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@xxxxxxxxxx>
---
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
