From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752829Ab2JFOSo (ORCPT ); Sat, 6 Oct 2012 10:18:44 -0400 Received: from mail-pa0-f46.google.com ([209.85.220.46]:42942 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750993Ab2JFOSl (ORCPT ); Sat, 6 Oct 2012 10:18:41 -0400 Message-ID: <50703DAA.20407@gmail.com> Date: Sat, 06 Oct 2012 22:18:18 +0800 From: Ni zhan Chen User-Agent: Mozilla/5.0 (X11; Linux i686; rv:15.0) Gecko/20120912 Thunderbird/15.0.1 MIME-Version: 1.0 To: Yasuaki Ishimatsu CC: x86@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-acpi@vger.kernel.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-ia64@vger.kernel.org, cmetcalf@tilera.com, sparclinux@vger.kernel.org, rientjes@google.com, liuj97@gmail.com, len.brown@intel.com, benh@kernel.crashing.org, paulus@samba.org, cl@linux.com, minchan.kim@gmail.com, akpm@linux-foundation.org, kosaki.motohiro@jp.fujitsu.com, Wen Congyang Subject: Re: [RFC v9 PATCH 16/21] memory-hotplug: free memmap of sparse-vmemmap References: <1346837155-534-1-git-send-email-wency@cn.fujitsu.com> <1346837155-534-17-git-send-email-wency@cn.fujitsu.com> <506A6BDC.3010400@gmail.com> <506D2C1C.5060706@jp.fujitsu.com> In-Reply-To: <506D2C1C.5060706@jp.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/04/2012 02:26 PM, Yasuaki Ishimatsu wrote: > Hi Chen, > > Sorry for late reply. > > 2012/10/02 13:21, Ni zhan Chen wrote: >> On 09/05/2012 05:25 PM, wency@cn.fujitsu.com wrote: >>> From: Yasuaki Ishimatsu >>> >>> All pages of virtual mapping in removed memory cannot be freed, >>> since some pages >>> used as PGD/PUD includes not only removed memory but also other >>> memory. So the >>> patch checks whether page can be freed or not. >>> >>> How to check whether page can be freed or not? >>> 1. When removing memory, the page structs of the revmoved memory >>> are filled >>> with 0FD. >>> 2. All page structs are filled with 0xFD on PT/PMD, PT/PMD can be >>> cleared. >>> In this case, the page used as PT/PMD can be freed. >>> >>> Applying patch, __remove_section() of CONFIG_SPARSEMEM_VMEMMAP is >>> integrated >>> into one. So __remove_section() of CONFIG_SPARSEMEM_VMEMMAP is deleted. >>> >>> Note: vmemmap_kfree() and vmemmap_free_bootmem() are not >>> implemented for ia64, >>> ppc, s390, and sparc. >>> >>> CC: David Rientjes >>> CC: Jiang Liu >>> CC: Len Brown >>> CC: Benjamin Herrenschmidt >>> CC: Paul Mackerras >>> CC: Christoph Lameter >>> Cc: Minchan Kim >>> CC: Andrew Morton >>> CC: KOSAKI Motohiro >>> CC: Wen Congyang >>> Signed-off-by: Yasuaki Ishimatsu >>> --- >>> arch/ia64/mm/discontig.c | 8 +++ >>> arch/powerpc/mm/init_64.c | 8 +++ >>> arch/s390/mm/vmem.c | 8 +++ >>> arch/sparc/mm/init_64.c | 8 +++ >>> arch/x86/mm/init_64.c | 119 >>> +++++++++++++++++++++++++++++++++++++++++++++ >>> include/linux/mm.h | 2 + >>> mm/memory_hotplug.c | 17 +------ >>> mm/sparse.c | 5 +- >>> 8 files changed, 158 insertions(+), 17 deletions(-) >>> >>> diff --git a/arch/ia64/mm/discontig.c b/arch/ia64/mm/discontig.c >>> index 33943db..0d23b69 100644 >>> --- a/arch/ia64/mm/discontig.c >>> +++ b/arch/ia64/mm/discontig.c >>> @@ -823,6 +823,14 @@ int __meminit vmemmap_populate(struct page >>> *start_page, >>> return vmemmap_populate_basepages(start_page, size, node); >>> } >>> +void vmemmap_kfree(struct page *memmap, unsigned long nr_pages) >>> +{ >>> +} >>> + >>> +void vmemmap_free_bootmem(struct page *memmap, unsigned long nr_pages) >>> +{ >>> +} >>> + >>> void register_page_bootmem_memmap(unsigned long section_nr, >>> struct page *start_page, unsigned long size) >>> { >>> diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c >>> index 3690c44..835a2b3 100644 >>> --- a/arch/powerpc/mm/init_64.c >>> +++ b/arch/powerpc/mm/init_64.c >>> @@ -299,6 +299,14 @@ int __meminit vmemmap_populate(struct page >>> *start_page, >>> return 0; >>> } >>> +void vmemmap_kfree(struct page *memmap, unsigned long