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=-12.9 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 71100C55178 for ; Tue, 27 Oct 2020 00:17:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2E93F20723 for ; Tue, 27 Oct 2020 00:17:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="eaC16wdk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2440778AbgJ0AR1 (ORCPT ); Mon, 26 Oct 2020 20:17:27 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:50346 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2411559AbgJ0ARN (ORCPT ); Mon, 26 Oct 2020 20:17:13 -0400 Received: from pps.filterd (m0109334.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 09R0ECNM021692 for ; Mon, 26 Oct 2020 17:17:13 -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=3rIRSirqbzeluC/DfnXT13ZlbHjK+JwhEzfsOd/ByQU=; b=eaC16wdkYCbuqawmvGz3hPrTmO2OKQBi7llbd8v5QVXzd/cGAqSjtaoBx/lsYgXEuMJz l26INIS8/xQYAVGNolJlDDo/LE2J7zcXjSk3t54sOWSLN+B2mgeH/Y4O7iJNBd4jZhb+ q+HuC5vd2bwzSPT/MVuKcXDUyGTEROe+MNc= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com with ESMTP id 34d43k8agr-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Mon, 26 Oct 2020 17:17:13 -0700 Received: from intmgw002.06.prn3.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:82::e) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Mon, 26 Oct 2020 17:17:11 -0700 Received: by devvm1755.vll0.facebook.com (Postfix, from userid 111017) id 80EFA1C56459; Mon, 26 Oct 2020 17:17:04 -0700 (PDT) From: Roman Gushchin To: Andrew Morton CC: Shakeel Butt , Johannes Weiner , Michal Hocko , , , , Roman Gushchin , Michal Hocko Subject: [PATCH v6 3/4] mm: introduce page memcg flags Date: Mon, 26 Oct 2020 17:16:56 -0700 Message-ID: <20201027001657.3398190-4-guro@fb.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20201027001657.3398190-1-guro@fb.com> References: <20201027001657.3398190-1-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=2.50.10434:6.0.235,18.0.737 definitions=2020-10-26_17:2020-10-26,2020-10-26 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 spamscore=0 mlxscore=0 malwarescore=0 lowpriorityscore=0 clxscore=1015 suspectscore=0 mlxlogscore=328 phishscore=0 priorityscore=1501 impostorscore=0 bulkscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2010270000 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The lowest bit in page->memcg_data is used to distinguish between struct memory_cgroup pointer and a pointer to a objcgs array. All checks and modifications of this bit are open-coded. Let's formalize it using page memcg flags, defined in enum page_memcg_data_flags. Additional flags might be added later. Signed-off-by: Roman Gushchin Reviewed-by: Shakeel Butt Acked-by: Johannes Weiner Acked-by: Michal Hocko --- include/linux/memcontrol.h | 32 ++++++++++++++++++++------------ 1 file changed, 20 insertions(+), 12 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index c7ac0a5b8989..99a4841d658b 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -343,6 +343,15 @@ struct mem_cgroup { =20 extern struct mem_cgroup *root_mem_cgroup; =20 +enum page_memcg_data_flags { + /* page->memcg_data is a pointer to an objcgs vector */ + MEMCG_DATA_OBJCGS =3D (1UL << 0), + /* the next bit after the last actual flag */ + __NR_MEMCG_DATA_FLAGS =3D (1UL << 1), +}; + +#define MEMCG_DATA_FLAGS_MASK (__NR_MEMCG_DATA_FLAGS - 1) + /* * page_memcg - get the memory cgroup associated with a page * @page: a pointer to the page struct @@ -404,13 +413,7 @@ static inline struct mem_cgroup *page_memcg_check(st= ruct page *page) */ unsigned long memcg_data =3D READ_ONCE(page->memcg_data); =20 - /* - * The lowest bit set means that memcg isn't a valid - * memcg pointer, but a obj_cgroups pointer. - * In this case the page is shared and doesn't belong - * to any specific memory cgroup. - */ - if (memcg_data & 0x1UL) + if (memcg_data & MEMCG_DATA_OBJCGS) return NULL; =20 return (struct mem_cgroup *)memcg_data; @@ -429,7 +432,11 @@ static inline struct mem_cgroup *page_memcg_check(st= ruct page *page) */ static inline struct obj_cgroup **page_objcgs(struct page *page) { - return (struct obj_cgroup **)(READ_ONCE(page->memcg_data) & ~0x1UL); + unsigned long memcg_data =3D READ_ONCE(page->memcg_data); + + VM_BUG_ON_PAGE(memcg_data && !(memcg_data & MEMCG_DATA_OBJCGS), page); + + return (struct obj_cgroup **)(memcg_data & ~MEMCG_DATA_FLAGS_MASK); } =20 /* @@ -444,10 +451,10 @@ static inline struct obj_cgroup **page_objcgs_check= (struct page *page) { unsigned long memcg_data =3D READ_ONCE(page->memcg_data); =20 - if (memcg_data && (memcg_data & 0x1UL)) - return (struct obj_cgroup **)(memcg_data & ~0x1UL); + if (!memcg_data || !(memcg_data & MEMCG_DATA_OBJCGS)) + return NULL; =20 - return NULL; + return (struct obj_cgroup **)(memcg_data & ~MEMCG_DATA_FLAGS_MASK); } =20 /* @@ -460,7 +467,8 @@ static inline struct obj_cgroup **page_objcgs_check(s= truct page *page) static inline bool set_page_objcgs(struct page *page, struct obj_cgroup **objcgs) { - return !cmpxchg(&page->memcg_data, 0, (unsigned long)objcgs | 0x1UL); + return !cmpxchg(&page->memcg_data, 0, (unsigned long)objcgs | + MEMCG_DATA_OBJCGS); } #else static inline struct obj_cgroup **page_objcgs(struct page *page) --=20 2.26.2