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Tue, 13 Aug 2019 00:30:10 +0000 Received: from DM6PR15MB2635.namprd15.prod.outlook.com ([fe80::d1fc:b5c5:59a1:bd7e]) by DM6PR15MB2635.namprd15.prod.outlook.com ([fe80::d1fc:b5c5:59a1:bd7e%3]) with mapi id 15.20.2157.022; Tue, 13 Aug 2019 00:30:10 +0000 From: Roman Gushchin To: Andrew Morton , "linux-mm@kvack.org" CC: Michal Hocko , Johannes Weiner , "linux-kernel@vger.kernel.org" , Kernel Team Subject: Re: [PATCH] mm: memcontrol: flush percpu vmevents before releasing memcg Thread-Topic: [PATCH] mm: memcontrol: flush percpu vmevents before releasing memcg Thread-Index: AQHVUWcJo041kAovIUqPQ99aFT9BKqb4ObQA Date: Tue, 13 Aug 2019 00:30:09 +0000 Message-ID: <20190813003006.GA2146@tower.dhcp.thefacebook.com> References: <20190812233754.2570543-1-guro@fb.com> In-Reply-To: <20190812233754.2570543-1-guro@fb.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-clientproxiedby: BYAPR05CA0032.namprd05.prod.outlook.com (2603:10b6:a03:c0::45) To DM6PR15MB2635.namprd15.prod.outlook.com (2603:10b6:5:1a6::24) x-ms-exchange-messagesentrepresentingtype: 1 x-originating-ip: [2620:10d:c090:200::1:ee94] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 508b7880-1240-4852-be0e-08d71f8565f9 x-microsoft-antispam: BCL:0;PCL:0;RULEID:(2390118)(7020095)(4652040)(8989299)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(5600148)(711020)(4605104)(1401327)(2017052603328)(7193020);SRVR:DM6PR15MB3339; 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charset="us-ascii" Content-ID: <320C88B52CE1B3408C22FE36DF00648C@namprd15.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: 508b7880-1240-4852-be0e-08d71f8565f9 X-MS-Exchange-CrossTenant-originalarrivaltime: 13 Aug 2019 00:30:09.9960 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: rdM22WiZt7FbNtHjvHeGOy7XEwd/Ig8gQUcPcal+HF6ppF5TmQWX4pLEPZ+VU6oi X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR15MB3339 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-08-12_09:,, signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=979 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1908130001 X-FB-Internal: deliver 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 Mon, Aug 12, 2019 at 04:37:54PM -0700, Roman Gushchin wrote: > Similar to vmstats, percpu caching of local vmevents leads to an > accumulation of errors on non-leaf levels. This happens because > some leftovers may remain in percpu caches, so that they are > never propagated up by the cgroup tree and just disappear into > nonexistence with on releasing of the memory cgroup. >=20 > To fix this issue let's accumulate and propagate percpu vmevents > values before releasing the memory cgroup similar to what we're > doing with vmstats. >=20 > Since on cpu hotplug we do flush percpu vmstats anyway, we can > iterate only over online cpus. Just to clarify: this patch should be placed on top of two other patches, which I sent a bit earlier today: 1) mm: memcontrol: flush percpu slab vmstats on kmem offlining 2) mm: memcontrol: flush percpu vmstats before releasing memcg Sorry for the inconvenience, I forgot about vmevents during working on the final version, and remembered too late. Thanks!