kernel.git/mm/page_isolation.c, branch linux-5.19.y

mm/page_isolation: fix isolate_single_pageblock() isolation behavior

2022-10-05T08:40:46Z

commit 80e2b584f3abfc31c3fe5573007f0d1d10810fde upstream. set_migratetype_isolate() does not allow isolating MIGRATE_CMA pageblocks unless it is used for CMA allocation. isolate_single_pageblock() did not have the same behavior when it is used together with set_migratetype_isolate() in start_isolate_page_range(). This allows alloc_contig_range() with migratetype other than MIGRATE_CMA, like MIGRATE_MOVABLE (used by alloc_contig_pages()), to isolate first and last pageblock but fail the rest. The failure leads to changing migratetype of the first and last pageblock to MIGRATE_MOVABLE from MIGRATE_CMA, corrupting the CMA region. This can happen during gigantic page allocations. Like Doug said here: https://lore.kernel.org/linux-mm/a3363a52-883b-dcd1-b77f-f2bb378d6f2d@gmail.com/T/#u, for gigantic page allocations, the user would notice no difference, since the allocation on CMA region will fail as well as it did before. But it might hurt the performance of device drivers that use CMA, since CMA region size decreases. Fix it by passing migratetype into isolate_single_pageblock(), so that set_migratetype_isolate() used by isolate_single_pageblock() will prevent the isolation happening. Link: https://lkml.kernel.org/r/20220914023913.1855924-1-zi.yan@sent.com Fixes: b2c9e2fbba32 ("mm: make alloc_contig_range work at pageblock granularity") Signed-off-by: Zi Yan Reported-by: Doug Berger Cc: David Hildenbrand Cc: Doug Berger Cc: Mike Kravetz Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

mm/page_isolation.c: fix one kernel-doc comment

2022-06-17T02:11:30Z

Remove one warning found by running scripts/kernel-doc, which is caused by using 'make W=1': mm/page_isolation.c:304: warning: Function parameter or member 'skip_isolation' not described in 'isolate_single_pageblock' Link: https://lkml.kernel.org/r/20220602062116.61199-1-yang.lee@linux.alibaba.com Signed-off-by: Yang Li Reported-by: Abaci Robot Signed-off-by: Andrew Morton

mm: page_isolation: use compound_nr() correctly in isolate_single_pageblock()

2022-06-01T22:57:16Z

When compound_nr(page) was used, page was not guaranteed to be the head of the compound page and it could cause an infinite loop. Fix it by calling it on the head page. Link: https://lkml.kernel.org/r/20220531024450.2498431-1-zi.yan@sent.com Fixes: b2c9e2fbba32 ("mm: make alloc_contig_range work at pageblock granularity") Signed-off-by: Zi Yan Reported-by: Anshuman Khandual Link: https://lore.kernel.org/linux-mm/20220530115027.123341-1-anshuman.khandual@arm.com/ Reviewed-by: Anshuman Khandual Reviewed-by: Miaohe Lin Reviewed-by: Oscar Salvador Acked-by: Muchun Song Cc: David Hildenbrand Cc: Qian Cai Cc: Vlastimil Babka Cc: Mel Gorman Cc: Eric Ren Cc: Mike Rapoport Cc: Christophe Leroy Signed-off-by: Andrew Morton

mm: split free page with properly free memory accounting and without race

2022-05-27T16:33:43Z

In isolate_single_pageblock(), free pages are checked without holding zone lock, but they can go away in split_free_page() when zone lock is held. Check the free page and its order again in split_free_page() when zone lock is held. Recheck the page if the free page is gone under zone lock. In addition, in split_free_page(), the free page was deleted from the page list without changing free page accounting. Add the missing free page accounting code. Fix the type of order parameter in split_free_page(). Link: https://lore.kernel.org/lkml/20220525103621.987185e2ca0079f7b97b856d@linux-foundation.org/ Link: https://lkml.kernel.org/r/20220526231531.2404977-2-zi.yan@sent.com Fixes: b2c9e2fbba32 ("mm: make alloc_contig_range work at pageblock granularity") Signed-off-by: Zi Yan Reported-by: Doug Berger Link: https://lore.kernel.org/linux-mm/c3932a6f-77fe-29f7-0c29-fe6b1c67ab7b@gmail.com/ Cc: David Hildenbrand Cc: Qian Cai Cc: Vlastimil Babka Cc: Mel Gorman Cc: Eric Ren Cc: Mike Rapoport Cc: Oscar Salvador Cc: Christophe Leroy Cc: Marek Szyprowski Cc: Michael Walle Signed-off-by: Andrew Morton

mm: page-isolation: skip isolated pageblock in start_isolate_page_range()

