From a5f434e35ef237a39cbcd47181fe329dd5e35a4b Mon Sep 17 00:00:00 2001 From: Suren Baghdasaryan Date: Thu, 7 Jul 2022 16:16:34 -0700 Subject: [PATCH] mm/mmap: write-lock adjacent VMAs if they can grow into unmapped area 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 --- mm/mmap.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index e320b6ae2cf69..7ca2632556e05 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2462,11 +2462,13 @@ do_mas_align_munmap(struct ma_state *mas, 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_write_lock(next); downgrade = false; - else if (prev && (prev->vm_flags & VM_GROWSUP)) + } else if (prev && (prev->vm_flags & VM_GROWSUP)) { + vma_write_lock(prev); downgrade = false; - else + } else mmap_write_downgrade(mm); } -- 2.50.1