From 00cd00a6a2b1cc0b7d35e56444dab96879def809 Mon Sep 17 00:00:00 2001 From: Lorenzo Stoakes Date: Wed, 22 Mar 2023 20:18:58 +0000 Subject: mm/mmap/vma_merge: fold curr, next assignment logic Use find_vma_intersection() and vma_lookup() to both simplify the logic and to fold the end == next->vm_start condition into one block. This groups all of the simple range checks together and establishes the invariant that, if prev, curr or next are non-NULL then their positions are as expected. This has no functional impact. Link: https://lkml.kernel.org/r/c6d960641b4ba58fa6ad3d07bf68c27d847963c8.1679516210.git.lstoakes@gmail.com Signed-off-by: Lorenzo Stoakes Reviewed-by: Vlastimil Babka Reviewed-by: Liam R. Howlett Cc: David Hildenbrand Cc: Matthew Wilcox (Oracle) Cc: Vernon Yang Signed-off-by: Andrew Morton --- mm/mmap.c | 24 +++++++++++------------- 1 file changed, 11 insertions(+), 13 deletions(-) (limited to 'mm/mmap.c') diff --git a/mm/mmap.c b/mm/mmap.c index 030715027249..e2e2c970374a 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -917,15 +917,14 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, if (vm_flags & VM_SPECIAL) return NULL; - curr = find_vma(mm, prev ? prev->vm_end : 0); - if (curr && curr->vm_end == end) /* cases 6, 7, 8 */ - next = find_vma(mm, curr->vm_end); - else - next = curr; + /* Does the input range span an existing VMA? (cases 5 - 8) */ + curr = find_vma_intersection(mm, prev ? prev->vm_end : 0, end); - /* In cases 1 - 4 there's no CCCC vma */ - if (curr && end <= curr->vm_start) - 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 */ /* verify some invariant that must be enforced by the caller */ VM_WARN_ON(prev && addr <= prev->vm_start); @@ -946,11 +945,10 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, } } /* Can we merge the successor? */ - if (next && end == next->vm_start && - mpol_equal(policy, vma_policy(next)) && - can_vma_merge_before(next, vm_flags, - anon_vma, file, pgoff+pglen, - vm_userfaultfd_ctx, anon_name)) { + if (next && mpol_equal(policy, vma_policy(next)) && + can_vma_merge_before(next, vm_flags, + anon_vma, file, pgoff+pglen, + vm_userfaultfd_ctx, anon_name)) { merge_next = true; } -- cgit