On Tue 23-10-18 18:31:57, Anshuman Khandual wrote: > During huge page allocation it's migratability is checked to determine if > it should be placed under movable zones with GFP_HIGHUSER_MOVABLE. But the > movability aspect of the huge page could depend on other factors than just > migratability. Movability in itself is a distinct property which should not > be tied with migratability alone. > > This differentiates these two and implements an enhanced movability check > which also considers huge page size to determine if it is feasible to be > placed under a movable zone. At present it just checks for gigantic pages > but going forward it can incorporate other enhanced checks. > > Reviewed-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> > Suggested-by: Michal Hocko <mhocko@xxxxxxxxxx> > Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Thanks! > --- > include/linux/hugetlb.h | 30 ++++++++++++++++++++++++++++++ > mm/hugetlb.c | 2 +- > mm/migrate.c | 2 +- > 3 files changed, 32 insertions(+), 2 deletions(-) > > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > index 087fd5f4..1b858d7 100644 > --- a/include/linux/hugetlb.h > +++ b/include/linux/hugetlb.h > @@ -506,6 +506,31 @@ static inline bool hugepage_migration_supported(struct hstate *h) > #endif > } > > +/* > + * Movability check is different as compared to migration check. > + * It determines whether or not a huge page should be placed on > + * movable zone or not. Movability of any huge page should be > + * required only if huge page size is supported for migration. > + * There wont be any reason for the huge page to be movable if > + * it is not migratable to start with. Also the size of the huge > + * page should be large enough to be placed under a movable zone > + * and still feasible enough to be migratable. Just the presence > + * in movable zone does not make the migration feasible. > + * > + * So even though large huge page sizes like the gigantic ones > + * are migratable they should not be movable because its not > + * feasible to migrate them from movable zone. > + */ > +static inline bool hugepage_movable_supported(struct hstate *h) > +{ > + if (!hugepage_migration_supported(h)) > + return false; > + > + if (hstate_is_gigantic(h)) > + return false; > + return true; > +} > + > static inline spinlock_t *huge_pte_lockptr(struct hstate *h, > struct mm_struct *mm, pte_t *pte) > { > @@ -602,6 +627,11 @@ static inline bool hugepage_migration_supported(struct hstate *h) > return false; > } > > +static inline bool hugepage_movable_supported(struct hstate *h) > +{ > + return false; > +} > + > static inline spinlock_t *huge_pte_lockptr(struct hstate *h, > struct mm_struct *mm, pte_t *pte) > { > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 5c390f5..f810cf0 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -919,7 +919,7 @@ static struct page *dequeue_huge_page_nodemask(struct hstate *h, gfp_t gfp_mask, > /* Movability of hugepages depends on migration support. */ > static inline gfp_t htlb_alloc_mask(struct hstate *h) > { > - if (hugepage_migration_supported(h)) > + if (hugepage_movable_supported(h)) > return GFP_HIGHUSER_MOVABLE; > else > return GFP_HIGHUSER; > diff --git a/mm/migrate.c b/mm/migrate.c > index 84381b5..bfda9e4 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -1272,7 +1272,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page, > struct anon_vma *anon_vma = NULL; > > /* > - * Movability of hugepages depends on architectures and hugepage size. > + * Migratability of hugepages depends on architectures and their size. > * This check is necessary because some callers of hugepage migration > * like soft offline and memory hotremove don't walk through page > * tables or check whether the hugepage is pmd-based or not before > -- > 2.7.4 -- Michal Hocko SUSE Labs