On Fri, 14 Jul 2023, Yin, Fengwei wrote: > On 7/14/2023 10:21 AM, Hugh Dickins wrote: > > On Wed, 12 Jul 2023, Yin Fengwei wrote: > >> On 7/12/23 14:23, Yu Zhao wrote: > >>> On Wed, Jul 12, 2023 at 12:02 AM Yin Fengwei <fengwei.yin@xxxxxxxxx> wrote: > >>>> --- a/ > >>>> +++ b/mm/internal.h > >>>> @@ -643,7 +643,8 @@ static inline void mlock_vma_folio(struct folio *folio, > >>>> * still be set while VM_SPECIAL bits are added: so ignore it then. > >>>> */ > >>>> if (unlikely((vma->vm_flags & (VM_LOCKED|VM_SPECIAL)) == VM_LOCKED) && > >>>> - (compound || !folio_test_large(folio))) > >>>> + (compound || !folio_test_large(folio) || > >>>> + folio_in_range(folio, vma, vma->vm_start, vma->vm_end))) > >>>> mlock_folio(folio); > >>>> } > >>> > >>> This can be simplified: > >>> 1. remove the compound parameter > >> Yes. There is not difference here for pmd mapping of THPs and pte mappings of THPs > >> if the only condition need check is whether the folio is within VMA range or not. > >> > >> But let me add Huge for confirmation. > > > > I'm not sure what it is that you need me to confirm: if the folio fits > > within the vma, then the folio fits within the vma, pmd-mapped or not. > Sorry. My bad. I should speak it out for what I want your confirmation: > Whether we can remove the compound and use whether folio is within > VMA instead. > > I suppose you answer is Yes. Yes (if it all works out going that way). > > > > > (And I agree with Yu that it's better to drop the folio_test_large() > > check too.) > My argument was folio_test_large() can filter the normal 4K page out so > it doesn't need to call folio_in_range() which looks to me a little bit > heavy for normal 4K page. And the deal was move folio_test_large() > to folio_in_range() like function so simplify the code in caller side. I realized that, but agree with Yu. It looked a little over-engineered to me, but I didn't spend long enough looking to understand why there's folio_within_vma() distinct from folio_in_range(), when everyone(?) calls folio_in_range() with the same arguments vma->vm_start, vma->vm_end. > > > > > This idea, of counting the folio as mlocked according to whether the > > whole folio fits within the vma, does seem a good idea to me: worth > > pursuing. But whether the implementation adds up and works out, I > > have not checked. It was always difficult to arrive at a satisfactory > > compromise in mlocking compound pages: I hope this way does work out. > This is the purpose of this patch. :). Thanks. > > > Regards > Yin, Fengwei > > > > > Hugh
