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=-3.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, T_DKIMWL_WL_HIGH,T_DKIMWL_WL_MED,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 16ED4C4321D for ; Tue, 21 Aug 2018 21:36:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A9CEE2147C for ; Tue, 21 Aug 2018 21:36:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="DGg+vclb"; dkim=pass (1024-bit key) header.d=fb.onmicrosoft.com header.i=@fb.onmicrosoft.com header.b="Lgq7d7uW" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A9CEE2147C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=fb.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727705AbeHVA6r (ORCPT ); Tue, 21 Aug 2018 20:58:47 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:50328 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726626AbeHVA6r (ORCPT ); Tue, 21 Aug 2018 20:58:47 -0400 Received: from pps.filterd (m0148460.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w7LLYGVf010571; Tue, 21 Aug 2018 14:36:25 -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-type; s=facebook; bh=AtNuxCAd7TECN28SamN4dQlQrOCShOwPTHfKehhUkiY=; b=DGg+vclb8Efw0NXz5xBuHbfrNiteeGUPQL7H8PG02tFFC5w/1by8xyc5mw2N7GhzJvVH LCe3Q4Q6cHDf/4ll3BlSd37urE/oJBQzSZHgg8UeCSCFmTnCurCcvLcGfHCLsB2g/gPw WUU0xDVFfxZJTLRFJBJZck5ZvSg+qnnH7J8= Received: from maileast.thefacebook.com ([199.201.65.23]) by mx0a-00082601.pphosted.com with ESMTP id 2m0ssj05sg-1 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT); Tue, 21 Aug 2018 14:36:24 -0700 Received: from NAM03-CO1-obe.outbound.protection.outlook.com (192.168.183.28) by o365-in.thefacebook.com (192.168.177.29) with Microsoft SMTP Server (TLS) id 14.3.361.1; Tue, 21 Aug 2018 17:36:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.onmicrosoft.com; s=selector1-fb-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=AtNuxCAd7TECN28SamN4dQlQrOCShOwPTHfKehhUkiY=; b=Lgq7d7uWgarELyI34TnUPnI2stRSMm4W9mKIh4PRGBJjiLf5hLuMGIgPc6Yer3kPKdDSLXc5ZI6f5KqFh3BKdWEcRbTaCHvPi21Hkj8Euu3i3qLNe1tWtVGBLa9xSadZMAYh+wCEGjIFCE97roxL3bJR9gF08WXNtdNKpTwHBq0= Received: from tower.thefacebook.com (2620:10d:c090:200::7:b0bf) by BY2PR15MB0166.namprd15.prod.outlook.com (2a01:111:e400:58e0::12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.1038.23; Tue, 21 Aug 2018 21:36:17 +0000 From: Roman Gushchin To: CC: , , Roman Gushchin , Andrew Morton , Johannes Weiner , Michal Hocko , Tejun Heo , Rik van Riel , Konstantin Khlebnikov , Matthew Wilcox Subject: [PATCH v2 3/3] mm: don't miss the last page because of round-off error Date: Tue, 21 Aug 2018 14:35:59 -0700 Message-ID: <20180821213559.14694-3-guro@fb.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180821213559.14694-1-guro@fb.com> References: <20180821213559.14694-1-guro@fb.