[RFC,v2,02/19] mm: add flag to __ksm_enter

Commit Message

Stefan Roesch Feb. 10, 2023, 9:50 p.m. UTC

This change adds the flag parameter to __ksm_enter. This allows to
distinguish if ksm was called by prctl or madvise.

Signed-off-by: Stefan Roesch <[e-mail]>
---
 include/linux/ksm.h | 6 ++++--
 mm/ksm.c            | 9 +++++----
 2 files changed, 9 insertions(+), 6 deletions(-)

Patch

diff --git a/include/linux/ksm.h b/include/linux/ksm.h
index 7e232ba59b86..50e6b56092f3 100644
--- a/include/linux/ksm.h
+++ b/include/linux/ksm.h
@@ -18,13 +18,15 @@ 
 #ifdef CONFIG_KSM
 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);
 void __ksm_exit(struct mm_struct *mm);
+int __ksm_enter(struct mm_struct *mm, int flag);
 
 static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
 {
+	if (test_bit(MMF_VM_MERGE_ANY, &oldmm->flags))
+		return __ksm_enter(mm, MMF_VM_MERGE_ANY);
 	if (test_bit(MMF_VM_MERGEABLE, &oldmm->flags))
-		return __ksm_enter(mm);
+		return __ksm_enter(mm, MMF_VM_MERGEABLE);
 	return 0;
 }
 
diff --git a/mm/ksm.c b/mm/ksm.c
index 56808e3bfd19..afc0980592af 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -2595,8 +2595,9 @@  int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
 			return 0;
 #endif
 
-		if (!test_bit(MMF_VM_MERGEABLE, &mm->flags)) {
-			err = __ksm_enter(mm);
+		if (!test_bit(MMF_VM_MERGEABLE, &mm->flags) &&
+		    !test_bit(MMF_VM_MERGE_ANY, &mm->flags)) {
+			err = __ksm_enter(mm, MMF_VM_MERGEABLE);
 			if (err)
 				return err;
 		}
@@ -2622,7 +2623,7 @@  int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
 }
 EXPORT_SYMBOL_GPL(ksm_madvise);
 
-int __ksm_enter(struct mm_struct *mm)
+int __ksm_enter(struct mm_struct *mm, int flag)
 {
 	struct ksm_mm_slot *mm_slot;
 	struct mm_slot *slot;
@@ -2655,7 +2656,7 @@  int __ksm_enter(struct mm_struct *mm)
 		list_add_tail(&slot->mm_node, &ksm_scan.mm_slot->slot.mm_node);
 	spin_unlock(&ksm_mmlist_lock);
 
-	set_bit(MMF_VM_MERGEABLE, &mm->flags);
+	set_bit(flag, &mm->flags);
 	mmgrab(mm);
 
 	if (needs_wakeup)