The patch titled
Subject: mm: remove duplicated open-coded VMA policy check
has been added to the -mm mm-unstable branch. Its filename is
mm-remove-duplicated-open-coded-vma-policy-check.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-remove-duplicated-open-coded-vma-policy-check.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 <lorenzo.stoakes@xxxxxxxxxx>
Subject: mm: remove duplicated open-coded VMA policy check
Date: Fri, 23 Aug 2024 21:06:59 +0100
Both can_vma_merge_before() and can_vma_merge_after() are invoked after
checking for compatible VMA NUMA policy, we can simply move this to
is_mergeable_vma() and abstract this altogether.
In mmap_region() we set vmg->policy to NULL, so the policy comparisons
checked in can_vma_merge_before() and can_vma_merge_after() are exactly
equivalent to !vma_policy(vmg.next) and !vma_policy(vmg.prev).
Equally, in do_brk_flags(), vmg->policy is NULL, so the
can_vma_merge_after() is checking !vma_policy(vma), as we set vmg.prev to
vma.
In vma_merge(), we compare prev and next policies with vmg->policy before
checking can_vma_merge_after() and can_vma_merge_before() respectively,
which this patch causes to be checked in precisely the same way.
This therefore maintains precisely the same logic as before, only now
abstracted into is_mergeable_vma().
Link: https://lkml.kernel.org/r/c0b2c70cf5c7a036c560d9ddba7b2904b84ab9ab.1724441678.git.lorenzo.stoakes@xxxxxxxxxx
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Bert Karwatzki <spasswolf@xxxxxx>
Cc: Jiri Olsa <olsajiri@xxxxxxxxx>
Cc: Kees Cook <kees@xxxxxxxxxx>
Cc: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
Cc: Paul Moore <paul@xxxxxxxxxxxxxx>
Cc: Sidhartha Kumar <sidhartha.kumar@xxxxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mmap.c | 8 +++-----
mm/vma.c | 9 ++++-----
2 files changed, 7 insertions(+), 10 deletions(-)
--- a/mm/mmap.c~mm-remove-duplicated-open-coded-vma-policy-check
+++ a/mm/mmap.c
@@ -1423,8 +1423,7 @@ unsigned long mmap_region(struct file *f
/* Attempt to expand an old mapping */
/* Check next */
- if (next && next->vm_start == end && !vma_policy(next) &&
- can_vma_merge_before(&vmg)) {
+ if (next && next->vm_start == end && can_vma_merge_before(&vmg)) {
merge_end = next->vm_end;
vma = next;
vmg.pgoff = next->vm_pgoff - pglen;
@@ -1438,8 +1437,7 @@ unsigned long mmap_region(struct file *f
}
/* Check prev */
- if (prev && prev->vm_end == addr && !vma_policy(prev) &&
- can_vma_merge_after(&vmg)) {
+ if (prev && prev->vm_end == addr && can_vma_merge_after(&vmg)) {
merge_start = prev->vm_start;
vma = prev;
vmg.pgoff = prev->vm_pgoff;
@@ -1778,7 +1776,7 @@ static int do_brk_flags(struct vma_itera
* Expand the existing vma if possible; Note that singular lists do not
* occur after forking, so the expand will only happen on new VMAs.
*/
- if (vma && vma->vm_end == addr && !vma_policy(vma)) {
+ if (vma && vma->vm_end == addr) {
VMG_STATE(vmg, mm, vmi, addr, addr + len, flags, PHYS_PFN(addr));
vmg.prev = vma;
--- a/mm/vma.c~mm-remove-duplicated-open-coded-vma-policy-check
+++ a/mm/vma.c
@@ -19,6 +19,8 @@ static inline bool is_mergeable_vma(stru
*/
bool may_remove_vma = merge_next;
+ if (!mpol_equal(vmg->policy, vma_policy(vma)))
+ return false;
/*
* VM_SOFTDIRTY should not prevent from VMA merging, if we
* match the flags but dirty bit -- the caller should mark
@@ -1058,17 +1060,14 @@ static struct vm_area_struct *vma_merge(
vma_pgoff = prev->vm_pgoff;
/* Can we merge the predecessor? */
- if (addr == prev->vm_end && mpol_equal(vma_policy(prev), vmg->policy)
- && can_vma_merge_after(vmg)) {
-
+ if (addr == prev->vm_end && can_vma_merge_after(vmg)) {
merge_prev = true;
vma_prev(vmg->vmi);
}
}
/* Can we merge the successor? */
- if (next && mpol_equal(vmg->policy, vma_policy(next)) &&
- can_vma_merge_before(vmg)) {
+ if (next && can_vma_merge_before(vmg)) {
merge_next = true;
}
_
Patches currently in -mm which might be from lorenzo.stoakes@xxxxxxxxxx are
userfaultfd-move-core-vma-manipulation-logic-to-mm-userfaultfdc.patch
userfaultfd-move-core-vma-manipulation-logic-to-mm-userfaultfdc-fix.patch
mm-move-vma_modify-and-helpers-to-internal-header.patch
mm-move-vma_shrink-vma_expand-to-internal-header.patch
mm-move-internal-core-vma-manipulation-functions-to-own-file.patch
maintainers-add-entry-for-new-vma-files.patch
tools-separate-out-shared-radix-tree-components.patch
tools-add-skeleton-code-for-userland-testing-of-vma-logic.patch
tools-improve-vma-test-makefile.patch
tools-add-vma-merge-tests.patch
mm-introduce-vma_merge_struct-and-abstract-vma_mergevma_modify.patch
mm-remove-duplicated-open-coded-vma-policy-check.patch
mm-abstract-vma_expand-to-use-vma_merge_struct.patch
mm-avoid-using-vma_merge-for-new-vmas.patch
mm-make-vma_prepare-and-friends-static-and-internal-to-vmac.patch
mm-introduce-commit_merge-abstracting-final-commit-of-merge.patch
mm-refactor-vma_merge-into-modify-only-vma_merge_existing_range.patch
mm-rework-vm_ops-close-handling-on-vma-merge.patch
