From: John Hubbard <jhubbard@nvidia.com> To: Balbir Singh <bsingharora@gmail.com> Cc: "Andrew Morton" <akpm@linux-foundation.org>, "Jérôme Glisse" <jglisse@redhat.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, linux-mm <linux-mm@kvack.org>, "Naoya Horiguchi" <n-horiguchi@ah.jp.nec.com>, "David Nellans" <dnellans@nvidia.com>, "Evgeny Baskakov" <ebaskakov@nvidia.com>, "Mark Hairgrove" <mhairgrove@nvidia.com>, "Sherry Cheung" <SCheung@nvidia.com>, "Subhash Gutti" <sgutti@nvidia.com> Subject: Re: [HMM 07/16] mm/migrate: new memory migration helper for use with device memory v4 Date: Thu, 16 Mar 2017 17:57:35 -0700 [thread overview] Message-ID: <94e0d115-7deb-c748-3dc2-60d6289e6551@nvidia.com> (raw) In-Reply-To: <CAKTCnzmYob5uq11zkJE781BX9rDH9EYM7zxHH+ZMtTs4D5kkiQ@mail.gmail.com> On 03/16/2017 05:45 PM, Balbir Singh wrote: > On Fri, Mar 17, 2017 at 11:22 AM, John Hubbard <jhubbard@nvidia.com> wrote: >> On 03/16/2017 04:05 PM, Andrew Morton wrote: >>> >>> On Thu, 16 Mar 2017 12:05:26 -0400 Jérôme Glisse <jglisse@redhat.com> >>> wrote: >>> >>>> +static inline struct page *migrate_pfn_to_page(unsigned long mpfn) >>>> +{ >>>> + if (!(mpfn & MIGRATE_PFN_VALID)) >>>> + return NULL; >>>> + return pfn_to_page(mpfn & MIGRATE_PFN_MASK); >>>> +} >>> >>> >>> i386 allnoconfig: >>> >>> In file included from mm/page_alloc.c:61: >>> ./include/linux/migrate.h: In function 'migrate_pfn_to_page': >>> ./include/linux/migrate.h:139: warning: left shift count >= width of type >>> ./include/linux/migrate.h:141: warning: left shift count >= width of type >>> ./include/linux/migrate.h: In function 'migrate_pfn_size': >>> ./include/linux/migrate.h:146: warning: left shift count >= width of type >>> >> >> It seems clear that this was never meant to work with < 64-bit pfns: >> >> // migrate.h excerpt: >> #define MIGRATE_PFN_VALID (1UL << (BITS_PER_LONG_LONG - 1)) >> #define MIGRATE_PFN_MIGRATE (1UL << (BITS_PER_LONG_LONG - 2)) >> #define MIGRATE_PFN_HUGE (1UL << (BITS_PER_LONG_LONG - 3)) >> #define MIGRATE_PFN_LOCKED (1UL << (BITS_PER_LONG_LONG - 4)) >> #define MIGRATE_PFN_WRITE (1UL << (BITS_PER_LONG_LONG - 5)) >> #define MIGRATE_PFN_DEVICE (1UL << (BITS_PER_LONG_LONG - 6)) >> #define MIGRATE_PFN_ERROR (1UL << (BITS_PER_LONG_LONG - 7)) >> #define MIGRATE_PFN_MASK ((1UL << (BITS_PER_LONG_LONG - PAGE_SHIFT)) >> - 1) >> >> ...obviously, there is not enough room for these flags, in a 32-bit pfn. >> >> So, given the current HMM design, I think we are going to have to provide a >> 32-bit version of these routines (migrate_pfn_to_page, and related) that is >> a no-op, right? > > Or make the HMM Kconfig feature 64BIT only by making it depend on 64BIT? > Yes, that was my first reaction too, but these particular routines are aspiring to be generic routines--in fact, you have had an influence there, because these might possibly help with NUMA migrations. :) So it would look odd to see this: #ifdef CONFIG_HMM int migrate_vma(const struct migrate_vma_ops *ops, struct vm_area_struct *vma, unsigned long mentries, unsigned long start, unsigned long end, unsigned