[PATCH RFC 3/5] mm/ksm: introduce ksm_madvise_unmerge() helper

Oleksandr Natalenko
2019-05-16T09:42:48Z

Move MADV_UNMERGEABLE part of ksm_madvise() into a dedicated helper
since it will be further used for unmerging VMAs forcibly.

This does not bring any functional changes.

Signed-off-by: Oleksandr Natalenko <oleksandr@redhat.com>
---
include/linux/ksm.h | 2 ++
mm/ksm.c | 32 ++++++++++++++++++++++----------
2 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/include/linux/ksm.h b/include/linux/ksm.h
index e824b3141677..a91a7cfc87a1 100644
--- a/include/linux/ksm.h
+++ b/include/linux/ksm.h
@@ -21,6 +21,8 @@ struct mem_cgroup;
#ifdef CONFIG_KSM
int ksm_madvise_merge(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long *vm_flags);
+int ksm_madvise_unmerge(struct vm_area_struct *vma, unsigned long start,
+ unsigned long end, unsigned long *vm_flags);
int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
unsigned long end, int advice, unsigned long *vm_flags);
int __ksm_enter(struct mm_struct *mm);
diff --git a/mm/ksm.c b/mm/ksm.c
index 1fdcf2fbd58d..e0357e25e09f 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -2478,6 +2478,25 @@ int ksm_madvise_merge(struct mm_struct *mm, struct vm_area_struct *vma,
return 0;
}

+int ksm_madvise_unmerge(struct vm_area_struct *vma, unsigned long start,
+ unsigned long end, unsigned long *vm_flags)
+{
+ int err;
+
+ if (!(*vm_flags & VM_MERGEABLE))
+ return 0; /* just ignore the advice */
+
+ if (vma->anon_vma) {
+ err = unmerge_ksm_pages(vma, start, end);
+ if (err)
+ return err;
+ }
+
+ *vm_flags &= ~VM_MERGEABLE;
+
+ return 0;
+}
+
int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
unsigned long end, int advice, unsigned long *vm_flags)
{
@@ -2492,16 +2511,9 @@ int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
break;

case MADV_UNMERGEABLE:
- if (!(*vm_flags & VM_MERGEABLE))
- return 0; /* just ignore the advice */
-
- if (vma->anon_vma) {
- err = unmerge_ksm_pages(vma, start, end);
- if (err)
- return err;
- }
-
- *vm_flags &= ~VM_MERGEABLE;
+ err = ksm_madvise_unmerge(vma, start, end, vm_flags);
+ if (err)
+ return err;
break;
}

--
2.21.0