On 2/18/21 8:23 AM, Sean Christopherson wrote: > On Thu, Feb 18, 2021, Paolo Bonzini wrote: >> On 13/02/21 01:50, Sean Christopherson wrote: >>> >>> pfn = spte_to_pfn(iter.old_spte); >>> if (kvm_is_reserved_pfn(pfn) || >>> - (!PageTransCompoundMap(pfn_to_page(pfn)) && >>> - !kvm_is_zone_device_pfn(pfn))) >>> + iter.level >= kvm_mmu_max_mapping_level(kvm, slot, iter.gfn, >>> + pfn, PG_LEVEL_NUM)) >>> continue; >> >> >> This changes the test to PageCompound. Is it worth moving the change to >> patch 1? > > Yes? I originally did that in a separate patch, then changed my mind. > > If PageTransCompoundMap() also detects HugeTLB pages, then it is the "better" > option as it checks that the page is actually mapped huge. I dropped the > change > because PageTransCompound() is just a wrapper around PageCompound(), and so I > assumed PageTransCompoundMap() would detect HugeTLB pages, too. I'm not so > sure > about that after rereading the code, yet again.
I have not followed this thread, but HugeTLB hit my mail filter and I can help with this question. No, PageTransCompoundMap() will not detect HugeTLB. hugetlb pages do not use the compound_mapcount_ptr field. So, that final check/return in PageTransCompoundMap() will always be false. -- Mike Kravetz
