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![Linus Torvalds](/assets/img/avatar_default.png)
Merge emailed patches from Peter Xu:
"This is a small series that I picked up from Linus's suggestion to
simplify cow handling (and also make it more strict) by checking
against page refcounts rather than mapcounts.
This makes uffd-wp work again (verified by running upmapsort)"
Note: this is horrendously bad timing, and making this kind of
fundamental vm change after -rc3 is not at all how things should work.
The saving grace is that it really is a a nice simplification:
8 files changed, 29 insertions(+), 120 deletions(-)
The reason for the bad timing is that it turns out that commit
17839856fd
("gup: document and work around 'COW can break either way'
issue" broke not just UFFD functionality (as Peter noticed), but Mikulas
Patocka also reports that it caused issues for strace when running in a
DAX environment with ext4 on a persistent memory setup.
And we can't just revert that commit without re-introducing the original
issue that is a potential security hole, so making COW stricter (and in
the process much simpler) is a step to then undoing the forced COW that
broke other uses.
Link: https://lore.kernel.org/lkml/alpine.LRH.2.02.2009031328040.6929@file01.intranet.prod.int.rdu2.redhat.com/
* emailed patches from Peter Xu <peterx@redhat.com>:
mm: Add PGREUSE counter
mm/gup: Remove enfornced COW mechanism
mm/ksm: Remove reuse_ksm_page()
mm: do_wp_page() simplification
134 lines
3.3 KiB
C
134 lines
3.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef VM_EVENT_ITEM_H_INCLUDED
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#define VM_EVENT_ITEM_H_INCLUDED
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#ifdef CONFIG_ZONE_DMA
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#define DMA_ZONE(xx) xx##_DMA,
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#else
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#define DMA_ZONE(xx)
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#endif
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#ifdef CONFIG_ZONE_DMA32
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#define DMA32_ZONE(xx) xx##_DMA32,
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#else
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#define DMA32_ZONE(xx)
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#endif
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#ifdef CONFIG_HIGHMEM
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#define HIGHMEM_ZONE(xx) xx##_HIGH,
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#else
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#define HIGHMEM_ZONE(xx)
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#endif
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#define FOR_ALL_ZONES(xx) DMA_ZONE(xx) DMA32_ZONE(xx) xx##_NORMAL, HIGHMEM_ZONE(xx) xx##_MOVABLE
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enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
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FOR_ALL_ZONES(PGALLOC),
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FOR_ALL_ZONES(ALLOCSTALL),
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FOR_ALL_ZONES(PGSCAN_SKIP),
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PGFREE, PGACTIVATE, PGDEACTIVATE, PGLAZYFREE,
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PGFAULT, PGMAJFAULT,
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PGLAZYFREED,
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PGREFILL,
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PGREUSE,
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PGSTEAL_KSWAPD,
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PGSTEAL_DIRECT,
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PGSCAN_KSWAPD,
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PGSCAN_DIRECT,
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PGSCAN_DIRECT_THROTTLE,
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PGSCAN_ANON,
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PGSCAN_FILE,
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PGSTEAL_ANON,
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PGSTEAL_FILE,
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#ifdef CONFIG_NUMA
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PGSCAN_ZONE_RECLAIM_FAILED,
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#endif
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PGINODESTEAL, SLABS_SCANNED, KSWAPD_INODESTEAL,
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KSWAPD_LOW_WMARK_HIT_QUICKLY, KSWAPD_HIGH_WMARK_HIT_QUICKLY,
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PAGEOUTRUN, PGROTATED,
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DROP_PAGECACHE, DROP_SLAB,
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OOM_KILL,
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#ifdef CONFIG_NUMA_BALANCING
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NUMA_PTE_UPDATES,
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NUMA_HUGE_PTE_UPDATES,
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NUMA_HINT_FAULTS,
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NUMA_HINT_FAULTS_LOCAL,
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NUMA_PAGE_MIGRATE,
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#endif
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#ifdef CONFIG_MIGRATION
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PGMIGRATE_SUCCESS, PGMIGRATE_FAIL,
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THP_MIGRATION_SUCCESS,
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THP_MIGRATION_FAIL,
