lkml.org 
[lkml]   [2023]   [Mar]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 03/10] mm/mmap/vma_merge: use the proper vma pointers in cases 1 and 6
    Date
    Case 1 is now shown in the comment as next vma being merged with prev,
    so use 'next' instead of 'mid'. In case 1 they both point to the same
    vma.

    As a consequence, in case 6, the dup_anon_vma() is now tried first on
    'next' and then on 'mid', before it was the opposite order. This is not
    a functional change, as those two vma's cannnot have a different
    anon_vma, as that would have prevented the merging in the first place.

    Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
    ---
    mm/mmap.c | 11 ++++++-----
    1 file changed, 6 insertions(+), 5 deletions(-)

    diff --git a/mm/mmap.c b/mm/mmap.c
    index 1af4c9bc2c87..c33237b283c9 100644
    --- a/mm/mmap.c
    +++ b/mm/mmap.c
    @@ -605,7 +605,7 @@ static inline void vma_complete(struct vma_prepare *vp,

    /*
    * In mprotect's case 6 (see comments on vma_merge),
    - * we must remove the one after next as well.
    + * we are removing both mid and next vmas
    */
    if (vp->remove2) {
    vp->remove = vp->remove2;
    @@ -948,13 +948,14 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm,
    /* Can we merge both the predecessor and the successor? */
    if (merge_prev && merge_next &&
    is_mergeable_anon_vma(prev->anon_vma, next->anon_vma, NULL)) {
    - remove = mid; /* case 1 */
    + remove = next; /* case 1 */
    vma_end = next->vm_end;
    - err = dup_anon_vma(prev, mid);
    + err = dup_anon_vma(prev, next);
    if (mid != next) { /* case 6 */
    + remove = mid;
    remove2 = next;
    - if (!mid->anon_vma)
    - err = dup_anon_vma(prev, next);
    + if (!next->anon_vma)
    + err = dup_anon_vma(prev, mid);
    }
    } else if (merge_prev) {
    err = 0; /* case 2 */
    --
    2.39.2
    \
     
     \ /
      Last update: 2023-03-27 00:51    [W:4.769 / U:0.036 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site