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=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 DFD71C47420 for ; Tue, 29 Sep 2020 23:59:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8FB15206DC for ; Tue, 29 Sep 2020 23:59:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="nhh5fkjo" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729179AbgI2X73 (ORCPT ); Tue, 29 Sep 2020 19:59:29 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:13146 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728895AbgI2X72 (ORCPT ); Tue, 29 Sep 2020 19:59:28 -0400 Received: from pps.filterd (m0148460.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 08TNtgXM016420 for ; Tue, 29 Sep 2020 16:59:27 -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=J3JR/fo4mVtkbf3ybeD8TyHNRNb5BoObkpsNWSI6exs=; b=nhh5fkjoZgKPAycr7N4o4xOVqCF0Tfup2AtjEOr4aq/HFmscdgDw00XYiDErq6E55o0w ZNrvzu6f6L/CtL0m+c/OI3vmfJ/gbX+ociYuD71JM5QaJcSIcppMBlfeXxwslGFg01oR N7Iez9Cm6dLAiwtc3lWZuZlGpM977IpaC1k= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com with ESMTP id 33t35n875g-4 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Tue, 29 Sep 2020 16:59:27 -0700 Received: from intmgw002.41.prn1.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Tue, 29 Sep 2020 16:59:25 -0700 Received: by devvm1755.vll0.facebook.com (Postfix, from userid 111017) id 71211D62156; Tue, 29 Sep 2020 16:59:21 -0700 (PDT) From: Roman Gushchin To: Andrew Morton CC: Shakeel Butt , Johannes Weiner , Michal Hocko , , , , Roman Gushchin Subject: [PATCH v3 3/4] mm: introduce page memcg flags Date: Tue, 29 Sep 2020 16:59:19 -0700 Message-ID: <20200929235920.537849-4-guro@fb.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200929235920.537849-1-guro@fb.com> References: <20200929235920.537849-1-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=2020-09-29_14:2020-09-29,2020-09-29 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 mlxlogscore=356 mlxscore=0 lowpriorityscore=0 suspectscore=0 impostorscore=0 malwarescore=0 phishscore=0 clxscore=1015 bulkscore=0 priorityscore=1501 spamscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009290203 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 --- 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 d4d15c04bbaf..35f846c6b89b 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, + /* the next bit after the last actual flag */ + __NR_MEMCG_DATA_FLAGS, +}; + +#define MEMCG_DATA_FLAGS_MASK ((0x1UL << __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 & (0x1UL << MEMCG_DATA_OBJCGS)) return NULL; =20 return (struct mem_cgroup *)memcg_data; @@ -459,7 +462,12 @@ static inline void clear_page_memcg(struct page *pag= e) */ 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 & (0x1UL << MEMCG_DATA_OBJCGS)), page); + + return (struct obj_cgroup **)(memcg_data & ~MEMCG_DATA_FLAGS_MASK); } =20 /* @@ -474,8 +482,9 @@ 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 & (0x1UL << MEMCG_DATA_OBJCGS))) + return (struct obj_cgroup **) + (memcg_data & ~MEMCG_DATA_FLAGS_MASK); =20 return NULL; } @@ -490,7 +499,11 @@ 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 (0x1UL << MEMCG_DATA_OBJCGS); + + return !cmpxchg(&page->memcg_data, 0, memcg_data); } =20 /* --=20 2.26.2