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [2620:10d:c090:200::7:b0bf] X-ClientProxiedBy: MWHPR1301CA0004.namprd13.prod.outlook.com (2603:10b6:301:29::17) To BY2PR15MB0166.namprd15.prod.outlook.com (2a01:111:e400:58e0::12) X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: d642fca3-da94-4a09-ca7f-08d607ae2110 X-Microsoft-Antispam: BCL:0;PCL:0;RULEID:(7020095)(4652040)(8989137)(4534165)(4627221)(201703031133081)(201702281549075)(8990107)(5600074)(711020)(2017052603328)(7153060)(7193020);SRVR:BY2PR15MB0166; X-Microsoft-Exchange-Diagnostics: 1;BY2PR15MB0166;3:LIBr+b21RooN9jRroTXs615jOiIuFKiW+AnvWZcTWQk1CZM8WocHJde+ADyH39Mm7+bFfWZmo7gcY3VfEy6yacHVHLh0U3zmQNDOYvpHAmNC20TYufAFxo9rRAFxKSYsx5PShqRaIVOwOZ9Rkc1vzLuyyizFzH9IMJ/g9IH3B2okbITxvzeYeak22o4myQAObGjlRWss6CUubQNkXA+oNgRzFsFpGyHuUL/bDtCJctwOfpHWQaG2J9Svf8MRyWQy;25:XWtKi1pOzsSvDscwOwVf21Ar/6gs1YH6QC9s6Dc2PWr2n1tqS0czPmaGtmcGqlELgcFY7i95lEdrrghgY6L3JysrtVcKDUJu2Mpe/DJjGGMmLXeUSBVALAuAje08A0suCXaKmUPW+DNZWp6vDlulVn/sSOqfeA5Uww8kX1Tyav1zwTXouCc0yqq1nJt5C5AVkT5y5xmIlZmkBtdbZwx+Q7TgKAu9L46FIGTmJjm44mFCfw0sz8lYGYxr1KSkksP+wXvtklUucscgxvYoX64yT3CZST52dloDdmYeSx1JuVRyInSu/OGc+qigAXdJD9b8/foKmJYmQWtWT+NEIusBag==;31:ZVL8h2o8SHYz40lFhG6k7z29gRsezh9UhvaVA940Bhi7aE/VIFdicJf8JSHXB490f9uFdKccTrC6rPxs+g4fxryZrcvnNWytrO9h5NTw0KAxg+Q8rMOpTkhUBL4BBr6yW17grtx9H0s+2OoIRYaURHalYA1a4SW5NGETqkPHl37/fMp2xK0tSb42i663p+5BVT8EqsSEy8ak+E+SacGZZr+YAe6gUdbYDRje8l1L9p8= X-MS-TrafficTypeDiagnostic: BY2PR15MB0166: X-Microsoft-Exchange-Diagnostics: 1;BY2PR15MB0166;20: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;4:EOjS/smeJd1k98sbq9ecI8oer0bxN4DadOT2HlQtXGoF14dKeDa+x8scsGC/BAhhug8uQWycw3nm96imIg6pgBwYO/iebaF6u48u2L6LJpGd3+Gjazl4dGIxt2R2YozfeYzQ5/zR7G/dexQQ/XhJ4aklRoCBdHDq6VHLHz2Gda3hJ/YScm34cKr89LjZs4iZuA07mZMdIAU+zfIxGHg9Gul8d3mjjlodhI7pmfbJFL3eMvpD/9/daNox8K+YzeZFsMS/eYALywaaF8zjNAoF0SllGk9TuZ5VNHnXttkqh8nUIOxM8c0UenuwOJgkKRgPlyadQCpez5Mh33px6K7OHuEbjOTi+E+CEvYTHjMHDSo= X-Microsoft-Antispam-PRVS: X-Exchange-Antispam-Report-Test: UriScan:(85827821059158)(67672495146484); X-MS-Exchange-SenderADCheck: 1 X-Exchange-Antispam-Report-CFA-Test: BCL:0;PCL:0;RULEID:(8211001083)(6040522)(2401047)(5005006)(8121501046)(823301075)(93006095)(93001095)(3002001)(10201501046)(3231311)(11241501184)(944501410)(52105095)(149027)(150027)(6041310)(20161123562045)(20161123564045)(20161123560045)(20161123558120)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(201708071742011)(7699016);SRVR:BY2PR15MB0166;BCL:0;PCL:0;RULEID:;SRVR:BY2PR15MB0166; X-Forefront-PRVS: 0771670921 X-Forefront-Antispam-Report: SFV:NSPM;SFS:(10019020)(346002)(136003)(376002)(39860400002)(396003)(366004)(199004)(189003)(53936002)(68736007)(39060400002)(50226002)(8936002)(25786009)(1076002)(2906002)(6116002)(4326008)(476003)(486006)(86362001)(16526019)(97736004)(6506007)(186003)(386003)(46003)(2361001)(478600001)(105586002)(48376002)(50466002)(54906003)(446003)(106356001)(6486002)(2351001)(2616005)(11346002)(6916009)(76176011)(52396003)(305945005)(6512007)(8676002)(53416004)(69596002)(36756003)(16586007)(81156014)(47776003)(81166006)(316002)(52116002)(5660300001)(6666003)(7736002)(51416003)(32033001)(42262002);DIR:OUT;SFP:1102;SCL:1;SRVR:BY2PR15MB0166;H:tower.thefacebook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;A:1;MX:1; Received-SPF: None (protection.outlook.com: fb.com does not designate permitted sender hosts) X-Microsoft-Exchange-Diagnostics: =?us-ascii?Q?1;BY2PR15MB0166;23:y0hBRbMJzP+aNudL97O3T5kyvLzHJjmpSEXCS3DcZ?