyprowski Samsung Poland R&D Center ^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-06 14:56 ` Marek Szyprowski @ 2011-07-06 15:37 ` Russell King - ARM Linux 2011-07-06 15:47 ` Marek Szyprowski 0 siblings, 1 reply; 46+ messages in thread From: Russell King - ARM Linux @ 2011-07-06 15:37 UTC (permalink / raw) To: Marek Szyprowski Cc: 'Arnd Bergmann', linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig, 'Daniel Walker', 'Jonathan Corbet', 'Mel Gorman', 'Chunsang Jeong', 'Michal Nazarewicz', 'Jesse Barker', 'Kyungmin Park', 'Ankita Garg', 'Andrew Morton', 'KAMEZAWA Hiroyuki' On Wed, Jul 06, 2011 at 04:56:23PM +0200, Marek Szyprowski wrote: > This will not solve our problems. We need CMA also to create at least one > device private area that for sure will be in low memory (video codec). You make these statements but you don't say why. Can you please explain why the video codec needs low memory - does it have a restricted number of memory address bits which it can manipulate? ^ permalink raw reply [flat|nested] 46+ messages in thread
* RE: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-06 15:37 ` Russell King - ARM Linux @ 2011-07-06 15:47 ` Marek Szyprowski 0 siblings, 0 replies; 46+ messages in thread From: Marek Szyprowski @ 2011-07-06 15:47 UTC (permalink / raw) To: 'Russell King - ARM Linux' Cc: 'Arnd Bergmann', linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig, 'Daniel Walker', 'Jonathan Corbet', 'Mel Gorman', 'Chunsang Jeong', 'Michal Nazarewicz', 'Jesse Barker', 'Kyungmin Park', 'Ankita Garg', 'Andrew Morton', 'KAMEZAWA Hiroyuki' Hello, On Wednesday, July 06, 2011 5:37 PM Russell King - ARM Linux wrote: > On Wed, Jul 06, 2011 at 04:56:23PM +0200, Marek Szyprowski wrote: > > This will not solve our problems. We need CMA also to create at least one > > device private area that for sure will be in low memory (video codec). > > You make these statements but you don't say why. Can you please > explain why the video codec needs low memory - does it have a > restricted number of memory address bits which it can manipulate? Nope, it only needs to put some type of memory buffers in first bank (effectively in 30000000-34ffffff area) and the others in the second bank (40000000-57ffffff area). The values are given for Samsung GONI board. Best regards -- Marek Szyprowski Samsung Poland R&D Center ^ permalink raw reply [flat|nested] 46+ messages in thread
* RE: [PATCH 6/8] drivers: add Contiguous Memory Allocator 2011-07-05 7:41 ` [PATCH 6/8] drivers: add " Marek Szyprowski 2011-07-05 10:24 ` Marek Szyprowski 2011-07-05 11:33 ` Russell King - ARM Linux @ 2011-07-14 12:29 ` Marek Szyprowski 2 siblings, 0 replies; 46+ messages in thread From: Marek Szyprowski @ 2011-07-14 12:29 UTC (permalink / raw) To: Marek Szyprowski, linux-kernel, linux-arm-kernel, linux-media, linux-mm, linaro-mm-sig Cc: 'Michal Nazarewicz', 'Kyungmin Park', 'Andrew Morton', 'KAMEZAWA Hiroyuki', 'Ankita Garg', 'Daniel Walker', 'Mel Gorman', 'Arnd Bergmann', 'Jesse Barker', 'Jonathan Corbet', 'Chunsang Jeong' Hello, I've just found two nasty bugs in this version of CMA. Sadly, both are the results of posting the patches in a big hurry. I'm really sorry. Alignment argument was not passed correctly to the bitmap_find_next_zero_area() function and there was an ugly bug in the dma_release_from_contiguous() function. On Tuesday, July 05, 2011 9:42 AM Marek Szyprowski wrote: > The Contiguous Memory Allocator is a set of helper functions for DMA > mapping framework that