From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 51488C4363C for ; Fri, 2 Oct 2020 17:26:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1A10D208A9 for ; Fri, 2 Oct 2020 17:26:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="Xj5N3CbU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388310AbgJBR0Q (ORCPT ); Fri, 2 Oct 2020 13:26:16 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:32406 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388219AbgJBR0I (ORCPT ); Fri, 2 Oct 2020 13:26:08 -0400 Received: from pps.filterd (m0109332.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 092HEW24017232 for ; Fri, 2 Oct 2020 10:26:06 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : content-type; s=facebook; bh=l1tkVR7FIxY7yu4rFMtlPopAY7rcxWQQ8dOmIsWQsOY=; b=Xj5N3CbUE2jYjk83Fzwic6zPD+AtZCnf0iUDddDtpOppRjlJY3MSZDfKh4wOvaLe4hAW pzNalBkkm0ggmookIGmYRPGDW8cZKBx4akspYpoOMbe46vfA4XcL+poEoGt0z0IekKkZ VnR+/FxtpHRJ2hBAGQ27Bgm7lHreXX35C6A= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com with ESMTP id 33x6gu8tck-7 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Fri, 02 Oct 2020 10:26:06 -0700 Received: from intmgw001.41.prn1.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Fri, 2 Oct 2020 10:26:04 -0700 Received: by devvm1755.vll0.facebook.com (Postfix, from userid 111017) id C7224F152A3; Fri, 2 Oct 2020 10:26:00 -0700 (PDT) From: Roman Gushchin To: Andrew Morton CC: Shakeel Butt , Johannes Weiner , Michal Hocko , , , , Roman Gushchin Subject: [PATCH v5 4/4] mm: convert page kmemcg type to a page memcg flag Date: Fri, 2 Oct 2020 10:25:59 -0700 Message-ID: <20201002172559.4000748-5-guro@fb.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20201002172559.4000748-1-guro@fb.com> References: <20201002172559.4000748-1-guro@fb.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-10-02_11:2020-10-02,2020-10-02 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 lowpriorityscore=0 mlxlogscore=884 spamscore=0 mlxscore=0 clxscore=1015 bulkscore=0 suspectscore=2 phishscore=0 priorityscore=1501 impostorscore=0 adultscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2010020129 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org PageKmemcg flag is currently defined as a page type (like buddy, offline, table and guard). Semantically it means that the page was accounted as a kernel memory by the page allocator and has to be uncharged on the release. As a side effect of defining the flag as a page type, the accounted page can't be mapped to userspace (look at page_has_type() and comments above). In particular, this blocks the accounting of vmalloc-backed memory used by some bpf maps, because these maps do map the memory to userspace. One option is to fix it by complicating the access to page->mapcount, which provides some free bits for page->page_type. But it's way better to move this flag into page->memcg_data flags. Indeed, the flag makes no sense without enabled memory cgroups and memory cgroup pointer set in particular. This commit replaces PageKmemcg() and __SetPageKmemcg() with PageMemcgKmem() and an open-coded OR operation setting the memcg pointer with the MEMCG_DATA_KMEM bit. __ClearPageKmemcg() can be simple deleted, as the whole memcg_data is zeroed at once. As a bonus, on !CONFIG_MEMCG build the PageMemcgKmem() check will be compiled out. Signed-off-by: Roman Gushchin Acked-by: Johannes Weiner --- cover.txt | 4 ++-- include/linux/memcontrol.h | 37 +++++++++++++++++++++++++++++++++---- include/linux/page-flags.h | 11 ++--------- mm/memcontrol.c | 16 +++++----------- mm/page_alloc.c | 4 ++-- 5 files changed, 44 insertions(+), 28 deletions(-) diff --git a/cover.txt b/cover.txt index 32460cd3316e..cf23753cad15 100644 --- a/cover.txt +++ b/cover.txt @@ -15,10 +15,10 @@ their memory can't be accounted because of this imple= mentation detail. =20 This patchset removes this limitation by moving the PageKmemcg flag into one of the free bits of the page->mem_cgroup pointer. Also it -formalizes all accesses to the page->mem_cgroup and page->obj_cgroups +formalizes accesses to the page->mem_cgroup and page->obj_cgroups using new helpers, adds several checks and removes a couple of obsolete functions. As the result the code became more robust with fewer -open-coded bits tricks. +open-coded bit tricks. =20 v5: - added ~MEMCG_DATA_FLAGS_MASK to page_memcg_rcu(), by Michal diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 99a4841d658b..7c9d43476166 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -346,8 +346,10 @@ extern struct mem_cgroup *root_mem_cgroup; enum page_memcg_data_flags { /* page->memcg_data is a pointer to an objcgs vector */ MEMCG_DATA_OBJCGS =3D (1UL << 0), + /* page has been accounted as a non-slab kernel page */ + MEMCG_DATA_KMEM =3D (1UL << 1), /* the next bit after the last actual flag */ - __NR_MEMCG_DATA_FLAGS =3D (1UL << 1), + __NR_MEMCG_DATA_FLAGS =3D (1UL << 2), }; =20 #define MEMCG_DATA_FLAGS_MASK (__NR_MEMCG_DATA_FLAGS - 1) @@ -369,8 +371,12 @@ enum page_memcg_data_flags { */ static inline struct mem_cgroup *page_memcg(struct page *page) { + unsigned long memcg_data =3D page->memcg_data; + VM_BUG_ON_PAGE(PageSlab(page), page); - return (struct mem_cgroup *)page->memcg_data; + VM_BUG_ON_PAGE(memcg_data & MEMCG_DATA_OBJCGS, page); + + return (struct mem_cgroup *)(memcg_data & ~MEMCG_DATA_FLAGS_MASK); } =20 /* @@ -387,7 +393,8 @@ static inline struct mem_cgroup *page_memcg_rcu(struc= t page *page) VM_BUG_ON_PAGE(PageSlab(page), page); WARN_ON_ONCE(!rcu_read_lock_held()); =20 - return (struct mem_cgroup *)READ_ONCE(page->memcg_data); + return (struct mem_cgroup *)(READ_ONCE(page->memcg_data) & + ~MEMCG_DATA_FLAGS_MASK); } =20 /* @@ -416,7 +423,21 @@ static inline struct mem_cgroup *page_memcg_check(st= ruct page *page) if (memcg_data & MEMCG_DATA_OBJCGS) return NULL; =20 - return (struct mem_cgroup *)memcg_data; + return (struct mem_cgroup *)(memcg_data & ~MEMCG_DATA_FLAGS_MASK); +} + +/* + * PageMemcgKmem - check if the page has MemcgKmem flag set + * @page: a pointer to the page struct + * + * Checks if the page has MemcgKmem flag set. The caller must ensure tha= t + * the page has an associated memory cgroup. It's not safe to call this = function + * against some types of pages, e.g. slab pages. + */ +static inline bool PageMemcgKmem(struct page *page) +{ + VM_BUG_ON_PAGE(page->memcg_data & MEMCG_DATA_OBJCGS, page); + return page->memcg_data & MEMCG_DATA_KMEM; } =20 #ifdef CONFIG_MEMCG_KMEM @@ -435,6 +456,7 @@ static inline struct obj_cgroup **page_objcgs(struct = page *page) unsigned long memcg_data =3D READ_ONCE(page->memcg_data); =20 VM_BUG_ON_PAGE(memcg_data && !(memcg_data & MEMCG_DATA_OBJCGS), page); + VM_BUG_ON_PAGE(memcg_data & MEMCG_DATA_KMEM, page); =20 return (struct obj_cgroup **)(memcg_data & ~MEMCG_DATA_FLAGS_MASK); } @@ -454,6 +476,8 @@ static inline struct obj_cgroup **page_objcgs_check(s= truct page *page) if (!memcg_data || !