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| author | Kiryl Shutsemau (Meta) <kas@kernel.org> | 2026-07-08 12:14:07 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-08-04 19:18:37 -0700 |
| commit | 9cf3c554acbdd3661e2ae5043de842a551c5d0ed (patch) | |
| tree | 529c99899da9b76081201572425deb45aeea7196 /include | |
| parent | 134c1d031a2e9d2f6a3f56fc358df8df7ffeef2b (diff) | |
| download | linux-next-9cf3c554acbdd3661e2ae5043de842a551c5d0ed.tar.gz linux-next-9cf3c554acbdd3661e2ae5043de842a551c5d0ed.zip | |
mm: add MM_CP_UFFD_RWP change_protection() flag
Preparatory patch. Add the change_protection() primitive that userfaultfd
RWP will use.
An RWP-protected PTE is PAGE_NONE with the uffd PTE bit set. The
PROT_NONE half makes the CPU fault on any access; the uffd bit
distinguishes an RWP fault from a plain mprotect(PROT_NONE) or NUMA
hinting fault. MM_CP_UFFD_WP and MM_CP_UFFD_RWP share the same PTE bit,
so the two cannot be used together on the same range.
Two new change_protection() flags:
MM_CP_UFFD_RWP install PAGE_NONE and set the uffd bit
MM_CP_UFFD_RWP_RESOLVE restore vma->vm_page_prot, clear the uffd bit
Both are wired through change_pte_range(), change_huge_pmd(), and
hugetlb_change_protection() so anon, shmem, THP, and hugetlb all share the
same semantics.
Link: https://lore.kernel.org/20260708111417.173443-7-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
Assisted-by: Claude:claude-opus-4-6
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: SeongJae Park <sj@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@infradead.org>
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: 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 'include')
| -rw-r--r-- | include/linux/mm.h | 5 | ||||
| -rw-r--r-- | include/linux/userfaultfd_k.h | 1 |
2 files changed, 5 insertions, 1 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index 61bcd65cd029..170f21f28c77 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -3340,6 +3340,11 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen); #define MM_CP_UFFD_WP_RESOLVE (1UL << 3) /* Resolve wp */ #define MM_CP_UFFD_WP_ALL (MM_CP_UFFD_WP | \ MM_CP_UFFD_WP_RESOLVE) +/* Whether this change is for uffd RWP */ +#define MM_CP_UFFD_RWP (1UL << 4) /* do rwp */ +#define MM_CP_UFFD_RWP_RESOLVE (1UL << 5) /* resolve rwp */ +#define MM_CP_UFFD_RWP_ALL (MM_CP_UFFD_RWP | \ + MM_CP_UFFD_RWP_RESOLVE) bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr, pte_t pte); diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h index 6dad14b9abb9..0a0763c6e9f4 100644 --- a/include/linux/userfaultfd_k.h +++ b/include/linux/userfaultfd_k.h @@ -369,7 +369,6 @@ static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma, return false; } - static inline bool userfaultfd_armed(struct vm_area_struct *vma) { return false; |