| Date | Wed, 15 Feb 2023 21:17:36 -0800 | Subject | [PATCH v3 21/35] mm/mmap: write-lock adjacent VMAs if they can grow into unmapped area | From | Suren Baghdasaryan <> |
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While unmapping VMAs, adjacent VMAs might be able to grow into the area being unmapped. In such cases write-lock adjacent VMAs to prevent this growth.
Signed-off-by: Suren Baghdasaryan <surenb@google.com> --- mm/mmap.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/mm/mmap.c b/mm/mmap.c index 118b2246bba9..00f8c5798936 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2399,11 +2399,13 @@ do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma, * down_read(mmap_lock) and collide with the VMA we are about to unmap. */ if (downgrade) { - if (next && (next->vm_flags & VM_GROWSDOWN)) + if (next && (next->vm_flags & VM_GROWSDOWN)) { + vma_start_write(next); downgrade = false; - else if (prev && (prev->vm_flags & VM_GROWSUP)) + } else if (prev && (prev->vm_flags & VM_GROWSUP)) { + vma_start_write(prev); downgrade = false; - else + } else mmap_write_downgrade(mm); } -- 2.39.1
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