improves allocations of contiguous memory chunks. > > CMA grabs memory on system boot, marks it with CMA_MIGRATE_TYPE and > gives back to the system. Kernel is allowed to allocate movable pages > within CMA's managed memory so that it can be used for example for page > cache when DMA mapping do not use it. On dma_alloc_from_contiguous() > request such pages are migrated out of CMA area to free required > contiguous block and fulfill the request. This allows to allocate large > contiguous chunks of memory at any time assuming that there is enough > free memory available in the system. > > This code is heavily based on earlier works by Michal Nazarewicz. > > Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> > Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> > CC: Michal Nazarewicz <mina86@mina86.com> > --- > drivers/base/Kconfig | 77 +++++++++ > drivers/base/Makefile | 1 + > drivers/base/dma-contiguous.c | 367 > ++++++++++++++++++++++++++++++++++++++++ > include/linux/dma-contiguous.h | 104 +++++++++++ > 4 files changed, 549 insertions(+), 0 deletions(-) > create mode 100644 drivers/base/dma-contiguous.c > create mode 100644 include/linux/dma-contiguous.h > > diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig > index d57e8d0..95ae1a7 100644 > --- a/drivers/base/Kconfig > +++ b/drivers/base/Kconfig > @@ -168,4 +168,81 @@ config SYS_HYPERVISOR > bool > default n > > +config CMA > + bool "Contiguous Memory Allocator" > + depends HAVE_DMA_CONTIGUOUS && HAVE_MEMBLOCK > + select MIGRATION > + select CMA_MIGRATE_TYPE > + help > + This enables the Contiguous Memory Allocator which allows drivers > + to allocate big physically-contiguous blocks of memory for use with > + hardware components that do not support I/O map nor scatter-gather. > + > + For more information see <include/linux/dma-contiguous.h>. > + If unsure, say "n". > + > +if CMA > + > +config CMA_DEBUG > + bool "CMA debug messages (DEVELOPEMENT)" > + help > + Turns on debug messages in CMA. This produces KERN_DEBUG > + messages for every CMA call as well as various messages while > + processing calls such as dma_alloc_from_contiguous(). > + This option does not affect warning and error messages. > + > +comment "Default contiguous memory area size:" > + > +config CMA_SIZE_ABSOLUTE > + int "Absolute size (in MiB)" > + default 16 > + help > + Defines the size (in MiB) of the default memory area for Contiguous > + Memory Allocator. > + > +config CMA_SIZE_PERCENTAGE > + int "Percentage of total memory" > + default 10 > + help > + Defines the size of the default memory area for Contiguous Memory > + Allocator as a percentage of the total memory in the system. > + > +choice > + prompt "Selected region size" > + default CMA_SIZE_SEL_ABSOLUTE > + > +config CMA_SIZE_SEL_ABSOLUTE > + bool "Use absolute value only" > + > +config CMA_SIZE_SEL_PERCENTAGE > + bool "Use percentage value only" > + > +config CMA_SIZE_SEL_MIN > + bool "Use lower value (minimum)" > + > +config CMA_SIZE_SEL_MAX > + bool "Use higher value (maximum)" > + > +endchoice > + > +config CMA_ALIGNMENT > + int "Maximum PAGE_SIZE order of alignment for contiguous buffers" > + range 4 9 > + default 8 > + help > + DMA mapping framework by default aligns all buffers to the smallest > + PAGE_SIZE order which is greater than or equal to the requested > buffer > + size. This works well for buffers up to a few hundreds kilobytes, > but > + for larger buffers it just a memory waste. With this parameter you > can > + specify the maximum