On Wed, Jul 16, 2025 at 9:28 AM David Hildenbrand <david@redhat.com> wrote:
>
> On 14.07.25 02:32, Nico Pache wrote:
> > From: Baolin Wang <baolin.wang@linux.alibaba.com>
>
> Should the subject better be
>
> "mm/khugepaged: enable collapsing mTHPs even when PMD THPs are disabled"
Thank does read better.
>
> (in general, I assume all subjects should be prefixed by "mm/khugepaged:")
ehhh, seems like there's a mix of "mm/khugepaged", "khugepaged", and
"mm: khugepaged:" being used in other commits. I prefer using
khugepaged as it leaves me more space for the commit title
>
> >
> > We have now allowed mTHP collapse, but thp_vma_allowable_order() still only
> > checks if the PMD-sized mTHP is allowed to collapse. This prevents scanning
> > and collapsing of 64K mTHP when only 64K mTHP is enabled. Thus, we should
> > modify the checks to allow all large orders of anonymous mTHP.
> >
> > Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> > Signed-off-by: Nico Pache <npache@redhat.com>
> > ---
> > mm/khugepaged.c | 13 +++++++++----
> > 1 file changed, 9 insertions(+), 4 deletions(-)
> >
> > diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> > index 7a9c4edf0e23..3772dc0d78ea 100644
> > --- a/mm/khugepaged.c
> > +++ b/mm/khugepaged.c
> > @@ -491,8 +491,11 @@ void khugepaged_enter_vma(struct vm_area_struct *vma,
> > {
> > if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) &&
> > hugepage_pmd_enabled()) {
> > - if (thp_vma_allowable_order(vma, vm_flags, TVA_ENFORCE_SYSFS,
> > - PMD_ORDER))
> > + unsigned long orders = vma_is_anonymous(vma) ?
> > + THP_ORDERS_ALL_ANON : BIT(PMD_ORDER);
> > +
> > + if (thp_vma_allowable_orders(vma, vm_flags, TVA_ENFORCE_SYSFS,
> > + orders))
> > __khugepaged_enter(vma->vm_mm);
> > }
> > }
> > @@ -2624,6 +2627,8 @@ static unsigned int collapse_scan_mm_slot(unsigned int pages, int *result,
> >
> > vma_iter_init(&vmi, mm, khugepaged_scan.address);
> > for_each_vma(vmi, vma) {
> > + unsigned long orders = vma_is_anonymous(vma) ?
> > + THP_ORDERS_ALL_ANON : BIT(PMD_ORDER);
> > unsigned long hstart, hend;
> >
> > cond_resched();
> > @@ -2631,8 +2636,8 @@ static unsigned int collapse_scan_mm_slot(unsigned int pages, int *result,
> > progress++;
> > break;
> > }
> > - if (!thp_vma_allowable_order(vma, vma->vm_flags,
> > - TVA_ENFORCE_SYSFS, PMD_ORDER)) {
> > + if (!thp_vma_allowable_orders(vma, vma->vm_flags,
> > + TVA_ENFORCE_SYSFS, orders)) {
> > skip:
> > progress++;
> > continue;
>
> Acked-by: David Hildenbrand <david@redhat.com>
Thank you for your review :)
>
> --
> Cheers,
>
> David / dhildenb
>