nr_pages) >>> +{ >>> +} >>> + >>> +void vmemmap_free_bootmem(struct page *memmap, unsigned long nr_pages) >>> +{ >>> +} >>> + >>> void register_page_bootmem_memmap(unsigned long section_nr, >>> struct page *start_page, unsigned long size) >>> { >>> diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c >>> index eda55cd..4b42b0b 100644 >>> --- a/arch/s390/mm/vmem.c >>> +++ b/arch/s390/mm/vmem.c >>> @@ -227,6 +227,14 @@ out: >>> return ret; >>> } >>> +void vmemmap_kfree(struct page *memmap, unsigned long nr_pages) >>> +{ >>> +} >>> + >>> +void vmemmap_free_bootmem(struct page *memmap, unsigned long nr_pages) >>> +{ >>> +} >>> + >>> void register_page_bootmem_memmap(unsigned long section_nr, >>> struct page *start_page, unsigned long size) >>> { >>> diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c >>> index add1cc7..1384826 100644 >>> --- a/arch/sparc/mm/init_64.c >>> +++ b/arch/sparc/mm/init_64.c >>> @@ -2078,6 +2078,14 @@ void __meminit vmemmap_populate_print_last(void) >>> } >>> } >>> +void vmemmap_kfree(struct page *memmap, unsigned long nr_pages) >>> +{ >>> +} >>> + >>> +void vmemmap_free_bootmem(struct page *memmap, unsigned long nr_pages) >>> +{ >>> +} >>> + >>> void register_page_bootmem_memmap(unsigned long section_nr, >>> struct page *start_page, unsigned long size) >>> { >>> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c >>> index 0075592..4e8f8a4 100644 >>> --- a/arch/x86/mm/init_64.c >>> +++ b/arch/x86/mm/init_64.c >>> @@ -1138,6 +1138,125 @@ vmemmap_populate(struct page *start_page, >>> unsigned long size, int node) >>> return 0; >>> } >>> +#define PAGE_INUSE 0xFD >>> + >>> +unsigned long find_and_clear_pte_page(unsigned long addr, unsigned >>> long end, >>> + struct page **pp, int *page_size) >>> +{ >>> + pgd_t *pgd; >>> + pud_t *pud; >>> + pmd_t *pmd; >>> + pte_t *pte; >>> + void *page_addr; >>> + unsigned long next; >>> + >>> + *pp = NULL; >>> + >>> + pgd = pgd_offset_k(addr); >>> + if (pgd_none(*pgd)) >>> + return pgd_addr_end(addr, end); >>> + >>> + pud = pud_offset(pgd, addr); >>> + if (pud_none(*pud)) >>> + return pud_addr_end(addr, end); >>> + >>> + if (!cpu_has_pse) { >>> + next = (addr + PAGE_SIZE) & PAGE_MASK; >>> + pmd = pmd_offset(pud, addr); >>> + if (pmd_none(*pmd)) >>> + return next; >>> + >>> + pte = pte_offset_kernel(pmd, addr); >>> + if (pte_none(*pte)) >>> + return next; >>> + >>> + *page_size = PAGE_SIZE; >>> + *pp = pte_page(*pte); >>> + } else { >>> + next = pmd_addr_end(addr, end); >>> + >>> + pmd = pmd_offset(pud, addr); >>> + if (pmd_none(*pmd)) >>> + return next; >>> + >>> + *page_size = PMD_SIZE; >>> + *pp = pmd_page(*pmd); >>> + } >>> + >>> + /* >>> + * Removed page structs are filled with 0xFD. >>> + */ >>> + memset((void *)addr, PAGE_INUSE, next - addr); >>> + >>> + page_addr = page_address(*pp); >>> + >>> + /* >>> + * Check the page is filled with 0xFD or not. >>> + * memchr_inv() returns the address. In this case, we cannot >>> + * clear PTE/PUD entry, since the page is used by other. >>> + * So we cannot also free the page. >>> + * >>> + * memchr_inv() returns NULL. In this case, we can clear >>> + * PTE/PUD entry, since the page is not used by other. >>> + * So we can also free the page. >>> + */ >>> + if (memchr_inv(page_addr, PAGE_INUSE, *page_size)) { >>> + *pp = NULL; >>> + return next; >>> + } >>> + >> >> Hi Yasuaki, >> >> why call memchr_inv check after memset, this time the page can always >> be filled with 0xFD. > > The page is not always filled with 0xFD. find_and_clear_pte_page() > is calld in each section. So the function fills the page > section size/sizeof(page) byte with 0xFD one time. Thus if section > size is > small, the page is filled with 0xFD. Hi Yasuaki, But when section size will be small? Regards, Chen > > Thanks, > Yasuaki Ishimatsu > > >>> + if (!cpu_has_pse) >>> + pte_clear(&init_mm, addr, pte); >>> + else >>> + pmd_clear(pmd); >>> + >>> + return