PAGE_SIZE order for contiguous buffers. Larger > + buffers will be aligned only to this specified order. The order is > + expressed as a power of two multiplied by the PAGE_SIZE. > + > + For example, if your system defaults to 4KiB pages, the order value > + of 8 means that the buffers will be aligned up to 1MiB only. > + > + If unsure, leave the default value "8". > + > +endif > + > endmenu > diff --git a/drivers/base/Makefile b/drivers/base/Makefile > index 4c5701c..be6aab4 100644 > --- a/drivers/base/Makefile > +++ b/drivers/base/Makefile > @@ -5,6 +5,7 @@ obj-y := core.o sys.o bus.o dd.o syscore.o \ > cpu.o firmware.o init.o map.o devres.o \ > attribute_container.o transport_class.o > obj-$(CONFIG_DEVTMPFS) += devtmpfs.o > +obj-$(CONFIG_CMA) += dma-contiguous.o > obj-y += power/ > obj-$(CONFIG_HAS_DMA) += dma-mapping.o > obj-$(CONFIG_HAVE_GENERIC_DMA_COHERENT) += dma-coherent.o > diff --git a/drivers/base/dma-contiguous.c b/drivers/base/dma-contiguous.c > new file mode 100644 > index 0000000..707b901 > --- /dev/null > +++ b/drivers/base/dma-contiguous.c > @@ -0,0 +1,367 @@ > +/* > + * Contiguous Memory Allocator for DMA mapping framework > + * Copyright (c) 2010-2011 by Samsung Electronics. > + * Written by: > + * Marek Szyprowski <m.szyprowski@samsung.com> > + * Michal Nazarewicz <mina86@mina86.com> > + * > + * This program is free software; you can redistribute it and/or > + * modify it under the terms of the GNU General Public License as > + * published by the Free Software Foundation; either version 2 of the > + * License or (at your optional) any later version of the license. > + */ > + > +#define pr_fmt(fmt) "cma: " fmt > + > +#ifdef CONFIG_CMA_DEBUG > +#ifndef DEBUG > +# define DEBUG > +#endif > +#endif > + > +#include <asm/page.h> > +#include <asm/sizes.h> > + > +#include <linux/memblock.h> > +#include <linux/err.h> > +#include <linux/mm.h> > +#include <linux/module.h> > +#include <linux/mutex.h> > +#include <linux/page-isolation.h> > +#include <linux/slab.h> > +#include <linux/swap.h> > +#include <linux/mm_types.h> > +#include <linux/dma-mapping.h> > +#include <linux/dma-contiguous.h> > + > +struct cma { > + unsigned long base_pfn; > + unsigned long count; > + unsigned long *bitmap; > +}; > + > +struct cma *dma_contiguous_default_area; > + > +static unsigned long size_abs = CONFIG_CMA_SIZE_ABSOLUTE * SZ_1M; > +static unsigned long size_percent = CONFIG_CMA_SIZE_PERCENTAGE; > +static long size_cmdline = -1; > + > +static int __init early_cma(char *p) > +{ > + pr_debug("%s(%s)\n", __func__, p); > + size_cmdline = memparse(p, &p); > + return 0; > +} > +early_param("cma", early_cma); > + > +/** > + * dma_contiguous_reserve() - reserve area for contiguous memory handling > + * > + * This funtion reserves memory from memblock subsystem. It should be > + * called by arch specific code once a memblock allocator has been > activated > + * and all other subsystems have already allocated/reserved memory. > + */ > +void __init dma_contiguous_reserve(void) > +{ > + struct memblock_region *reg; > + unsigned long selected_size = 0; > + unsigned long total_pages = 0; > + > + pr_debug("%s()\n", __func__); > + > + /* > + * We cannot use memblock_phys_mem_size() here, because > + * memblock_analyze() has not been called yet. > + */ > + for_each_memblock(memory, reg) > + total_pages += memblock_region_memory_end_pfn(reg) - > + memblock_region_memory_base_pfn(reg); > + > + size_percent *= (total_pages << PAGE_SHIFT) / 100; > + > + pr_debug("%s: available phys