The patch titled
Subject: mm/mmap/vma_merge: fold curr, next assignment logic
has been added to the -mm mm-unstable branch. Its filename is
mm-mmap-vma_merge-fold-curr-next-assignment-logic.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mmap-vma_merge-fold-curr-next-assignment-logic.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Subject: mm/mmap/vma_merge: fold curr, next assignment logic
Date: Wed, 22 Mar 2023 20:18:58 +0000
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@xxxxxxxxx
Signed-off-by: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx>
Reviewed-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Vernon Yang <vernon2gm@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/mm/mmap.c~mm-mmap-vma_merge-fold-curr-next-assignment-logic
+++ a/mm/mmap.c
@@ -930,15 +930,14 @@ struct vm_area_struct *vma_merge(struct
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);
@@ -959,11 +958,10 @@ struct vm_area_struct *vma_merge(struct
}
}
/* 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;
}
_
Patches currently in -mm which might be from lstoakes@xxxxxxxxx are
mm-prefer-xxx_page-alloc-free-functions-for-order-0-pages.patch
mm-refactor-do_fault_around.patch
mm-pefer-fault_around_pages-to-fault_around_bytes.patch
maintainers-add-myself-as-vmalloc-reviewer.patch
mm-remove-unused-vmf_insert_mixed_prot.patch
mm-remove-vmf_insert_pfn_xxx_prot-for-huge-page-table-entries.patch
drm-ttm-remove-comment-referencing-now-removed-vmf_insert_mixed_prot.patch
fs-proc-kcore-avoid-bounce-buffer-for-ktext-data.patch
fs-proc-kcore-convert-read_kcore-to-read_kcore_iter.patch
iov_iter-add-copy_page_to_iter_atomic.patch
mm-vmalloc-convert-vread-to-vread_iter.patch
mm-mmap-vma_merge-further-improve-prev-next-vma-naming.patch
mm-mmap-vma_merge-fold-curr-next-assignment-logic.patch
mm-mmap-vma_merge-explicitly-assign-res-vma-extend-invariants.patch
mm-mmap-vma_merge-init-cleanup-be-explicit-about-the-non-mergeable-case.patch