long *src, unsigned long *dst, void *private) { //...implementation #endif ...because migrate_vma() does not sound HMM-specific, and it is, after all, in migrate.h and migrate.c. We probably want this a more generic approach (not sure if I've picked exactly the right token to #ifdef on, but it's close): #ifdef CONFIG_64BIT int migrate_vma(const struct migrate_vma_ops *ops, struct vm_area_struct *vma, unsigned long mentries, unsigned long start, unsigned long end, unsigned long *src, unsigned long *dst, void *private) { /* ... full implementation */ } #else int migrate_vma(const struct migrate_vma_ops *ops, struct vm_area_struct *vma, unsigned long mentries, unsigned long start, unsigned long end, unsigned long *src, unsigned long *dst, void *private) { return -EINVAL; /* or something more appropriate */ } #endif thanks John Hubbard NVIDIA > > Balbir Singh >
WARNING: multiple messages have this Message-ID (diff)
From: John Hubbard <jhubbard@nvidia.com> To: Balbir Singh <bsingharora@gmail.com> Cc: "Andrew Morton" <akpm@linux-foundation.org>, "Jérôme Glisse" <jglisse@redhat.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, linux-mm <linux-mm@kvack.org>, "Naoya Horiguchi" <n-horiguchi@ah.jp.nec.com>, "David Nellans" <dnellans@nvidia.com>, "Evgeny Baskakov" <ebaskakov@nvidia.com>, "Mark Hairgrove" <mhairgrove@nvidia.com>, "Sherry Cheung" <SCheung@nvidia.com>, "Subhash Gutti" <sgutti@nvidia.com> Subject: Re: [HMM 07/16] mm/migrate: new memory migration helper for use with device memory v4 Date: Thu, 16 Mar 2017 17:57:35 -0700 [thread overview] Message-ID: <94e0d115-7deb-c748-3dc2-60d6289e6551@nvidia.com> (raw) In-Reply-To: <CAKTCnzmYob5uq11zkJE781BX9rDH9EYM7zxHH+ZMtTs4D5kkiQ@mail.gmail.com> On 03/16/2017 05:45 PM, Balbir Singh wrote: > On Fri, Mar 17, 2017 at 11:22 AM, John Hubbard <jhubbard@nvidia.com> wrote: >> On 03/16/2017 04:05 PM, Andrew Morton wrote: >>> >>> On Thu, 16 Mar 2017 12:05:26 -0400 Jérôme Glisse <jglisse@redhat.com> >>> wrote: >>> >>>> +static inline struct page *migrate_pfn_to_page(unsigned long mpfn) >>>> +{ >>>> + if (!(mpfn & MIGRATE_PFN_VALID)) >>>> + return NULL; >>>> + return pfn_to_page(mpfn & MIGRATE_PFN_MASK); >>>> +} >>> >>> >>> i386 allnoconfig: >>> >>> In file included from mm/page_alloc.c:61: >>> ./include/linux/migrate.h: In function 'migrate_pfn_to_page': >>> ./include/linux/migrate.h:139: warning: left shift count >= width of type >>> ./include/linux/migrate.h:141: warning: left shift count >= width of type >>> ./include/linux/migrate.h: In function 'migrate_pfn_size': >>> ./include/linux/migrate.h:146: warning: left shift count >= width of type >>> >> >> It seems clear that this was never meant to work with < 64-bit pfns: >> >> // migrate.h excerpt: >> #define MIGRATE_PFN_VALID (1UL << (BITS_PER_LONG_LONG - 1)) >> #define MIGRATE_PFN_MIGRATE (1UL << (BITS_PER_LONG_LONG - 2)) >> #define MIGRATE_PFN_HUGE (1UL << (BITS_PER_LONG_LONG - 3)) >> #define MIGRATE_PFN_LOCKED (1UL << (BITS_PER_LONG_LONG - 4)) >> #define MIGRATE_PFN_WRITE (1UL << (BITS_PER_LONG_LONG - 5)) >> #define MIGRATE_PFN_DEVICE (1UL << (BITS_PER_LONG_LONG - 6)) >> #define MIGRATE_PFN_ERROR (1UL << (BITS_PER_LONG_LONG - 7)) >> #define MIGRATE_PFN_MASK ((1UL << (BITS_PER_LONG_LONG - PAGE_SHIFT)) >> - 1) >> >> ...obviously, there is not enough room for these flags, in a 32-bit pfn. >> >> So, given the current HMM design, I think we are going to have to provide a >> 32-bit version of these routines (migrate_pfn_to_page, and related) that is >> a no-op, right? > > Or make the HMM Kconfig feature 64BIT only by making it depend on 64BIT? > Yes, that was my first reaction too, but these particular routines are aspiring to be generic routines--in fact, you have had an influence there, because these might possibly help with NUMA migrations. :) So it would look odd to see this: #ifdef CONFIG_HMM int migrate_vma(const struct migrate_vma_ops *ops, struct vm_area_struct *vma, unsigned long mentries, unsigned long start, unsigned long end, unsigned long *src, unsigned long *dst, void *private) { //...implementation #endif ...because migrate_vma() does not sound HMM-specific, and it is, after all, in migrate.h and migrate.c. We probably want this a more generic approach (not sure if I've picked exactly the right token to #ifdef on, but it's close): #ifdef CONFIG_64BIT int migrate_vma(const struct migrate_vma_ops *ops, struct vm_area_struct *vma, unsigned long mentries, unsigned long start, unsigned long end, unsigned long *src, unsigned long *dst, void *private) { /* ... full implementation */ } #else int migrate_vma(const struct migrate_vma_ops *ops, struct vm_area_struct *vma, unsigned long mentries, unsigned long start, unsigned long end, unsigned long *src, unsigned long *dst, void *private) { return -EINVAL; /* or something more appropriate */ } #endif thanks John Hubbard NVIDIA > > Balbir Singh > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2017-03-17 1:00 UTC|newest] Thread overview: 90+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-03-16 16:05 [HMM 00/16] HMM (Heterogeneous Memory Management) v18 Jérôme Glisse 2017-03-16 16:05 ` Jérôme Glisse 2017-03-16 16:05 ` [HMM 01/16] mm/memory/hotplug: convert device bool to int to allow for more flags v3 Jérôme Glisse 2017-03-16 16:05 ` Jérôme Glisse 2017-03-19 20:08 ` Mel Gorman 2017-03-19 20:08 ` Mel Gorman 2017-03-16 16:05 ` [HMM 02/16] mm/put_page: move ref decrement to put_zone_device_page() Jérôme Glisse 2017-03-16 16:05 ` Jérôme Glisse 2017-03-19 20:08 ` Mel Gorman 2017-03-19 20:08 ` Mel Gorman 2017-03-16 16:05 ` [HMM 03/16] mm/ZONE_DEVICE/free-page: callback when page is freed v3 Jérôme Glisse 2017-03-16 16:05 ` Jérôme Glisse 2017-03-19 20:08 ` Mel Gorman 2017-03-19 20:08 ` Mel Gorman 2017-03-16 16:05 ` [HMM 04/16] mm/ZONE_DEVICE/unaddressable: add support for un-addressable device memory v3 Jérôme Glisse 2017-03-16 16:05 ` Jérôme Glisse 2017-03-19 20:09 ` Mel Gorman 2017-03-19 20:09 ` Mel Gorman 2017-03-16 16:05 ` [HMM 05/16] mm/ZONE_DEVICE/x86: add support for un-addressable device memory Jérôme Glisse 2017-03-16 16:05 ` Jérôme Glisse 2017-03-16 16:05 ` [HMM 06/16] mm/migrate: add new