From: "Liam R. Howlett" Liam.Howlett@oracle.com
based on commit 0503ea8f5ba73eb3ab13a81c1eefbaf51405385a upstream.
This was inadvertently fixed during the removal of __vma_adjust().
When __vma_adjust() is adjusting next with a negative value (pushing vma->vm_end lower), there would be two writes to the maple tree. The first write is unnecessary and uses all allocated nodes in the maple state. The second write is necessary but will need to allocate nodes since the first write has used the allocated nodes. This may be a problem as it may not be safe to allocate at this time, such as a low memory situation. Fix the issue by avoiding the first write and only write the adjusted "next" VMA.
Reported-by: John Hsu John.Hsu@mediatek.com Link: https://lore.kernel.org/lkml/9cb8c599b1d7f9c1c300d1a334d5eb70ec4d7357.camel@... Cc: stable@vger.kernel.org Cc: linux-mm@kvack.org Signed-off-by: Liam R. Howlett Liam.Howlett@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/mmap.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/mm/mmap.c +++ b/mm/mmap.c @@ -767,7 +767,8 @@ int __vma_adjust(struct vm_area_struct * } if (end != vma->vm_end) { if (vma->vm_end > end) { - if (!insert || (insert->vm_start != end)) { + if ((vma->vm_end + adjust_next != end) && + (!insert || (insert->vm_start != end))) { vma_mas_szero(&mas, end, vma->vm_end); mas_reset(&mas); VM_WARN_ON(insert &&