kernel/linux.git/mm/compaction.c, branch v6.6.131

NFS: fix nfs_release_folio() to not deadlock via kcompactd writeback

2025-03-13T11:58:27+00:00

commit ce6d9c1c2b5cc785016faa11b48b6cd317eb367e upstream. Add PF_KCOMPACTD flag and current_is_kcompactd() helper to check for it so nfs_release_folio() can skip calling nfs_wb_folio() from kcompactd. Otherwise NFS can deadlock waiting for kcompactd enduced writeback which recurses back to NFS (which triggers writeback to NFSD via NFS loopback mount on the same host, NFSD blocks waiting for XFS's call to __filemap_get_folio): 6070.550357] INFO: task kcompactd0:58 blocked for more than 4435 seconds. {--- [58] "kcompactd0" [<0>] folio_wait_bit+0xe8/0x200 [<0>] folio_wait_writeback+0x2b/0x80 [<0>] nfs_wb_folio+0x80/0x1b0 [nfs] [<0>] nfs_release_folio+0x68/0x130 [nfs] [<0>] split_huge_page_to_list_to_order+0x362/0x840 [<0>] migrate_pages_batch+0x43d/0xb90 [<0>] migrate_pages_sync+0x9a/0x240 [<0>] migrate_pages+0x93c/0x9f0 [<0>] compact_zone+0x8e2/0x1030 [<0>] compact_node+0xdb/0x120 [<0>] kcompactd+0x121/0x2e0 [<0>] kthread+0xcf/0x100 [<0>] ret_from_fork+0x31/0x40 [<0>] ret_from_fork_asm+0x1a/0x30 ---} [akpm@linux-foundation.org: fix build] Link: https://lkml.kernel.org/r/20250225022002.26141-1-snitzer@kernel.org Fixes: 96780ca55e3c ("NFS: fix up nfs_release_folio() to try to release the page") Signed-off-by: Mike Snitzer Cc: Anna Schumaker Cc: Trond Myklebust Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

mm, treewide: introduce NR_PAGE_ORDERS

2024-05-02T14:32:41+00:00

[ Upstream commit fd37721803c6e73619108f76ad2e12a9aa5fafaf ] NR_PAGE_ORDERS defines the number of page orders supported by the page allocator, ranging from 0 to MAX_ORDER, MAX_ORDER + 1 in total. NR_PAGE_ORDERS assists in defining arrays of page orders and allows for more natural iteration over them. [kirill.shutemov@linux.intel.com: fixup for kerneldoc warning] Link: https://lkml.kernel.org/r/20240101111512.7empzyifq7kxtzk3@box Link: https://lkml.kernel.org/r/20231228144704.14033-1-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov Reviewed-by: Zi Yan Cc: Linus Torvalds Signed-off-by: Andrew Morton Stable-dep-of: b6976f323a86 ("drm/ttm: stop pooling cached NUMA pages v2") Signed-off-by: Sasha Levin

mm, vmscan: prevent infinite loop for costly GFP_NOIO | __GFP_RETRY_MAYFAIL allocations

2024-04-03T13:28:44+00:00

commit 803de9000f334b771afacb6ff3e78622916668b0 upstream. Sven reports an infinite loop in __alloc_pages_slowpath() for costly order __GFP_RETRY_MAYFAIL allocations that are also GFP_NOIO. Such combination can happen in a suspend/resume context where a GFP_KERNEL allocation can have __GFP_IO masked out via gfp_allowed_mask. Quoting Sven: 1. try to do a "costly" allocation (order > PAGE_ALLOC_COSTLY_ORDER) with __GFP_RETRY_MAYFAIL set. 2. page alloc's __alloc_pages_slowpath tries to get a page from the freelist. This fails because there is nothing free of that costly order. 3. page alloc tries to reclaim by calling __alloc_pages_direct_reclaim, which bails out because a zone is ready to be compacted; it pretends to have made a single page of progress. 4. page alloc tries to compact, but this always bails out early because __GFP_IO is not set (it's not passed by the snd allocator, and even if it were, we are suspending so the __GFP_IO flag would be cleared anyway). 5. page alloc believes reclaim progress was made (because of the pretense in item 3) and so it checks whether it should retry compaction. The compaction retry logic thinks it should try again, because: a) reclaim is needed because of the early bail-out in item 4 b) a zonelist is suitable for compaction 6. goto 2. indefinite stall. (end quote) The immediate root cause is confusing the COMPACT_SKIPPED returned from __alloc_pages_direct_compact() (step 4) due to lack of __GFP_IO to be indicating a lack of order-0 pages, and in step 5 evaluating that in should_compact_retry() as a reason to retry, before incrementing and limiting the number of retries. There are however other places that wrongly assume that compaction can happen while we lack __GFP_IO. To fix this, introduce gfp_compaction_allowed() to abstract the __GFP_IO evaluation and switch the open-coded test in try_to_compact_pages() to use it. Also use the new helper in: - compaction_ready(), which will make reclaim not bail out in step 3, so there's at least one attempt to actually reclaim, even if chances are small for a costly order - in_reclaim_compaction() which will make should_continue_reclaim() return false and we don't over-reclaim unnecessarily - in __alloc_pages_slowpath() to set a local variable can_compact, which is then used to avoid retrying reclaim/compaction for costly allocations (step 5) if we can't compact and also to skip the early compaction attempt that we do in some cases Link: https://lkml.kernel.org/r/20240221114357.13655-2-vbabka@suse.cz Fixes: 3250845d0526 ("Revert "mm, oom: prevent premature OOM killer invocation for high order request"") Signed-off-by: Vlastimil Babka Reported-by: Sven van Ashbrook Closes: https://lore.kernel.org/all/CAG-rBihs_xMKb3wrMO1%2B-%2Bp4fowP9oy1pa_OTkfxBzPUVOZF%2Bg@mail.gmail.com/ Tested-by: Karthikeyan Ramasubramanian Cc: Brian Geffon Cc: Curtis Malainey Cc: Jaroslav Kysela Cc: Mel Gorman Cc: Michal Hocko Cc: Takashi Iwai Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