2022-05-27T16:33:42Z

start_isolate_page_range() first isolates the first and the last pageblocks in the range and ensure pages across range boundaries are split during isolation. But it missed the case when the range is <= a pageblock and the first and the last pageblocks are the same one, so the second isolate_single_pageblock() will always fail. To fix it, skip the pageblock isolation in second isolate_single_pageblock(). Link: https://lkml.kernel.org/r/20220526231531.2404977-1-zi.yan@sent.com Fixes: 88ee134320b8 ("mm: fix a potential infinite loop in start_isolate_page_range()") Signed-off-by: Zi Yan Reported-by: Marek Szyprowski Tested-by: Marek Szyprowski Link: https://lore.kernel.org/linux-mm/ac65adc0-a7e4-cdfe-a0d8-757195b86293@samsung.com/ Reported-by: Michael Walle Tested-by: Michael Walle Link: https://lore.kernel.org/linux-mm/8ca048ca8b547e0dd1c95387ee05c23d@walle.cc/ Cc: Christophe Leroy Cc: David Hildenbrand Cc: Doug Berger Cc: Eric Ren Cc: Mel Gorman Cc: Mike Rapoport Cc: Oscar Salvador Cc: Qian Cai Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm: fix a potential infinite loop in start_isolate_page_range()

2022-05-25T17:47:47Z

In isolate_single_pageblock() called by start_isolate_page_range(), there are some pageblock isolation issues causing a potential infinite loop when isolating a page range. This is reported by Qian Cai. 1. the pageblock was isolated by just changing pageblock migratetype without checking unmovable pages. Calling set_migratetype_isolate() to isolate pageblock properly. 2. an off-by-one error caused migrating pages unnecessarily, since the page is not crossing pageblock boundary. 3. migrating a compound page across pageblock boundary then splitting the free page later has a small race window that the free page might be allocated again, so that the code will try again, causing an potential infinite loop. Temporarily set the to-be-migrated page's pageblock to MIGRATE_ISOLATE to prevent that and bail out early if no free page is found after page migration. An additional fix to split_free_page() aims to avoid crashing in __free_one_page(). When the free page is split at the specified split_pfn_offset, free_page_order should check both the first bit of free_page_pfn and the last bit of split_pfn_offset and use the smaller one. For example, if free_page_pfn=0x10000, split_pfn_offset=0xc000, free_page_order should first be 0x8000 then 0x4000, instead of 0x4000 then 0x8000, which the original algorithm did. [akpm@linux-foundation.org: suppress min() warning] Link: https://lkml.kernel.org/r/20220524194756.1698351-1-zi.yan@sent.com Fixes: b2c9e2fbba3253 ("mm: make alloc_contig_range work at pageblock granularity") Signed-off-by: Zi Yan Reported-by: Qian Cai Cc: Christophe Leroy Cc: David Hildenbrand Cc: Eric Ren Cc: Mel Gorman Cc: Mike Rapoport Cc: Minchan Kim Cc: Oscar Salvador Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm: page_isolation: enable arbitrary range page isolation.

2022-05-13T14:20:13Z

Now start_isolate_page_range() is ready to handle arbitrary range isolation, so move the alignment check/adjustment into the function body. Do the same for its counterpart undo_isolate_page_range(). alloc_contig_range(), its caller, can pass an arbitrary range instead of a MAX_ORDER_NR_PAGES aligned one. Link: https://lkml.kernel.org/r/20220425143118.2850746-5-zi.yan@sent.com Signed-off-by: Zi Yan Cc: Christophe Leroy Cc: David Hildenbrand Cc: Eric Ren Cc: kernel test robot Cc: Mel Gorman Cc: Mike Rapoport Cc: Minchan Kim Cc: Oscar Salvador Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm: make alloc_contig_range work at pageblock granularity