(memcg_data & MEMCG_DATA_OBJCGS)) return NULL; =20 + VM_BUG_ON_PAGE(memcg_data & MEMCG_DATA_KMEM, page); + return (struct obj_cgroup **)(memcg_data & ~MEMCG_DATA_FLAGS_MASK); } =20 @@ -1109,6 +1133,11 @@ static inline struct mem_cgroup *page_memcg_check(= struct page *page) return NULL; } =20 +static inline bool PageMemcgKmem(struct page *page) +{ + return false; +} + static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg) { return true; diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 4f6ba9379112..fc0e1bd48e73 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -715,9 +715,8 @@ PAGEFLAG_FALSE(DoubleMap) #define PAGE_MAPCOUNT_RESERVE -128 #define PG_buddy 0x00000080 #define PG_offline 0x00000100 -#define PG_kmemcg 0x00000200 -#define PG_table 0x00000400 -#define PG_guard 0x00000800 +#define PG_table 0x00000200 +#define PG_guard 0x00000400 =20 #define PageType(page, flag) \ ((page->page_type & (PAGE_TYPE_BASE | flag)) =3D=3D PAGE_TYPE_BASE) @@ -768,12 +767,6 @@ PAGE_TYPE_OPS(Buddy, buddy) */ PAGE_TYPE_OPS(Offline, offline) =20 -/* - * If kmemcg is enabled, the buddy allocator will set PageKmemcg() on - * pages allocated with __GFP_ACCOUNT. It gets cleared on page free. - */ -PAGE_TYPE_OPS(Kmemcg, kmemcg) - /* * Marks pages in use as page tables. */ diff --git a/mm/memcontrol.c b/mm/memcontrol.c index a8eb20283dcd..e3fc240101ff 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3090,8 +3090,8 @@ int __memcg_kmem_charge_page(struct page *page, gfp= _t gfp, int order) if (memcg && !mem_cgroup_is_root(memcg)) { ret =3D __memcg_kmem_charge(memcg, gfp, 1 << order); if (!ret) { - page->memcg_data =3D (unsigned long)memcg; - __SetPageKmemcg(page); + page->memcg_data =3D (unsigned long)memcg | + MEMCG_DATA_KMEM; return 0; } css_put(&memcg->css); @@ -3116,10 +3116,6 @@ void __memcg_kmem_uncharge_page(struct page *page,= int order) __memcg_kmem_uncharge(memcg, nr_pages); page->memcg_data =3D 0; css_put(&memcg->css); - - /* slab pages do not have PageKmemcg flag set */ - if (PageKmemcg(page)) - __ClearPageKmemcg(page); } =20 static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_= bytes) @@ -6863,12 +6859,10 @@ static void uncharge_page(struct page *page, stru= ct uncharge_gather *ug) nr_pages =3D compound_nr(page); ug->nr_pages +=3D nr_pages; =20 - if (!PageKmemcg(page)) { - ug->pgpgout++; - } else { + if (PageMemcgKmem(page)) ug->nr_kmem +=3D nr_pages; - __ClearPageKmemcg(page); - } + else + ug->pgpgout++; =20 ug->dummy_page =3D page; page->memcg_data =3D 0; diff --git a/mm/page_alloc.c b/mm/page_alloc.c index e9f0fe4a143e..5ebd50183d93 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1179,7 +1179,7 @@ static __always_inline bool free_pages_prepare(stru= ct page *page, * Do not let hwpoison pages hit pcplists/buddy * Untie memcg state and reset page's owner */ - if (memcg_kmem_enabled() && PageKmemcg(page)) + if (memcg_kmem_enabled() && PageMemcgKmem(page)) __memcg_kmem_uncharge_page(page, order); reset_page_owner(page, order); return false; @@ -1209,7 +1209,7 @@ static __always_inline bool free_pages_prepare(stru= ct page *page, } if (PageMappingFlags(page)) page->mapping =3D NULL; - if (memcg_kmem_enabled() && PageKmemcg(page)) + if (memcg_kmem_enabled() && PageMemcgKmem(page)) __memcg_kmem_uncharge_page(page, order); if (check_free) bad +=3D check_free_page(page); --=20 2.26.2