merge mm-hotfixes-stable into mm-stable to pick up depended-upon changes

2023-08-21T21:26:20+00:00

mm/compaction: remove unused parameter pgdata of fragmentation_score_wmark

2023-08-21T20:37:50+00:00

Parameter pgdat is not used in fragmentation_score_wmark. Just remove it. Link: https://lkml.kernel.org/r/20230809094910.3092446-1-shikemeng@huaweicloud.com Signed-off-by: Kemeng Shi Reviewed-by: David Hildenbrand Acked-by: Mel Gorman Reviewed-by: Baolin Wang Cc: Matthew Wilcox Signed-off-by: Andrew Morton

mm/compaction: only set skip flag if cc->no_set_skip_hint is false

2023-08-21T20:37:43+00:00

Keep the same logic as update_pageblock_skip, only set skip if no_set_skip_hint is false which is more reasonable. Link: https://lkml.kernel.org/r/20230804110454.2935878-9-shikemeng@huaweicloud.com Signed-off-by: Kemeng Shi Reviewed-by: David Hildenbrand Cc: Baolin Wang Cc: Mel Gorman Signed-off-by: Andrew Morton

mm/compaction: remove unnecessary return for void function

2023-08-21T20:37:43+00:00

Remove unnecessary return for void function Link: https://lkml.kernel.org/r/20230804110454.2935878-8-shikemeng@huaweicloud.com Signed-off-by: Kemeng Shi Reviewed-by: David Hildenbrand Reviewed-by: Baolin Wang Cc: Mel Gorman Signed-off-by: Andrew Morton

mm/compaction: correct comment to complete migration failure

2023-08-21T20:37:43+00:00

Commit cfccd2e63e7e0 ("mm, compaction: finish pageblocks on complete migration failure") convert cc->order aligned check to page block order aligned check. Correct comment relevant with it. Link: https://lkml.kernel.org/r/20230804110454.2935878-7-shikemeng@huaweicloud.com Signed-off-by: Kemeng Shi Cc: Baolin Wang Cc: David Hildenbrand Cc: Mel Gorman Signed-off-by: Andrew Morton

mm/compaction: correct comment of cached migrate pfn update

2023-08-21T20:37:42+00:00

Commit e380bebe47715 ("mm, compaction: keep migration source private to a single compaction instance") moved update of async and sync compact_cached_migrate_pfn from update_pageblock_skip to update_cached_migrate but left the comment behind. Move the relevant comment to correct this. Link: https://lkml.kernel.org/r/20230804110454.2935878-6-shikemeng@huaweicloud.com Signed-off-by: Kemeng Shi Reviewed-by: David Hildenbrand Reviewed-by: Baolin Wang Cc: Mel Gorman Signed-off-by: Andrew Morton

mm/compaction: correct comment of fast_find_migrateblock in isolate_migratepages

2023-08-21T20:37:42+00:00

After 90ed667c03fe5 ("Revert "Revert "mm/compaction: fix set skip in fast_find_migrateblock"""), we remove skip set in fast_find_migrateblock. Correct comment that fast_find_block is used to avoid isolation_suitable check for pageblock returned from fast_find_migrateblock because fast_find_migrateblock will mark found pageblock skipped. Instead, comment that fast_find_block is used to avoid a redundant check of fast found pageblock which is already checked skip flag inside fast_find_migrateblock. Link: https://lkml.kernel.org/r/20230804110454.2935878-5-shikemeng@huaweicloud.com Signed-off-by: Kemeng Shi Reviewed-by: Baolin Wang Cc: David Hildenbrand Cc: Mel Gorman Signed-off-by: Andrew Morton