nit:
can we do:
if (arg2)
error = ksm_enable_merge_any(me->mm);
else
error = ksm_disable_merge_any(me->mm);
mmap_write_unlock(me->mm);
break;
diff --git a/mm/ksm.c b/mm/ksm.c
index a959e8925413..813f7fbc1832 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -2520,6 +2520,22 @@ static void __ksm_add_vma(struct vm_area_struct *vma)
vm_flags_set(vma, VM_MERGEABLE);
}
+static int __ksm_del_vma(struct vm_area_struct *vma)
+{
+ int err;
+
+ if (!(vma->vm_flags & VM_MERGEABLE))
+ return 0;
+
+ if (vma->anon_vma) {
+ err = unmerge_ksm_pages(vma, vma->vm_start, vma->vm_end);
+ if (err)
+ return err;
+ }
+
+ vm_flags_clear(vma, VM_MERGEABLE);
+ return 0;
+}
/**
* ksm_add_vma - Mark vma as mergeable if compatible
*
@@ -2542,6 +2558,20 @@ static void ksm_add_vmas(struct mm_struct *mm)
__ksm_add_vma(vma);
}
+static int ksm_del_vmas(struct mm_struct *mm)
+{
+ struct vm_area_struct *vma;
+ int err;
+
+ VMA_ITERATOR(vmi, mm, 0);
+ for_each_vma(vmi, vma) {
+ err = __ksm_del_vma(vma);
+ if (err)
+ return err;
+ }
+ return 0;
+}
+
/**
* ksm_enable_merge_any - Add mm to mm ksm list and enable merging on all
* compatible VMA's
@@ -2569,6 +2599,23 @@ int ksm_enable_merge_any(struct mm_struct *mm)
return 0;
}
+int ksm_disable_merge_any(struct mm_struct *mm)
I understand we want to keep the name "symmetric" with
ksm_enable_merge_any, but it also unmerges the ksm pages. Do we want to
reflect that in the function name?
Can we add a comment for the function?
+{
+ int err;
+
+ if (!test_bit(MMF_VM_MERGE_ANY, &mm->flags))
+ return 0;
+
+ err = ksm_del_vmas(mm);
+ if (err) {
+ ksm_add_vmas(mm);
+ return err;
+ }
+
+ clear_bit(MMF_VM_MERGE_ANY, &mm->flags);
We only clear the MMF_VM_MERGE_ANY flag if there are no errors. Is this
what we want? This means that if the process creates new memory regions
they would still be marked as mergeable.