next; >>> +} >>> + >>> +void vmemmap_kfree(struct page *memmap, unsigned long nr_pages) >>> +{ >>> + unsigned long addr = (unsigned long)memmap; >>> + unsigned long end = (unsigned long)(memmap + nr_pages); >>> + unsigned long next; >>> + struct page *page; >>> + int page_size; >>> + >>> + for (; addr < end; addr = next) { >>> + page = NULL; >>> + page_size = 0; >>> + next = find_and_clear_pte_page(addr, end, &page, &page_size); >>> + if (!page) >>> + continue; >>> + >>> + free_pages((unsigned long)page_address(page), >>> + get_order(page_size)); >>> + __flush_tlb_one(addr); >>> + } >>> +} >>> + >>> +void vmemmap_free_bootmem(struct page *memmap, unsigned long nr_pages) >>> +{ >>> + unsigned long addr = (unsigned long)memmap; >>> + unsigned long end = (unsigned long)(memmap + nr_pages); >>> + unsigned long next; >>> + struct page *page; >>> + int page_size; >>> + unsigned long magic; >>> + >>> + for (; addr < end; addr = next) { >>> + page = NULL; >>> + page_size = 0; >>> + next = find_and_clear_pte_page(addr, end, &page, &page_size); >>> + if (!page) >>> + continue; >>> + >>> + magic = (unsigned long) page->lru.next; >>> + if (magic == SECTION_INFO) >>> + put_page_bootmem(page); >>> + flush_tlb_kernel_range(addr, end); >>> + } >>> +} >>> + >>> void register_page_bootmem_memmap(unsigned long section_nr, >>> struct page *start_page, unsigned long size) >>> { >>> diff --git a/include/linux/mm.h b/include/linux/mm.h >>> index c607913..fb0d1fc 100644 >>> --- a/include/linux/mm.h >>> +++ b/include/linux/mm.h >>> @@ -1620,6 +1620,8 @@ int vmemmap_populate(struct page *start_page, >>> unsigned long pages, int node); >>> void vmemmap_populate_print_last(void); >>> void register_page_bootmem_memmap(unsigned long section_nr, struct >>> page *map, >>> unsigned long size); >>> +void vmemmap_kfree(struct page *memmpa, unsigned long nr_pages); >>> +void vmemmap_free_bootmem(struct page *memmpa, unsigned long >>> nr_pages); >>> enum mf_flags { >>> MF_COUNT_INCREASED = 1 << 0, >>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c >>> index 647a7f2..c54922c 100644 >>> --- a/mm/memory_hotplug.c >>> +++ b/mm/memory_hotplug.c >>> @@ -308,19 +308,6 @@ static int __meminit __add_section(int nid, >>> struct zone *zone, >>> return register_new_memory(nid, >>> __pfn_to_section(phys_start_pfn)); >>> } >>> -#ifdef CONFIG_SPARSEMEM_VMEMMAP >>> -static int __remove_section(struct zone *zone, struct mem_section *ms) >>> -{ >>> - int ret = -EINVAL; >>> - >>> - if (!valid_section(ms)) >>> - return ret; >>> - >>> - ret = unregister_memory_section(ms); >>> - >>> - return ret; >>> -} >>> -#else >>> static int __remove_section(struct zone *zone, struct mem_section >>> *ms) >>> { >>> unsigned long flags; >>> @@ -337,9 +324,9 @@ static int __remove_section(struct zone *zone, >>> struct mem_section *ms) >>> pgdat_resize_lock(pgdat, &flags); >>> sparse_remove_one_section(zone, ms); >>> pgdat_resize_unlock(pgdat, &flags); >>> - return 0; >>> + >>> + return ret; >>> } >>> -#endif >>> /* >>> * Reasonably generic function for adding memory. It is >>> diff --git a/mm/sparse.c b/mm/sparse.c >>> index fac95f2..ab9d755 100644 >>> --- a/mm/sparse.c >>> +++ b/mm/sparse.c >>> @@ -613,12 +613,13 @@ static inline struct page >>> *kmalloc_section_memmap(unsigned long pnum, int nid, >>> /* This will make the necessary allocations eventually. */ >>> return sparse_mem_map_populate(pnum, nid); >>> } >>> -static void __kfree_section_memmap(struct page *memmap, unsigned >>> long nr_pages) >>> +static void __kfree_section_memmap(struct page *page, unsigned long >>> nr_pages) >>> { >>> - return; /* XXX: Not implemented yet */ >>> + vmemmap_kfree(page, nr_pages); >>> } >>> static void free_map_bootmem(struct page *page, unsigned long >>> nr_pages) >>> { >>> + vmemmap_free_bootmem(page, nr_pages); >>> } >>> #else >>> static struct page *__kmalloc_section_memmap(unsigned long nr_pages) >> > > >