From: Anshuman Khandual <anshuman.khandual@xxxxxxx> Subject: mm/hugetlb: enable arch specific huge page size support for migration Architectures like arm64 have HugeTLB page sizes which are different than generic sizes at PMD, PUD, PGD level and implemented via contiguous bits. At present these special size HugeTLB pages cannot be identified through macros like (PMD|PUD|PGDIR)_SHIFT and hence chosen not be migrated. Enabling migration support for these special HugeTLB page sizes along with the generic ones (PMD|PUD|PGD) would require identifying all of them on a given platform. A platform specific hook can precisely enumerate all huge page sizes supported for migration. Instead of comparing against standard huge page orders let hugetlb_migration_support() function call a platform hook arch_hugetlb_migration_support(). Default definition for the platform hook maintains existing semantics which checks standard huge page order. But an architecture can choose to override the default and provide support for a comprehensive set of huge page sizes. Link: http://lkml.kernel.org/r/1545121450-1663-4-git-send-email-anshuman.khandual@xxxxxxx Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx> Reviewed-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> Reviewed-by: Steve Capper <steve.capper@xxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/hugetlb.h | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) --- a/include/linux/hugetlb.h~mm-hugetlb-enable-arch-specific-huge-page-size-support-for-migration +++ a/include/linux/hugetlb.h @@ -493,18 +493,29 @@ static inline pgoff_t basepage_index(str extern int dissolve_free_huge_page(struct page *page); extern int dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn); -static inline bool hugepage_migration_supported(struct hstate *h) -{ + #ifdef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION +#ifndef arch_hugetlb_migration_supported +static inline bool arch_hugetlb_migration_supported(struct hstate *h) +{ if ((huge_page_shift(h) == PMD_SHIFT) || (huge_page_shift(h) == PUD_SHIFT) || (huge_page_shift(h) == PGDIR_SHIFT)) return true; else return false; +} +#endif #else +static inline bool arch_hugetlb_migration_supported(struct hstate *h) +{ return false; +} #endif + +static inline bool hugepage_migration_supported(struct hstate *h) +{ + return arch_hugetlb_migration_supported(h); } /* _