mem: %ld MiB\n", __func__, > + (total_pages << PAGE_SHIFT) / SZ_1M); > + > +#ifdef CONFIG_CMA_SIZE_SEL_ABSOLUTE > + selected_size = size_abs; > +#endif > +#ifdef CONFIG_CMA_SIZE_SEL_PERCENTAGE > + selected_size = size_percent; > +#endif > +#ifdef CONFIG_CMA_SIZE_SEL_MIN > + selected_size = min(size_abs, size_percent); > +#endif > +#ifdef CONFIG_CMA_SIZE_SEL_MAX > + selected_size = max(size_abs, size_percent); > +#endif > + > + if (size_cmdline != -1) > + selected_size = size_cmdline; > + > + if (!selected_size) > + return; > + > + pr_debug("%s: reserving %ld MiB for global area\n", __func__, > + selected_size / SZ_1M); > + > + dma_declare_contiguous(NULL, selected_size, 0); > +}; > + > +static DEFINE_MUTEX(cma_mutex); > + > +#ifdef CONFIG_DEBUG_VM > + > +static int __cma_activate_area(unsigned long base_pfn, unsigned long > count) > +{ > + unsigned long pfn = base_pfn; > + unsigned i = count; > + struct zone *zone; > + > + pr_debug("%s(0x%08lx+0x%lx)\n", __func__, base_pfn, count); > + > + VM_BUG_ON(!pfn_valid(pfn)); > + zone = page_zone(pfn_to_page(pfn)); > + > + do { > + VM_BUG_ON(!pfn_valid(pfn)); > + VM_BUG_ON(page_zone(pfn_to_page(pfn)) != zone); > + if (!(pfn & (pageblock_nr_pages - 1))) > + init_cma_reserved_pageblock(pfn_to_page(pfn)); > + ++pfn; > + } while (--i); > + > + return 0; > +} > + > +#else > + > +static int __cma_activate_area(unsigned long base_pfn, unsigned long > count) > +{ > + unsigned i = count >> pageblock_order; > + struct page *p = pfn_to_page(base_pfn); > + > + pr_debug("%s(0x%08lx+0x%lx)\n", __func__, base_pfn, count); > + > + do { > + init_cma_reserved_pageblock(p); > + p += pageblock_nr_pages; > + } while (--i); > + > + return 0; > +} > + > +#endif > + > +static struct cma *__cma_create_area(unsigned long base_pfn, > + unsigned long count) > +{ > + int bitmap_size = BITS_TO_LONGS(count) * sizeof(long); > + struct cma *cma; > + > + pr_debug("%s(0x%08lx+0x%lx)\n", __func__, base_pfn, count); > + > + cma = kmalloc(sizeof *cma, GFP_KERNEL); > + if (!cma) > + return ERR_PTR(-ENOMEM); > + > + cma->base_pfn = base_pfn; > + cma->count = count; > + cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL); > + > + if (!cma->bitmap) > + goto no_mem; > + > + __cma_activate_area(base_pfn, count); > + > + pr_debug("%s: returning <%p>\n", __func__, (void *)cma); > + return cma; > + > +no_mem: > + kfree(cma); > + return ERR_PTR(-ENOMEM); > +} > + > +static struct cma_reserved { > + unsigned long start; > + unsigned long size; > + struct device *dev; > +} cma_reserved[8] __initdata; > +static unsigned cma_reserved_count __initdata; > + > +static int __init __cma_init_reserved_areas(void) > +{ > + struct cma_reserved *r = cma_reserved; > + unsigned i = cma_reserved_count; > + > + pr_debug("%s()\n", __func__); > + > + for (; i; --i, ++r) { > + struct cma *cma; > + cma = __cma_create_area(page_to_pfn(phys_to_page(r->start)), > + r->size >> PAGE_SHIFT); > + if (!IS_ERR(cma)) { > + pr_debug("%s: created area %p\n", __func__, cma); > + if (r->dev) > + set_dev_cma_area(r->dev, cma); > + else > + dma_contiguous_default_area = cma; > + } > + } > + return 0; > +} > +core_initcall(__cma_init_reserved_areas); > + > +/** > + * dma_declare_contiguous() - reserve area for contiguous memory handling > + * for particular device > + * @dev: Pointer to device structure. > + * @size: Size of the reserved memory. > + * @start: Start address of the reserved memory (optional, 0 for any). > + * > + * This funtion reserves memory for specified device. It