From: Gonzalo Matias Juarez Tello <gmjuareztello@xxxxxxxxx> Subject: mm/mmap.c: logic of find_vma_intersection repeated in __do_munmap Logic of find_vma_intersection() is repeated in __do_munmap(). Also, prev is assigned a value before checking vma->vm_start >= end which might end up on a return statement making that assignment useless. Calling find_vma_intersection() checks that condition and returns NULL if no vma is found, hence only the !vma check is needed in __do_munmap(). Link: https://lkml.kernel.org/r/20210409162129.18313-1-gmjuareztello@xxxxxxxxx Signed-off-by: Gonzalo Matias Juarez Tello <gmjuareztello@xxxxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/mmap.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) --- a/mm/mmap.c~mm-mmapc-logic-of-find_vma_intersection-repeated-in-__do_munmap +++ a/mm/mmap.c @@ -2828,16 +2828,11 @@ int __do_munmap(struct mm_struct *mm, un */ arch_unmap(mm, start, end); - /* Find the first overlapping VMA */ - vma = find_vma(mm, start); + /* Find the first overlapping VMA where start < vma->vm_end */ + vma = find_vma_intersection(mm, start, end); if (!vma) return 0; prev = vma->vm_prev; - /* we have start < vma->vm_end */ - - /* if it doesn't overlap, we have nothing.. */ - if (vma->vm_start >= end) - return 0; /* * If we need to split any vma, do it now to save pain later. _