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THP_MIGRATION_SPLIT,
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#endif
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#ifdef CONFIG_COMPACTION
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COMPACTMIGRATE_SCANNED, COMPACTFREE_SCANNED,
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COMPACTISOLATED,
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COMPACTSTALL, COMPACTFAIL, COMPACTSUCCESS,
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KCOMPACTD_WAKE,
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KCOMPACTD_MIGRATE_SCANNED, KCOMPACTD_FREE_SCANNED,
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#endif
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#ifdef CONFIG_HUGETLB_PAGE
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HTLB_BUDDY_PGALLOC, HTLB_BUDDY_PGALLOC_FAIL,
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#endif
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UNEVICTABLE_PGCULLED, /* culled to noreclaim list */
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UNEVICTABLE_PGSCANNED, /* scanned for reclaimability */
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UNEVICTABLE_PGRESCUED, /* rescued from noreclaim list */
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UNEVICTABLE_PGMLOCKED,
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UNEVICTABLE_PGMUNLOCKED,
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UNEVICTABLE_PGCLEARED, /* on COW, page truncate */
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UNEVICTABLE_PGSTRANDED, /* unable to isolate on unlock */
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE
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THP_FAULT_ALLOC,
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THP_FAULT_FALLBACK,
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THP_FAULT_FALLBACK_CHARGE,
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THP_COLLAPSE_ALLOC,
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THP_COLLAPSE_ALLOC_FAILED,
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THP_FILE_ALLOC,
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THP_FILE_FALLBACK,
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THP_FILE_FALLBACK_CHARGE,
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THP_FILE_MAPPED,
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THP_SPLIT_PAGE,
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THP_SPLIT_PAGE_FAILED,
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THP_DEFERRED_SPLIT_PAGE,
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THP_SPLIT_PMD,
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#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
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THP_SPLIT_PUD,
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#endif
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THP_ZERO_PAGE_ALLOC,
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THP_ZERO_PAGE_ALLOC_FAILED,
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THP_SWPOUT,
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THP_SWPOUT_FALLBACK,
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#endif
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#ifdef CONFIG_MEMORY_BALLOON
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BALLOON_INFLATE,
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BALLOON_DEFLATE,
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#ifdef CONFIG_BALLOON_COMPACTION
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BALLOON_MIGRATE,
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#endif
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#endif
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#ifdef CONFIG_DEBUG_TLBFLUSH
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NR_TLB_REMOTE_FLUSH, /* cpu tried to flush others' tlbs */
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NR_TLB_REMOTE_FLUSH_RECEIVED,/* cpu received ipi for flush */
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NR_TLB_LOCAL_FLUSH_ALL,
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NR_TLB_LOCAL_FLUSH_ONE,
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#endif /* CONFIG_DEBUG_TLBFLUSH */
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#ifdef CONFIG_DEBUG_VM_VMACACHE
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VMACACHE_FIND_CALLS,
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VMACACHE_FIND_HITS,
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#endif
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#ifdef CONFIG_SWAP
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SWAP_RA,
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SWAP_RA_HIT,
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#endif
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NR_VM_EVENT_ITEMS
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};
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#ifndef CONFIG_TRANSPARENT_HUGEPAGE
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#define THP_FILE_ALLOC ({ BUILD_BUG(); 0; })
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#define THP_FILE_FALLBACK ({ BUILD_BUG(); 0; })
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#define THP_FILE_FALLBACK_CHARGE ({ BUILD_BUG(); 0; })
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#define THP_FILE_MAPPED ({ BUILD_BUG(); 0; })
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#endif
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#endif /* VM_EVENT_ITEM_H_INCLUDED */
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