should be > + * called by board specific code once a memblock allocator has been > activated > + * and all other subsystems have already allocated/reserved memory. > + */ > +int __init dma_declare_contiguous(struct device *dev, unsigned long size, > + phys_addr_t start) > +{ > + struct cma_reserved *r = &cma_reserved[cma_reserved_count]; > + unsigned long alignment; > + > + pr_debug("%s(%p+%p)\n", __func__, (void *)start, (void *)size); > + > + /* Sanity checks */ > + if (cma_reserved_count == ARRAY_SIZE(cma_reserved)) > + return -ENOSPC; > + > + if (!size) > + return -EINVAL; > + > + /* Sanitise input arguments */ > + alignment = PAGE_SIZE << (MAX_ORDER + 1); > + start = ALIGN(start, alignment); > + size = ALIGN(size , alignment); > + > + /* Reserve memory */ > + if (start) { > + if (memblock_is_region_reserved(start, size) || > + memblock_reserve(start, size) < 0) > + return -EBUSY; > + } else { > + /* > + * Use __memblock_alloc_base() since > + * memblock_alloc_base() panic()s. > + */ > + u64 addr = __memblock_alloc_base(size, alignment, 0); > + if (!addr) { > + return -ENOMEM; > + } else if (addr + size > ~(unsigned long)0) { > + memblock_free(addr, size); > + return -EOVERFLOW; > + } else { > + start = addr; > + } > + } > + > + /* > + * Each reserved area must be initialised later, when more kernel > + * subsystems (like slab allocator) are available. > + */ > + r->start = start; > + r->size = size; > + r->dev = dev; > + cma_reserved_count++; > + printk(KERN_INFO "%s: reserved %ld MiB area at 0x%p\n", __func__, > + size / SZ_1M, (void *)start); > + return 0; > +} > + > +/** > + * dma_alloc_from_contiguous() - allocate pages from contiguous area > + * @dev: Pointer to device for which the allocation is performed. > + * @count: Requested number of pages. > + * @align: Requested alignment of pages (in PAGE_SIZE order). > + * > + * This funtion allocates memory buffer for specified device. It uses > + * device specific contiguous memory area if available or the default > + * global one. Requires architecture specific get_dev_cma_area() helper > + * function. > + */ > +struct page *dma_alloc_from_contiguous(struct device *dev, int count, > + unsigned int align) > +{ > + struct cma *cma = get_dev_cma_area(dev); > + unsigned long pfn, pageno; > + int ret; > + > + if (!cma) > + return NULL; > + > + if (align > CONFIG_CMA_ALIGNMENT) > + align = CONFIG_CMA_ALIGNMENT; > + > + pr_debug("%s(<%p>, %d/%d)\n", __func__, (void *)cma, count, align); > + > + if (!count) > + return NULL; > + > + mutex_lock(&cma_mutex); > + > + pageno = bitmap_find_next_zero_area(cma->bitmap, cma->count, 0, count, > + align); Fixed version: pageno = bitmap_find_next_zero_area(cma->bitmap, cma->count, 0, count, (1 << align) - 1); > + if (pageno >= cma->count) { > + ret = -ENOMEM; > + goto error; > + } > + bitmap_set(cma->bitmap, pageno, count); > + > + pfn = cma->base_pfn + pageno; > + ret = alloc_contig_range(pfn, pfn + count, 0, MIGRATE_CMA); > + if (ret) > + goto free; > + > + mutex_unlock(&cma_mutex); > + > + pr_debug("%s(): returning [%ld]\n", __func__, pfn); > + return pfn_to_page(pfn); > +free: > + bitmap_clear(cma->bitmap, pageno, count); > +error: > + mutex_unlock(&cma_mutex); > + return NULL; > +} > + > +/** > + * dma_release_from_contiguous() - release allocated pages > + * @dev: Pointer to device for which the pages were allocated. > + * @pages: Allocated pages. > + * @count: Number of allocated pages. > + * > + * This funtion reserves memory for specified device. It should