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| author | Kiryl Shutsemau (Meta) <kas@kernel.org> | 2026-07-08 12:14:12 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-07-26 22:49:18 -0700 |
| commit | 84a956c1b15071b222305b561b38a2abcf07e9a9 (patch) | |
| tree | 04bc7cd9b6db8d04c8f81a137e6c8c8806a6ff67 /tools/include | |
| parent | bd1397efbf7662b164155f6a3305036663ce6e25 (diff) | |
| download | linux-next-84a956c1b15071b222305b561b38a2abcf07e9a9.tar.gz linux-next-84a956c1b15071b222305b561b38a2abcf07e9a9.zip | |
mm/pagemap: add PAGE_IS_ACCESSED for RWP tracking
PAGEMAP_SCAN already reports PAGE_IS_WRITTEN from the inverted uffd PTE
bit, targeting the UFFDIO_WRITEPROTECT workflow. UFFDIO_RWPROTECT reuses
the same PTE bit as a marker for read-write protection, but "has been
written" and "has been accessed" are distinct semantic signals — they
happen to share one PTE bit today only because the two implementations
share infrastructure.
Give RWP its own pagemap category so the UAPI does not conflate them:
PAGE_IS_WRITTEN reported on VM_UFFD_WP VMAs, !pte_uffd(pte)
PAGE_IS_ACCESSED reported on VM_UFFD_RWP VMAs, !pte_uffd(pte)
Both still read the same PTE bit today, but each is scoped to the VMA
whose registered mode makes the bit meaningful. If a future
implementation moves RWP to a separate PTE bit, only PAGE_IS_ACCESSED
switches over.
This is a UAPI narrowing. Outside VM_UFFD_WP VMAs the uffd bit is always
clear, so PAGEMAP_SCAN used to flag PAGE_IS_WRITTEN on every present PTE
there — a meaningless duplicate of PAGE_IS_PRESENT. Now PAGE_IS_WRITTEN
fires only inside VM_UFFD_WP VMAs.
pagemap_hugetlb_category() now takes the vma like its PTE/PMD peers.
Link: https://lore.kernel.org/20260708111417.173443-12-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
Assisted-by: Claude:claude-opus-4-6
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: James Houghton <jthoughton@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'tools/include')
| -rw-r--r-- | tools/include/uapi/linux/fs.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/tools/include/uapi/linux/fs.h b/tools/include/uapi/linux/fs.h index 24ddf7bc4f25..f0a26309b6d5 100644 --- a/tools/include/uapi/linux/fs.h +++ b/tools/include/uapi/linux/fs.h @@ -364,6 +364,7 @@ typedef int __bitwise __kernel_rwf_t; #define PAGE_IS_HUGE (1 << 6) #define PAGE_IS_SOFT_DIRTY (1 << 7) #define PAGE_IS_GUARD (1 << 8) +#define PAGE_IS_ACCESSED (1 << 9) /* * struct page_region - Page region with flags |