On 19.04.23 13:39, Janosch Frank wrote:
On 4/18/23 17:28, David Hildenbrand wrote:
Let's factor out actual disabling of KSM. The existing
"mm->def_flags &= ~VM_MERGEABLE;" was essentially a NOP and can be dropped,
because def_flags should never include VM_MERGEABLE. Note that we don't
currently prevent re-enabling KSM.
This should now be faster in case KSM was never enabled, because we only
conditionally iterate all VMAs. Further, it certainly looks cleaner.
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
arch/s390/mm/gmap.c | 20 +-------------------
include/linux/ksm.h | 6 ++++++
mm/ksm.c | 11 +++++++++++
3 files changed, 18 insertions(+), 19 deletions(-)
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index 0949811761e6..dfe905c7bd8e 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -2585,30 +2585,12 @@ EXPORT_SYMBOL_GPL(s390_enable_sie);
int gmap_mark_unmergeable(void)
{
- struct mm_struct *mm = current->mm;
- struct vm_area_struct *vma;
- unsigned long vm_flags;
- int ret;
- VMA_ITERATOR(vmi, mm, 0);
-
/*
* Make sure to disable KSM (if enabled for the whole process or
* individual VMAs). Note that nothing currently hinders user space
* from re-enabling it.
*/
Is that still true?
Yes. We'd need another per-MM bit to stop it from getting re-enabled.
My KSM knowledge is nearly zero but from what I can see the patch looks
ok to me:
Acked-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
Thanks!
--
Thanks,
David / dhildenb