= =?us-ascii?Q?ALUZJgzhSCgQg9j1mA7BlGBEngDRouKde43EdX8k4oRLvCk3yY02i+4HrXwj?= =?us-ascii?Q?471NszSe/1X4hT2hkSMM+WdaHBG1zqYUi4uMsZLyNeeu2is7w/ZWMfQN8bCv?= =?us-ascii?Q?aLHJZSayEdxt5YwiEDNLUp4V5Ieg3xZqMKXJVQcpX8tz0zZYx9Yqct2QF5u/?= =?us-ascii?Q?GdtbSgQpKffccad+uZfC6omSv7rkreWBcfKdTE4tjgKBffR5x00PJXS5Wvhb?= =?us-ascii?Q?isSw89aVLdjdjqzovMXdE0Pu6QJ8jALtBHBDqlc0WEob87G7shprWHiJUFtM?= =?us-ascii?Q?A81Pg8VcDETtYps+uJNnu5G1bfGNrG5wqnxRCSKyvXyvsfat2YPYoRlfYfrM?= =?us-ascii?Q?FDjcUPYYdC0bWoEFs+e3YhQWIe/Es44B6bGy4/dlLaIK6U0vaj3IwaCwtGar?= =?us-ascii?Q?EbbmXh4qnOOISJcxDLtDN3NY8EXR+4q2/HO0pFviiqbNRWg+6KtkBxnILN9J?= =?us-ascii?Q?Udm7utGuhuANvM8Bur4Ppp9dBzyFlzUNjjq2doXyOi13tdCBAk6jfw2/g/ts?= =?us-ascii?Q?zozbLpf3rfDRabZ5Av49pI8v+c3e1M7h69P1SpxC7i2G8Md/s1IHwmavC1gi?= =?us-ascii?Q?bCN79nISe3Iy6WXZGnEem7O/PbCyjjuTt4AD0yPYAI5rih3tlqfifIvJ4K6C?= =?us-ascii?Q?b1fPYD/KmnGv+7y+ienOHlPFGc+bU+d+sRPvrt8I0jathsE0xwGxJ2cbobnh?= =?us-ascii?Q?mZ3j6bfxLm4r6d2uEvHJ2UtMPRkv8DuFiAQ4MNEC9Zb9Qj+MfSS54HYRd7vS?= =?us-ascii?Q?nQWfePP0/G09wOS//BgWbGkrPsTJIdscHGUFNhZSksQnRQQEVB+xVcQ5l9cK?= =?us-ascii?Q?PQctAwmK93kKFjes2lQQF9i4xjFxSTuaU6JHOkKsrVAVz86jrny9lfvMVPI8?= =?us-ascii?Q?AbwqgNzB325JWOyVQpjtv1dF13yw3OKWDQjnRwYJtVbTrJ2p1czC5nj8bEsu?= =?us-ascii?Q?usxru3OuboQWN5iJjRHAQBmi9Db/RF023H7Pw4rsrmVHOc1abQZ3wjnolJ9W?= =?us-ascii?Q?j7SrcKTefPg4U9ytMGwMzGj96rZ1fkIyE1vBDAueQG4sPKHrbIL1MKbT0dZS?= =?us-ascii?Q?m88rvzbrH/1DxygudM3sTDXESXofPFyCxkp0RIW+Drd9MeWMkrqpVCYElBfj?= =?us-ascii?Q?HDFOVXZ5iL5ZVL3TJIp5r1loJG7nPEufYIY6XRhIIJUYD+OxkwMlHZIsxCon?= =?us-ascii?Q?ST7iOSZ6KcEqk5E6f00ofIiKBPiD5588I/eqmf+hABEJXetN/az0G5jwmnHZ?= =?us-ascii?Q?HhiZYn+OCdCMSlIuH2D5uc=3D?= X-Microsoft-Antispam-Message-Info: lLZoO6CUS+IvXEWqzE2a0QtnqRqrK/nGorfQ5fou4s26qViR96FmMqLF637os8uC19GKDDCkzy7MrHE+ngFIvTGFlOdT7XlErSBT1QDHWJSfjzAGPhg92GeGG6IAoUb6Z5NLGCx2qxFR+adnmsVbyRej6j5CAyj6riCE+YIo7bbpdd030e3n84umvSO1aXku90LKLpLVO90b6I6sqjXilxZv3LnzIwn/RLN/2W+NeS5aszqCuQZ5Oa3vY0BFKCexTZWUaB0qNzaTfw2sAk/PLNd7ZHczahZh8RMf229RcXV71flOhRauDRb/1w+R/VLwzcPWlzP//5Yddh3IkHGwsiyQnom9WcpX0PdlRt3EbKc= X-Microsoft-Exchange-Diagnostics: 1;BY2PR15MB0166;6:Pja/BRbYDsCuHlrh3yJ1itmlY4CoLbSganc4Cx7ckF5U0hlqoFG5PbP802ndAJmUmvAiirCrLXL9JpK3WGWN6zx01tcgy9mxYvdoDx+gmpZ8J5FkP/wBy1kSEbBmgdsAg73Q+LQ6aaBoxdA7aS9u3ziHF7qfRfHNPDlH863xm3nix4ohS6IZymJ/izp/u4tBjkPX3h8tBg0XryCJd+ggb9Ex4wv9hbJmR0lVhBY98Ab/zOs7y6vS8K1Zopcvb2S/YlAIU+mx333SE455BUvx4tKTOWYmiTR+rxw/Km0SnJPOPMAj4RFZtdrZpdOtA+be7y6PVMBUMkWxamDtScWk9XjcPhqOiMYZCukzmhHE64TCD7x7RpHc3d8eVj9SNtvsdd5avZTY56+UgdtHdhT7BQnT7OrZKbW7wV8iSS7v0lkck3AT5Yo3aNN0+un5dLRMCBYN4MVAVcWclMQieWYkZA==;5:/KAa5zBKS9g8U/2n0OB8vVd2y0iQnsZhzY6ooXa9HBafJJQOQUPRZue9SCzjJIFuYYhs06EB32EYuu989QHUvRIa3JB402RzNC3k74M4MF3RPFXO9U/sOEA9zspqqVFk5M06W8nLc+l5l77ms0L6LR3ulEO/0vFA2biSssEVu7M=;7:mrS+4dl9ehYoUU77B5pmLc3SbxSj6zHC72hcf8tGifsM9da6LMAW0kD1o7hbXXfVHHxvOOpkHTocnBRcAFquO9UssvFaO4KYBibDWY+1ciKGnPvAvkjmZQj8O+6oGPxz/pzMoD1kUd8IbLyXZmJI6ieDZFs/qF3BXyXMmthkSJHZ3UfzI3uh3jUYtqI4GEER+bgi+VfZU5VwqfenZKCmfxRZnCv5Sev9uv6qb/DA596IRR9LJHUunRhuvuemVTwx