From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl1-f200.google.com (mail-pl1-f200.google.com [209.85.214.200]) by kanga.kvack.org (Postfix) with ESMTP id 1F6EE6B0005 for ; Wed, 24 Oct 2018 09:54:57 -0400 (EDT) Received: by mail-pl1-f200.google.com with SMTP id be11-v6so2711909plb.2 for ; Wed, 24 Oct 2018 06:54:57 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id f185-v6si4607924pgc.339.2018.10.24.06.54.54 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 24 Oct 2018 06:54:55 -0700 (PDT) Date: Wed, 24 Oct 2018 15:54:52 +0200 From: Michal Hocko Subject: Re: [PATCH V3 1/5] mm/hugetlb: Distinguish between migratability and movability Message-ID: <20181024135452.GG18839@dhcp22.suse.cz> References: <1540299721-26484-1-git-send-email-anshuman.khandual@arm.com> <1540299721-26484-2-git-send-email-anshuman.khandual@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1540299721-26484-2-git-send-email-anshuman.khandual@arm.com> Sender: owner-linux-mm@kvack.org List-ID: To: Anshuman Khandual Cc: linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, suzuki.poulose@arm.com, punit.agrawal@arm.com, will.deacon@arm.com, Steven.Price@arm.com, steve.capper@arm.com, catalin.marinas@arm.com, akpm@linux-foundation.org, mike.kravetz@oracle.com, n-horiguchi@ah.jp.nec.com 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 > Suggested-by: Michal Hocko > Signed-off-by: Anshuman Khandual Acked-by: Michal Hocko 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