On Sat, 27 Aug 2022 17:59:32 -0700 John Hubbard <jhubbard@xxxxxxxxxx> wrote: > > /* The zero page is always allowed to be pinned. */ Wow, that's really verbose :) --- a/include/linux/mm.h~mm-re-allow-pinning-of-zero-pfns-again-fix +++ a/include/linux/mm.h @@ -1544,11 +1544,7 @@ static inline bool is_longterm_pinnable_ if (mt == MIGRATE_CMA || mt == MIGRATE_ISOLATE) return false; #endif - /* - * The zero page might reside in a movable zone, however it may not - * be migrated and can therefore be pinned. The vfio subsystem pins - * user mappings including the zero page for IOMMU translation. - */ + /* The zero page may always be pinned */ if (is_zero_pfn(page_to_pfn(page))) return true; _