2022-05-13T14:20:13Z

alloc_contig_range() worked at MAX_ORDER_NR_PAGES granularity to avoid merging pageblocks with different migratetypes. It might unnecessarily convert extra pageblocks at the beginning and at the end of the range. Change alloc_contig_range() to work at pageblock granularity. Special handling is needed for free pages and in-use pages across the boundaries of the range specified by alloc_contig_range(). Because these= Partially isolated pages causes free page accounting issues. The free pages will be split and freed into separate migratetype lists; the in-use= Pages will be migrated then the freed pages will be handled in the aforementioned way. [ziy@nvidia.com: fix deadlock/crash] Link: https://lkml.kernel.org/r/23A7297E-6C84-4138-A9FE-3598234004E6@nvidia.com Link: https://lkml.kernel.org/r/20220425143118.2850746-4-zi.yan@sent.com Signed-off-by: Zi Yan Reported-by: kernel test robot Cc: Christophe Leroy Cc: David Hildenbrand Cc: Eric Ren Cc: Mel Gorman Cc: Mike Rapoport Cc: Minchan Kim Cc: Oscar Salvador Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm: page_isolation: check specified range for unmovable pages

2022-05-13T14:20:12Z

Enable set_migratetype_isolate() to check specified range for unmovable pages during isolation to prepare arbitrary range page isolation. The functionality will take effect in upcoming commits by adjusting the callers of start_isolate_page_range(), which uses set_migratetype_isolate(). For example, alloc_contig_range(), which calls start_isolate_page_range(), accepts unaligned ranges, but because page isolation is currently done at MAX_ORDER_NR_PAEGS granularity, pages that are out of the specified range but withint MAX_ORDER_NR_PAEGS alignment might be attempted for isolation and the failure of isolating these unrelated pages fails the whole operation undesirably. Link: https://lkml.kernel.org/r/20220425143118.2850746-3-zi.yan@sent.com Signed-off-by: Zi Yan Cc: Christophe Leroy Cc: David Hildenbrand Cc: Eric Ren Cc: kernel test robot Cc: Mel Gorman Cc: Mike Rapoport Cc: Minchan Kim Cc: Oscar Salvador Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm: page_isolation: move has_unmovable_pages() to mm/page_isolation.c

2022-05-13T14:20:12Z

Patch series "Use pageblock_order for cma and alloc_contig_range alignment", v11. This patchset tries to remove the MAX_ORDER-1 alignment requirement for CMA and alloc_contig_range(). It prepares for my upcoming changes to make MAX_ORDER adjustable at boot time[1]. The MAX_ORDER - 1 alignment requirement comes from that alloc_contig_range() isolates pageblocks to remove free memory from buddy allocator but isolating only a subset of pageblocks within a page spanning across multiple pageblocks causes free page accounting issues. Isolated page might not be put into the right free list, since the code assumes the migratetype of the first pageblock as the whole free page migratetype. This is based on the discussion at [2]. To remove the requirement, this patchset: 1. isolates pages at pageblock granularity instead of max(MAX_ORDER_NR_PAEGS, pageblock_nr_pages); 2. splits free pages across the specified range or migrates in-use pages across the specified range then splits the freed page to avoid free page accounting issues (it happens when multiple pageblocks within a single page have different migratetypes); 3. only checks unmovable pages within the range instead of MAX_ORDER - 1 aligned range during isolation to avoid alloc_contig_range() failure when pageblocks within a MAX_ORDER - 1 aligned range are allocated separately. 4. returns pages not in the range as it did before. One optimization might come later: 1. make MIGRATE_ISOLATE a separate bit to be able to restore the original migratetypes when isolation fails in the middle of the range. [1] https://lore.kernel.org/linux-mm/20210805190253.2795604-1-zi.yan@sent.com/ [2] https://lore.kernel.org/linux-mm/d19fb078-cb9b-f60f-e310-fdeea1b947d2@redhat.com/ This patch (of 6): has_unmovable_pages() is only used in mm/page_isolation.c. Move it from mm/page_alloc.c and make it static. Link: https://lkml.kernel.org/r/20220425143118.2850746-2-zi.yan@sent.com Signed-off-by: Zi Yan Reviewed-by: Oscar Salvador Reviewed-by: Mike Rapoport Acked-by: David Hildenbrand Cc: Vlastimil Babka Cc: Mel Gorman Cc: Eric Ren Cc: Christophe Leroy Cc: Minchan Kim Cc: kernel test robot Signed-off-by: Andrew Morton