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Tue, 23 Jan 2018 23:16:08 -0500 Received: from mail-by2nam03on0132.outbound.protection.outlook.com ([104.47.42.132]:45413 "EHLO NAM03-BY2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932493AbeAXEQF (ORCPT ); Tue, 23 Jan 2018 23:16:05 -0500 From: Sasha Levin To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" CC: Jiang Biao , Al Viro , Minchan Kim , Michal Hocko , "zhong.weidong@zte.com.cn" , Andrew Morton , Linus Torvalds , Sasha Levin Subject: [PATCH AUTOSEL for 4.14 077/100] fs/mbcache.c: make count_objects() more robust Thread-Topic: [PATCH AUTOSEL for 4.14 077/100] fs/mbcache.c: make count_objects() more robust Thread-Index: AQHTlMnp9NeFjVVSqk+V0LdhDJLMnQ== Date: Wed, 24 Jan 2018 04:15:04 +0000 Message-ID: <20180124041414.32065-77-alexander.levin@microsoft.com> References: <20180124041414.32065-1-alexander.levin@microsoft.com> In-Reply-To: <20180124041414.32065-1-alexander.levin@microsoft.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [52.168.54.252] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;DM5PR2101MB1078;7:/SYGYbvWAPnt9qqRG0lKWzKVwl0d2IKzW7QX3b5+K91ISU6Jb2k8qdQ1jATIKTqK722a9NTjlPAQotbFdl+oJVWuol5jgO279Bw8qH0lYx1R+KWsGQT8AYEpMub7Ms/itbEZ5mUkM7CjbRs+N6upOnvMOrmhEx79G6ztf6QnDnLUFq3q+g6rS0RWZ+EorAqQCE1JSsbrkQgfCeM9vxR75PrbU8NeH20k4ZHM7r+T1xY5vkUOpglDTUXq2M3oSRKS x-ms-office365-filtering-correlation-id: e062a10b-89af-45a6-12a9-08d562e12cca x-ms-office365-filtering-ht: Tenant x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(5600026)(4604075)(3008032)(4534165)(4627221)(201703031133081)(201702281549075)(48565401081)(2017052603307)(7193020);SRVR:DM5PR2101MB1078; 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authentication-results: spf=none (sender IP is ) smtp.mailfrom=Alexander.Levin@microsoft.com; x-microsoft-antispam-message-info: cHxDqt5DhRSfSyUOEXTpWI0+Nl8QAEyUzRlcFdm1LKgB+lYHLUEtez/RvIrhDCJ9M5zybxbXj7Kxr9LBOnAJNw== spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-Network-Message-Id: e062a10b-89af-45a6-12a9-08d562e12cca X-MS-Exchange-CrossTenant-originalarrivaltime: 24 Jan 2018 04:15:04.9926 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR2101MB1078 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: From: Jiang Biao [ Upstream commit d5dabd633922ac5ee5bcc67748f7defb8b211469 ] When running ltp stress test for 7*24 hours, vmscan occasionally emits the following warning continuously: mb_cache_scan+0x0/0x3f0 negative objects to delete nr=3D-9232265467809300450 ... Tracing shows the freeable(mb_cache_count returns) is -1, which causes the continuous accumulation and overflow of total_scan. This patch makes sure that mb_cache_count() cannot return a negative value, which makes the mbcache shrinker more robust. Link: http://lkml.kernel.org/r/1511753419-52328-1-git-send-email-jiang.biao= 2@zte.com.cn Signed-off-by: Jiang Biao Cc: Al Viro Cc: Minchan Kim Cc: Michal Hocko Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- fs/mbcache.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/mbcache.c b/fs/mbcache.c index d818fd236787..b8b8b9ced9f8 100644 --- a/fs/mbcache.c +++ b/fs/mbcache.c @@ -269,6 +269,9 @@ static unsigned long mb_cache_count(struct shrinker *sh= rink, struct mb_cache *cache =3D container_of(shrink, struct mb_cache, c_shrink); =20 + /* Unlikely, but not impossible */ + if (unlikely(cache->c_entry_count < 0)) + return 0; return cache->c_entry_count; } =20 --=20 2.11.0