be > + * called by board specific code once a memblock allocator has been > activated > + * and all other subsystems have already allocated/reserved memory. > + */ > +int dma_release_from_contiguous(struct device *dev, struct page *pages, > + int count) > +{ > + struct cma *cma = get_dev_cma_area(dev); > + unsigned long pfn; > + > + if (!cma || !pages) > + return 0; > + > + pr_debug("%s([%p])\n", __func__, (void *)pages); > + > + pfn = page_to_pfn(pages); > + > + if (pfn < cma->base_pfn || pfn >= cma->base_pfn + count) Fixed version: if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count) > + return 0; > + > + mutex_lock(&cma_mutex); > + > + bitmap_clear(cma->bitmap, pfn - cma->base_pfn, count); > + free_contig_pages(pages, count); > + > + mutex_unlock(&cma_mutex); > + return 1; > +} > diff --git a/include/linux/dma-contiguous.h b/include/linux/dma- > contiguous.h > new file mode 100644 > index 0000000..98312c9 > --- /dev/null > +++ b/include/linux/dma-contiguous.h > @@ -0,0 +1,104 @@ > +#ifndef __LINUX_CMA_H > +#define __LINUX_CMA_H > + > +/* > + * Contiguous Memory Allocator for DMA mapping framework > + * Copyright (c) 2010-2011 by Samsung Electronics. > + * Written by: > + * Marek Szyprowski <m.szyprowski@samsung.com> > + * Michal Nazarewicz <mina86@mina86.com> > + * > + * This program is free software; you can redistribute it and/or > + * modify it under the terms of the GNU General Public License as > + * published by the Free Software Foundation; either version 2 of the > + * License or (at your optional) any later version of the license. > + */ > + > +/* > + * Contiguous Memory Allocator > + * > + * The Contiguous Memory Allocator (CMA) makes it possible to > + * allocate big contiguous chunks of memory after the system has > + * booted. > + * > + * Why is it needed? > + * > + * Various devices on embedded systems have no scatter-getter and/or > + * IO map support and require contiguous blocks of memory to > + * operate. They include devices such as cameras, hardware video > + * coders, etc. > + * > + * Such devices often require big memory buffers (a full HD frame > + * is, for instance, more then 2 mega pixels large, i.e. more than 6 > + * MB of memory), which makes mechanisms such as kmalloc() or > + * alloc_page() ineffective. > + * > + * At the same time, a solution where a big memory region is > + * reserved for a device is suboptimal since often more memory is > + * reserved then strictly required and, moreover, the memory is > + * inaccessible to page system even if device drivers don't use it. > + * > + * CMA tries to solve this issue by operating on memory regions > + * where only movable pages can be allocated from. This way, kernel > + * can use the memory for pagecache and when device driver requests > + * it, allocated pages can be migrated. > + * > + * Driver usage > + * > + * CMA should not be used by the device drivers directly. It is > + * only a helper framework for dma-mapping subsystem. > + * > + * For more information, see kernel-docs in drivers/base/dma- > contiguous.c > + */ > + > +#ifdef __KERNEL__ > + > +struct cma; > +struct page; > +struct device; > + > +#ifdef CONFIG_CMA > + > +extern struct cma *dma_contiguous_default_area; > + > +void dma_contiguous_reserve(void); > +int dma_declare_contiguous(struct device *dev, unsigned long size, > + phys_addr_t base); > + > +struct page *dma_alloc_from_contiguous(struct device *dev, int count, > + unsigned int order); > +int dma_release_from_contiguous(struct device *dev, struct page *pages, > + int count); > + > +#else > + > +#define dna_contiguous_default_area NULL > + > +static inline void dma_contiguous_reserve(void) { } > + > +static inline > +int dma_declare_contiguous(struct device *dev, unsigned long size, > + unsigned long base) > +{ > + return -EINVAL; > +} > + > +static inline > +struct page *dma_alloc_from_contiguous(struct device *dev, int count, > + unsigned int order) > +{ > + return NULL; > +} > + > +static inline > +int dma_release_from_contiguous(struct device *dev, struct page *pages, > + int count) > +{ > + return 0; > +} > + > +#endif > + > +#endif > + > +#endif > -- > 1.7.1.569.g6f426 Best regards -- Marek Szyprowski Samsung Poland R&D Center ^ permalink raw reply [flat|nested] 46+ messages in thread
end of thread, other threads:[~2011-09-26 13:01 UTC | newest] Thread overview: 46+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2011-08-19 14:27 [PATCHv15 0/8] Contiguous Memory Allocator Marek Szyprowski 2011-08-19 14:27 ` [PATCH 1/8] mm: move some functions from memory_hotplug.c to page_isolation.c Marek Szyprowski 2011-08-19 14:27 ` [PATCH 2/8] mm: alloc_contig_freed_pages() added Marek Szyprowski 2011-09-08 18:05 ` Dave Hansen 2011-09-21 13:17 ` Michal Nazarewicz 2011-09-21 14:07 ` Dave Hansen 2011-09-21 15:19 ` [PATCH 1/3] fixup! " Michal Nazarewicz 2011-09-21 15:45 ` Dave Hansen 2011-09-21 16:26 ` Michal Nazarewicz 2011-09-21 16:30 ` Dave Hansen 2011-08-19 14:27 ` [PATCH 3/8] mm: alloc_contig_range() added Marek Szyprowski 2011-08-19 14:27 ` [PATCH 4/8] mm: MIGRATE_CMA migration type added Marek Szyprowski 2011-08-19 14:27 ` [PATCH 5/8] mm: MIGRATE_CMA isolation functions added Marek Szyprowski 2011-08-19 14:27 ` [PATCH 6/8] drivers: add Contiguous Memory Allocator Marek Szyprowski 2011-08-19 14:27 ` [PATCH 7/8] ARM: integrate CMA with DMA-mapping subsystem Marek Szyprowski [not found] ` <CAMjpGUch=ogFQwBLqOukKVnyh60600jw5tMq-KYeNGSZ2PLQpA@mail.gmail.com> 2011-09-21 13:47 ` Marek Szyprowski 2011-08-19 14:27 ` [PATCH 8/8] ARM: S5PV210: example of CMA private area for FIMC device on Goni board Marek Szyprowski -- strict thread matches above, loose matches on Subject: below -- 2011-07-20 8:57 [PATCHv12 0/8] Contiguous Memory Allocator Marek Szyprowski 2011-07-20 8:57 ` [PATCH 6/8] drivers: add " Marek Szyprowski 2011-07-05 7:41 [PATCHv11 0/8] " Marek Szyprowski 2011-07-05 7:41 ` [PATCH 6/8] drivers: add " Marek Szyprowski 2011-07-05 10:24 ` Marek Szyprowski 2011-07-05 11:33 ` Russell King - ARM Linux 2011-07-05 12:27 ` Arnd Bergmann 2011-07-05 12:30 ` Russell King - ARM Linux 2011-07-05 13:58 ` Arnd Bergmann 2011-07-08 17:25 ` Russell King - ARM Linux 2011-07-12 13:39 ` Arnd Bergmann 2011-08-03 17:43 ` James Bottomley 2011-09-26 12:06 ` Marek Szyprowski 2011-09-26 13:00 ` Russell King - ARM Linux 2011-07-06 13:58 ` Marek Szyprowski 2011-07-06 14:09 ` Arnd Bergmann 2011-07-06 14:23 ` Russell King - ARM Linux 2011-07-06 14:51 ` Arnd Bergmann 2011-07-06 15:48 ` Russell King - ARM Linux 2011-07-06 16:05 ` Christoph Lameter 2011-07-06 16:09 ` Michal Nazarewicz 2011-07-06 16:19 ` Christoph Lameter 2011-07-06 17:15 ` Russell King - ARM Linux 2011-07-06 19:03 ` Christoph Lameter 2011-07-06 17:02 ` Russell King - ARM Linux 2011-07-06 16:31 ` Arnd Bergmann 2011-07-06 19:10 ` Nicolas Pitre 2011-07-06 14:56 ` Marek Szyprowski 2011-07-06 15:37 ` Russell King - ARM Linux 2011-07-06 15:47 ` Marek Szyprowski 2011-07-14 12:29 ` Marek Szyprowski
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