* Yajun Deng <yajun.deng@xxxxxxxxx> [240124 22:50]:
> We need to find the current vma by find_vma_intersection() in
> vma_merge(). Since the src vma was passed, we can add a check to figure
> out if the current vma is NULL or the src vma directly.
>
> Remove find_vma_intersection() in vma_merge(). And initialize the next to
> NULL when defining it.
>
> Signed-off-by: Yajun Deng <yajun.deng@xxxxxxxxx>
Reviewed-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
> ---
> mm/mmap.c | 15 +++++++++------
> 1 file changed, 9 insertions(+), 6 deletions(-)
>
> diff --git a/mm/mmap.c b/mm/mmap.c
> index f19bc53bc08e..ea02fdc91aa2 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -869,7 +869,7 @@ static struct vm_area_struct
> struct mm_struct *mm = src->vm_mm;
> struct anon_vma *anon_vma = src->anon_vma;
> struct file *file = src->vm_file;
> - struct vm_area_struct *curr, *next, *res;
> + struct vm_area_struct *curr = src, *next = NULL, *res;
> struct vm_area_struct *vma, *adjust, *remove, *remove2;
> struct vm_area_struct *anon_dup = NULL;
> struct vma_prepare vp;
> @@ -890,14 +890,18 @@ static struct vm_area_struct
> if (vm_flags & VM_SPECIAL)
> return NULL;
>
> - /* Does the input range span an existing VMA? (cases 5 - 8) */
> - curr = find_vma_intersection(mm, prev ? prev->vm_end : 0, end);
> + /*
> + * If the current vma and the prev vma are the same vma, it
> + * means the current vma is NULL.
> + * Does the input range span an existing VMA? (cases 5 - 8)
> + */
> + if (prev == curr || addr != curr->vm_start || end > curr->vm_end)
> + curr = NULL;
>
> if (!curr || /* cases 1 - 4 */
> end == curr->vm_end) /* cases 6 - 8, adjacent VMA */
> next = vma_lookup(mm, end);
> - else
> - next = NULL; /* case 5 */
> + /* case 5 set to NULL above */
>
> if (prev) {
> vma_start = prev->vm_start;
> @@ -921,7 +925,6 @@ static struct vm_area_struct
>
> /* Verify some invariant that must be enforced by the caller. */
> VM_WARN_ON(prev && addr <= prev->vm_start);
> - VM_WARN_ON(curr && (addr != curr->vm_start || end > curr->vm_end));
> VM_WARN_ON(addr >= end);
>
> if (!merge_prev && !merge_next)
> --
> 2.25.1
>
