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. > > (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. > > 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
