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Fri, 1 Oct 2021 17:52:41 +0000 From: Mike Kravetz To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: David Hildenbrand , Michal Hocko , Oscar Salvador , Zi Yan , Muchun Song , Naoya Horiguchi , David Rientjes , "Aneesh Kumar K . V" , Andrew Morton , Mike Kravetz Subject: [PATCH v3 5/5] hugetlb: add hugetlb demote page support Date: Fri, 1 Oct 2021 10:52:10 -0700 Message-Id: <20211001175210.45968-6-mike.kravetz@oracle.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20211001175210.45968-1-mike.kravetz@oracle.com> References: <20211001175210.45968-1-mike.kravetz@oracle.com> Content-Type: text/plain X-ClientProxiedBy: MWHPR22CA0060.namprd22.prod.outlook.com (2603:10b6:300:12a::22) To CH2PR10MB4200.namprd10.prod.outlook.com (2603:10b6:610:a5::9) MIME-Version: 1.0 Received: from monkey.oracle.com (50.38.35.18) by MWHPR22CA0060.namprd22.prod.outlook.com (2603:10b6:300:12a::22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4566.14 via Frontend Transport; Fri, 1 Oct 2021 17:52:40 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 7a75fcd4-7137-4040-eddc-08d9850443c7 X-MS-TrafficTypeDiagnostic: CH0PR10MB5228: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:6108; 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dkim=pass header.d=oracle.com header.s=corp-2021-07-09 header.b="L/Uf5yfD"; dkim=pass header.d=oracle.onmicrosoft.com header.s=selector2-oracle-onmicrosoft-com header.b=Tz+p5JV3; spf=none (imf27.hostedemail.com: domain of mike.kravetz@oracle.com has no SPF policy when checking 205.220.165.32) smtp.mailfrom=mike.kravetz@oracle.com; dmarc=pass (policy=none) header.from=oracle.com X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: C6EB1700196B X-Stat-Signature: t4z187aasqqtbpckua7nxgfizeu7tt1r X-HE-Tag: 1633110769-685834 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Demote page functionality will split a huge page into a number of huge pages of a smaller size. For example, on x86 a 1GB huge page can be demoted into 512 2M huge pages. Demotion is done 'in place' by simply splitting the huge page. Added '*_for_demote' wrappers for remove_hugetlb_page, destroy_compound_gigantic_page and prep_compound_gigantic_page for use by demote code. Signed-off-by: Mike Kravetz --- mm/hugetlb.c | 82 +++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 74 insertions(+), 8 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index ccbe323c992b..aec2e737d0cd 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1270,7 +1270,7 @@ static int hstate_next_node_to_free(struct hstate *= h, nodemask_t *nodes_allowed) ((node =3D hstate_next_node_to_free(hs, mask)) || 1); \ nr_nodes--) =20 -#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE +/* used to demote non-gigantic_huge pages as well */ static void __destroy_compound_gigantic_page(struct page *page, unsigned int order, bool demote) { @@ -1293,6 +1293,13 @@ static void __destroy_compound_gigantic_page(struc= t page *page, __ClearPageHead(page); } =20 +static void destroy_compound_gigantic_page_for_demote(struct page *page, + unsigned int order) +{ + __destroy_compound_gigantic_page(page, order, true); +} + +#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE static void destroy_compound_gigantic_page(struct page *page, unsigned int order) { @@ -1438,6 +1445,12 @@ static void remove_hugetlb_page(struct hstate *h, = struct page *page, __remove_hugetlb_page(h, page, adjust_surplus, false); } =20 +static void remove_hugetlb_page_for_demote(struct hstate *h, struct page= *page, + bool adjust_surplus) +{ + __remove_hugetlb_page(h, page, adjust_surplus, true); +} + static void add_hugetlb_page(struct hstate *h, struct page *page, bool adjust_surplus) { @@ -1779,6 +1792,12 @@ static bool prep_compound_gigantic_page(struct pag= e *page, unsigned int order) return __prep_compound_gigantic_page(page, order, false); } =20 +static bool prep_compound_gigantic_page_for_demote(struct page *page, + unsigned int order) +{ + return __prep_compound_gigantic_page(page, order, true); +} + /* * PageHuge() only returns true for hugetlbfs pages, but not for normal = or * transparent huge pages. See the PageTransHuge() documentation for mo= re @@ -3302,9 +3321,54 @@ static int set_max_huge_pages(struct hstate *h, un= signed long count, int nid, return 0; } =20 +static int demote_free_huge_page(struct hstate *h, struct page *page) +{ + int i, nid =3D page_to_nid(page); + struct hstate *target_hstate; + int rc =3D 0; + + target_hstate =3D size_to_hstate(PAGE_SIZE << h->demote_order); + + remove_hugetlb_page_for_demote(h, page, false); + spin_unlock_irq(&hugetlb_lock); + + rc =3D alloc_huge_page_vmemmap(h, page); + if (rc) { + /* Allocation of vmemmmap failed, we can not demote page */ + spin_lock_irq(&hugetlb_lock); + set_page_refcounted(page); + add_hugetlb_page(h, page, false); + return rc; + } + + /* + * Use destroy_compound_gigantic_page_for_demote for all huge page + * sizes as it will not ref count pages. + */ + destroy_compound_gigantic_page_for_demote(page, huge_page_order(h)); + + for (i =3D 0; i < pages_per_huge_page(h); + i +=3D pages_per_huge_page(target_hstate)) { + if (hstate_is_gigantic(target_hstate)) + prep_compound_gigantic_page_for_demote(page + i, + target_hstate->order); + else + prep_compound_page(page + i, target_hstate->order); + set_page_private(page + i, 0); + set_page_refcounted(page + i); + prep_new_huge_page(target_hstate, page + i, nid); + put_page(page + i); + } + + spin_lock_irq(&hugetlb_lock); + return rc; +} + static int demote_pool_huge_page(struct hstate *h, nodemask_t *nodes_all= owed) __must_hold(&hugetlb_lock) { + int nr_nodes, node; + struct page *page; int rc =3D 0; =20 lockdep_assert_held(&hugetlb_lock); @@ -3313,9 +3377,15 @@ static int demote_pool_huge_page(struct hstate *h,= nodemask_t *nodes_allowed) if (!h->demote_order) return rc; =20 - /* - * TODO - demote fucntionality will be added in subsequent patch - */ + for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) { + if (!list_empty(&h->hugepage_freelists[node])) { + page =3D list_entry(h->hugepage_freelists[node].next, + struct page, lru); + rc =3D !demote_free_huge_page(h, page); + break; + } + } + return rc; } =20 @@ -3550,10 +3620,6 @@ static ssize_t demote_store(struct kobject *kobj, /* * Check for available pages to demote each time thorough the * loop as demote_pool_huge_page will drop hugetlb_lock. - * - * NOTE: demote_pool_huge_page does not yet drop hugetlb_lock - * but will when full demote functionality is added in a later - * patch. */ if (nid !=3D NUMA_NO_NODE) nr_available =3D h->free_huge_pages_node[nid]; --=20 2.31.1