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().
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Reviewed-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
---
mm/mmap.c | 8 +++-----
mm/vma.c | 9 ++++-----
2 files changed, 7 insertions(+), 10 deletions(-)
diff --git a/mm/mmap.c b/mm/mmap.c
index ca9c6939638b..3af8459e4e88 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1423,8 +1423,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
/* 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 *file, unsigned long addr,
}
/* 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;
@@ -1779,7 +1777,7 @@ static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma,
* 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;
diff --git a/mm/vma.c b/mm/vma.c
index 6be645240f07..3284bb778c3d 100644
--- a/mm/vma.c
+++ b/mm/vma.c
@@ -19,6 +19,8 @@ static inline bool is_mergeable_vma(struct vma_merge_struct *vmg, bool merge_nex
*/
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
@@ -1053,17 +1055,14 @@ static struct vm_area_struct *vma_merge(struct vma_merge_struct *vmg)
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;
}
--
2.46.0
