The patch titled
Subject: mm/mmap/vma_merge: set next to NULL if not applicable
has been added to the -mm mm-unstable branch. Its filename is
mm-mmap-vma_merge-set-next-to-null-if-not-applicable.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-set-next-to-null-if-not-applicable.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Subject: mm/mmap/vma_merge: set next to NULL if not applicable
Date: Tue, 21 Mar 2023 20:45:56 +0000
We are only interested in next if end == next->vm_start (in which case we
check to see if we can set merge_next), so perform this check alongside
checking whether curr should be set.
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/3506997a8146a287ec13ee7a53cf916707537bf8.1679431180.git.lstoakes@xxxxxxxxx
Signed-off-by: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Liam Howlett <liam.howlett@xxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Vernon Yang <vernon2gm@xxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mmap.c | 25 ++++++++++++-------------
1 file changed, 12 insertions(+), 13 deletions(-)
--- a/mm/mmap.c~mm-mmap-vma_merge-set-next-to-null-if-not-applicable
+++ a/mm/mmap.c
@@ -930,15 +930,15 @@ 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 && end == curr->vm_end)
+ /* Is there is a VMA immediately adjacent (cases 6 - 8)? */
+ next = vma_lookup(mm, curr->vm_end);
+ else if (!curr)
+ /* Is there a VMA next to a hole (case 1 - 3) or prev (4)? */
+ next = vma_lookup(mm, end);
/* verify some invariant that must be enforced by the caller */
VM_WARN_ON(prev && addr <= prev->vm_start);
@@ -959,11 +959,10 @@ 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
fs-proc-kcore-avoid-bounce-buffer-for-ktext-data.patch
mm-vmalloc-use-rwsem-mutex-for-vmap_area_lock-and-vmap_block-lock.patch
fs-proc-kcore-convert-read_kcore-to-read_kcore_iter.patch
mm-vmalloc-convert-vread-to-vread_iter.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
mm-mmap-vma_merge-further-improve-prev-next-vma-naming.patch
mm-mmap-vma_merge-set-next-to-null-if-not-applicable.patch
mm-mmap-vma_merge-extend-invariants-avoid-invalid-res-vma.patch
mm-mmap-vma_merge-init-cleanup-be-explicit-about-the-non-mergeable-case.patch