boolean copy flag to migratepage() callback Jérôme Glisse 2017-03-16 16:05 ` Jérôme Glisse 2017-03-19 20:09 ` Mel Gorman 2017-03-19 20:09 ` Mel Gorman 2017-03-16 16:05 ` [HMM 07/16] mm/migrate: new memory migration helper for use with device memory v4 Jérôme Glisse 2017-03-16 16:05 ` Jérôme Glisse 2017-03-16 16:24 ` Reza Arbab 2017-03-16 16:24 ` Reza Arbab 2017-03-16 20:58 ` Balbir Singh 2017-03-16 20:58 ` Balbir Singh 2017-03-16 23:05 ` Andrew Morton 2017-03-16 23:05 ` Andrew Morton 2017-03-17 0:22 ` John Hubbard 2017-03-17 0:22 ` John Hubbard 2017-03-17 0:45 ` Balbir Singh 2017-03-17 0:45 ` Balbir Singh 2017-03-17 0:57 ` John Hubbard [this message] 2017-03-17 0:57 ` John Hubbard 2017-03-17 1:52 ` Jerome Glisse 2017-03-17 1:52 ` Jerome Glisse 2017-03-17 3:32 ` Andrew Morton 2017-03-17 3:32 ` Andrew Morton 2017-03-17 3:42 ` Balbir Singh 2017-03-17 3:42 ` Balbir Singh 2017-03-17 4:51 ` Balbir Singh 2017-03-17 4:51 ` Balbir Singh 2017-03-17 7:17 ` John Hubbard 2017-03-17 7:17 ` John Hubbard 2017-03-16 16:05 ` [HMM 08/16] mm/migrate: migrate_vma() unmap page from vma while collecting pages Jérôme Glisse 2017-03-16 16:05 ` Jérôme Glisse 2017-03-16 16:05 ` [HMM 09/16] mm/hmm: heterogeneous memory management (HMM for short) Jérôme Glisse 2017-03-16 16:05 ` Jérôme Glisse 2017-03-19 20:09 ` Mel Gorman 2017-03-19 20:09 ` Mel Gorman 2017-03-16 16:05 ` [HMM 10/16] mm/hmm/mirror: mirror process address space on device with HMM helpers Jérôme Glisse 2017-03-16 16:05 ` Jérôme Glisse 2017-03-19 20:09 ` Mel Gorman 2017-03-19 20:09 ` Mel Gorman 2017-03-16 16:05 ` [HMM 11/16] mm/hmm/mirror: helper to snapshot CPU page table v2 Jérôme Glisse 2017-03-16 16:05 ` Jérôme Glisse 2017-03-19 20:09 ` Mel Gorman 2017-03-19 20:09 ` Mel Gorman 2017-03-16 16:05 ` [HMM 12/16] mm/hmm/mirror: device page fault handler Jérôme Glisse 2017-03-16 16:05 ` Jérôme Glisse 2017-03-16 16:05 ` [HMM 13/16] mm/hmm/migrate: support un-addressable ZONE_DEVICE page in migration Jérôme Glisse 2017-03-16 16:05 ` Jérôme Glisse 2017-03-16 16:05 ` [HMM 14/16] mm/migrate: allow migrate_vma() to alloc new page on empty entry Jérôme Glisse 2017-03-16 16:05 ` Jérôme Glisse 2017-03-16 16:05 ` [HMM 15/16] mm/hmm/devmem: device memory hotplug using ZONE_DEVICE Jérôme Glisse 2017-03-16 16:05 ` Jérôme Glisse 2017-03-16 16:05 ` [HMM 16/16] mm/hmm/devmem: dummy HMM device for ZONE_DEVICE memory v2 Jérôme Glisse 2017-03-16 16:05 ` Jérôme Glisse 2017-03-17 6:55 ` Bob Liu 2017-03-17 6:55 ` Bob Liu 2017-03-17 16:53 ` Jerome Glisse 2017-03-17 16:53 ` Jerome Glisse 2017-03-16 20:43 ` [HMM 00/16] HMM (Heterogeneous Memory Management) v18 Andrew Morton 2017-03-16 20:43 ` Andrew Morton 2017-03-16 23:49 ` Jerome Glisse 2017-03-16 23:49 ` Jerome Glisse 2017-03-17 8:29 ` Bob Liu 2017-03-17 8:29 ` Bob Liu 2017-03-17 15:57 ` Jerome Glisse 2017-03-17 15:57 ` Jerome Glisse 2017-03-17 8:39 ` Bob Liu 2017-03-17 8:39 ` Bob Liu 2017-03-17 15:52 ` Jerome Glisse 2017-03-17 15:52 ` Jerome Glisse 2017-03-19 20:09 ` Mel Gorman 2017-03-19 20:09 ` Mel Gorman
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