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=-13.6 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=ham 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 7043EC4363D for ; Thu, 1 Oct 2020 00:27:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2ACAB206B6 for ; Thu, 1 Oct 2020 00:27:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="efLaWR9l" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732021AbgJAA1Y (ORCPT ); Wed, 30 Sep 2020 20:27:24 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:63106 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731915AbgJAA1X (ORCPT ); Wed, 30 Sep 2020 20:27:23 -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 0910QS08029753 for ; Wed, 30 Sep 2020 17:27:22 -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=dpxtskcYy2IkajGXOLE8b65py0lMSTMcjWtCzd6f9dY=; b=efLaWR9ljHfMH5Pl3RQHXtqbQsWhYxNTyWt6iYxQcp0d2qllX1K4Nsa1xdE2anPm6Zx1 dADG/Z75emros7uXWfQZ8PIf5aGwyGRvCiBVgtB2vNZRJbHYmTbHJYsJia5k/3pKusmN Pjng3XWmc98pvU2RK45NwncSLyFPzBOgQK8= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com with ESMTP id 33vtgc3pqb-6 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Wed, 30 Sep 2020 17:27:22 -0700 Received: from intmgw002.41.prn1.facebook.com (2620:10d:c085:208::f) by mail.thefacebook.com (2620:10d:c085:11d::4) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Wed, 30 Sep 2020 17:27:21 -0700 Received: by devvm1755.vll0.facebook.com (Postfix, from userid 111017) id CD2D2DE966B; Wed, 30 Sep 2020 17:27:17 -0700 (PDT) From: Roman Gushchin To: Andrew Morton CC: Shakeel Butt , Johannes Weiner , Michal Hocko , , , , Roman Gushchin Subject: [PATCH v4 3/4] mm: introduce page memcg flags Date: Wed, 30 Sep 2020 17:27:09 -0700 Message-ID: <20201001002710.748166-4-guro@fb.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20201001002710.748166-1-guro@fb.com> References: <20201001002710.748166-1-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=2020-09-30_13:2020-09-30,2020-09-30 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 spamscore=0 bulkscore=0 lowpriorityscore=0 suspectscore=0 impostorscore=0 phishscore=0 adultscore=0 priorityscore=1501 malwarescore=0 mlxlogscore=406 mlxscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2010010002 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 --- include/linux/memcontrol.h | 35 ++++++++++++++++++++++++----------- 1 file changed, 24 insertions(+), 11 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 7e3da7cdc1ba..5e05599e1f74 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; @@ -448,7 +451,12 @@ static inline void set_page_memcg(struct page *page,= struct mem_cgroup *memcg) */ 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 /* @@ -463,8 +471,9 @@ static inline struct obj_cgroup **page_objcgs_check(s= truct 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 (struct obj_cgroup **) + (memcg_data & ~MEMCG_DATA_FLAGS_MASK); =20 return NULL; } @@ -479,7 +488,11 @@ static inline struct obj_cgroup **page_objcgs_check(= struct 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); + unsigned long memcg_data =3D (unsigned long)objcgs; + + memcg_data |=3D MEMCG_DATA_OBJCGS; + + return !cmpxchg(&page->memcg_data, 0, memcg_data); } #else static inline struct obj_cgroup **page_objcgs(struct page *page) --=20 2.26.2