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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.
- clear_bit(MMF_VM_MERGE_ANY, &mm->flags);
- for_each_vma(vmi, vma) {
/* Copy vm_flags to avoid partial modifications in ksm_madvise */vm_flags = vma->vm_flags;ret = ksm_madvise(vma, vma->vm_start, vma->vm_end,MADV_UNMERGEABLE, &vm_flags);if (ret)return ret;vm_flags_reset(vma, vm_flags);- }
- mm->def_flags &= ~VM_MERGEABLE;
Hi Stefan,
This clears the def_flags struct member, however, in ksm_disable() we clear the __flags struct member. Is this a problem?
The patch description contains a comment regarding def_flags: "The existing "mm->def_flags &= ~VM_MERGEABLE;" was essentially a NOP and can be dropped, because def_flags should never include VM_MERGEABLE."
We keep clearing the MADV_UNMERGEABLE flag from MADV_UNMERGEABLE. In the old code, ksm_madvise() would have cleared it from local vm_flags and vm_flags_reset() would have modified vma->vm_flags. Now we clear it directly via vm_flags_clear(vma, VM_MERGEABLE);
Long story short, the mm->def_flags code as wrong and most probably copied from thp_split_mm() where we do: mm->def_flags |= VM_NOHUGEPAGE; Which makes more sense.
Thanks!