If the prev vma exists and the end is less than the end of prev, we can return NULL immediately. This reduces unnecessary operations. Signed-off-by: Yajun Deng <yajun.deng@xxxxxxxxx> --- mm/mmap.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/mmap.c b/mm/mmap.c index 8f176027583c..b738849321c0 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -827,7 +827,7 @@ can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, * * **** **** **** * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPCCCCCC - * cannot merge might become might become + * cannot merge 9 might become might become * PPNNNNNNNNNN PPPPPPPPPPCC * mmap, brk or case 4 below case 5 below * mremap move: @@ -890,6 +890,9 @@ static struct vm_area_struct if (vm_flags & VM_SPECIAL) return NULL; + if (prev && end < prev->vm_end) /* case 9 */ + return NULL; + /* Does the input range span an existing VMA? (cases 5 - 8) */ curr = find_vma_intersection(mm, prev ? prev->vm_end : 0, end); -- 2.25.1
