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Fri, 28 May 2021 16:22:50 +0000 Date: Fri, 28 May 2021 09:22:45 -0700 From: Roman Gushchin To: Ming Lei CC: Jan Kara , Tejun Heo , , , , Alexander Viro , Dennis Zhou , Dave Chinner , Subject: Re: [PATCH v5 2/2] writeback, cgroup: release dying cgwbs by switching attached inodes Message-ID: References: <20210526222557.3118114-1-guro@fb.com> <20210526222557.3118114-3-guro@fb.com> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: X-Originating-IP: [2620:10d:c090:400::5:fc1a] X-ClientProxiedBy: MWHPR1401CA0006.namprd14.prod.outlook.com (2603:10b6:301:4b::16) To BYAPR15MB4136.namprd15.prod.outlook.com (2603:10b6:a03:96::24) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from carbon.DHCP.thefacebook.com (2620:10d:c090:400::5:fc1a) by MWHPR1401CA0006.namprd14.prod.outlook.com (2603:10b6:301:4b::16) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4173.22 via Frontend Transport; Fri, 28 May 2021 16:22:49 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: d44e5827-286e-4478-b9a3-08d921f4d67a X-MS-TrafficTypeDiagnostic: BYAPR15MB3477: X-Microsoft-Antispam-PRVS: X-FB-Source: Internal X-MS-Oob-TLC-OOBClassifiers: OLM:6430; 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dkim=pass header.d=fb.com header.s=facebook header.b=orlYUHuV; dmarc=pass (policy=reject) header.from=fb.com; spf=pass (imf16.hostedemail.com: domain of "prvs=578262e678=guro@fb.com" designates 67.231.153.30 as permitted sender) smtp.mailfrom="prvs=578262e678=guro@fb.com" X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 9B44F8019E91 X-Stat-Signature: oumawe5aumkdpqzapocfk7zisu4zsmmp X-HE-Tag: 1622218966-562869 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, May 28, 2021 at 10:58:04AM +0800, Ming Lei wrote: > On Wed, May 26, 2021 at 03:25:57PM -0700, Roman Gushchin wrote: > > Asynchronously try to release dying cgwbs by switching clean attached > > inodes to the bdi's wb. It helps to get rid of per-cgroup writeback > > structures themselves and of pinned memory and block cgroups, which > > are way larger structures (mostly due to large per-cpu statistics > > data). It helps to prevent memory waste and different scalability > > problems caused by large piles of dying cgroups. > > > > A cgwb cleanup operation can fail due to different reasons (e.g. the > > cgwb has in-glight/pending io, an attached inode is locked or isn't > > clean, etc). In this case the next scheduled cleanup will make a new > > attempt. An attempt is made each time a new cgwb is offlined (in other > > words a memcg and/or a blkcg is deleted by a user). In the future an > > additional attempt scheduled by a timer can be implemented. > > > > Signed-off-by: Roman Gushchin > > --- > > fs/fs-writeback.c | 35 ++++++++++++++++++ > > include/linux/backing-dev-defs.h | 1 + > > include/linux/writeback.h | 1 + > > mm/backing-dev.c | 61 ++++++++++++++++++++++++++++++-- > > 4 files changed, 96 insertions(+), 2 deletions(-) > > > > Hello Roman, > > The following kernel panic is triggered by this patch: Hello Ming! Thank you for the report and for trying my patches! I think I know what it is and will fix in the next version. Thanks!