SpamDiagnosticOutput: 1:99 SpamDiagnosticMetadata: NSPM X-Microsoft-Exchange-Diagnostics: 1;BY2PR15MB0166;20:EWokAItNE4ut026bbDHsbyZ5DRk6mePeiyLx/68KdmyPckPmFrCGm6Gzk+un71kunFzR48SxJSU5hEkjyOPhVf164cPbhKuNJtMRIQfqRf6jAoidczWnNproN0ITuqlyn19+WvS44sd+bnLyFmOkYo2cH/Ryzs1/5vgLMUD31BQ= X-MS-Exchange-CrossTenant-OriginalArrivalTime: 21 Aug 2018 21:36:17.3081 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: d642fca3-da94-4a09-ca7f-08d607ae2110 X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY2PR15MB0166 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-08-21_09:,, signatures=0 X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I've noticed, that dying memory cgroups are often pinned in memory by a single pagecache page. Even under moderate memory pressure they sometimes stayed in such state for a long time. That looked strange. My investigation showed that the problem is caused by applying the LRU pressure balancing math: scan = div64_u64(scan * fraction[lru], denominator), where denominator = fraction[anon] + fraction[file] + 1. Because fraction[lru] is always less than denominator, if the initial scan size is 1, the result is always 0. This means the last page is not scanned and has no chances to be reclaimed. Fix this by rounding up the result of the division. In practice this change significantly improves the speed of dying cgroups reclaim. Signed-off-by: Roman Gushchin Cc: Andrew Morton Cc: Johannes Weiner Cc: Michal Hocko Cc: Tejun Heo Cc: Rik van Riel Cc: Konstantin Khlebnikov Cc: Matthew Wilcox --- include/linux/math64.h | 2 ++ mm/vmscan.c | 6 ++++-- 2 files changed, 6 insertions(+), 2 deletions(-) diff --git a/include/linux/math64.h b/include/linux/math64.h index 837f2f2d1d34..94af3d9c73e7 100644 --- a/include/linux/math64.h +++ b/include/linux/math64.h @@ -281,4 +281,6 @@ static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 divisor) } #endif /* mul_u64_u32_div */ +#define DIV64_U64_ROUND_UP(ll, d) div64_u64((ll) + (d) - 1, (d)) + #endif /* _LINUX_MATH64_H */ diff --git a/mm/vmscan.c b/mm/vmscan.c index 4375b1e9bd56..2d78c5cff15e 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2445,9 +2445,11 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg, /* * Scan types proportional to swappiness and * their relative recent reclaim efficiency. + * Make sure we don't miss the last page + * because of a round-off error. */ - scan = div64_u64(scan * fraction[file], - denominator); + scan = DIV64_U64_ROUND_UP(scan * fraction[file], + denominator); break; case SCAN_FILE: case SCAN_ANON: -- 2.17.1