diff options
| author | David Hildenbrand <david@redhat.com> | 2022-12-23 16:56:16 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-01-19 02:12:50 +0100 |
| commit | 1ef488edd6c4d447784710974f049628c2890481 (patch) | |
| tree | a3577746e57294945403990ca3dd33a9a0986ee4 /mm/mprotect.c | |
| parent | mm/userfaultfd: rely on vma->vm_page_prot in uffd_wp_range() (diff) | |
| download | linux-1ef488edd6c4d447784710974f049628c2890481.tar.xz linux-1ef488edd6c4d447784710974f049628c2890481.zip | |
mm/mprotect: drop pgprot_t parameter from change_protection()
Being able to provide a custom protection opens the door for
inconsistencies and BUGs: for example, accidentally allowing for more
permissions than desired by other mechanisms (e.g., softdirty tracking).
vma->vm_page_prot should be the single source of truth.
Only PROT_NUMA is special: there is no way we can erroneously allow
for more permissions when removing all permissions. Special-case using
the MM_CP_PROT_NUMA flag.
[david@redhat.com: PAGE_NONE might not be defined without CONFIG_NUMA_BALANCING]
Link: https://lkml.kernel.org/r/5084ff1c-ebb3-f918-6a60-bacabf550a88@redhat.com
Link: https://lkml.kernel.org/r/20221223155616.297723-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/mprotect.c')
| -rw-r--r-- | mm/mprotect.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/mm/mprotect.c b/mm/mprotect.c index bf8fa0af5a15..71358e45a742 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -507,13 +507,25 @@ static unsigned long change_protection_range(struct mmu_gather *tlb, unsigned long change_protection(struct mmu_gather *tlb, struct vm_area_struct *vma, unsigned long start, - unsigned long end, pgprot_t newprot, - unsigned long cp_flags) + unsigned long end, unsigned long cp_flags) { + pgprot_t newprot = vma->vm_page_prot; unsigned long pages; BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL); +#ifdef CONFIG_NUMA_BALANCING + /* + * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking) + * are expected to reflect their requirements via VMA flags such that + * vma_set_page_prot() will adjust vma->vm_page_prot accordingly. + */ + if (cp_flags & MM_CP_PROT_NUMA) + newprot = PAGE_NONE; +#else + WARN_ON_ONCE(cp_flags & MM_CP_PROT_NUMA); +#endif + if (is_vm_hugetlb_page(vma)) pages = hugetlb_change_protection(vma, start, end, newprot, cp_flags); @@ -642,7 +654,7 @@ success: mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE; vma_set_page_prot(vma); - change_protection(tlb, vma, start, end, vma->vm_page_prot, mm_cp_flags); + change_protection(tlb, vma, start, end, mm_cp_flags); /* * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major |