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Tue, 3 Nov 2020 21:30:17 +0000 Date: Tue, 3 Nov 2020 13:30:10 -0800 From: Roman Gushchin To: Michal Hocko CC: Johannes Weiner , Michal =?iso-8859-1?Q?Koutn=FD?= , Richard Palethorpe , , Andrew Morton , Shakeel Butt , Christoph Lameter , Tejun Heo , Vlastimil Babka , , Subject: Re: [RFC PATCH] mm: memcg/slab: Stop reparented obj_cgroups from charging root Message-ID: <20201103213010.GA1938922@carbon.dhcp.thefacebook.com> References: <20201014190749.24607-1-rpalethorpe@suse.com> <20201016094702.GA95052@blackbook> <20201016145308.GA312010@cmpxchg.org> <20201016171502.GA102311@blackbook> <20201019222845.GA64774@carbon.dhcp.thefacebook.com> <20201020162714.GC46039@blackbook> <20201020170717.GA153102@carbon.DHCP.thefacebook.com> <20201020181822.GA397401@cmpxchg.org> <20201021193322.GA300658@carbon.dhcp.thefacebook.com> <20201103132221.GI21990@dhcp22.suse.cz> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201103132221.GI21990@dhcp22.suse.cz> X-Originating-IP: [2620:10d:c090:400::5:6cce] X-ClientProxiedBy: MWHPR13CA0022.namprd13.prod.outlook.com (2603:10b6:300:16::32) 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::5:6cce) by MWHPR13CA0022.namprd13.prod.outlook.com (2603:10b6:300:16::32) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3541.10 via Frontend Transport; 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X-MS-Exchange-AntiSpam-MessageData: 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 X-MS-Exchange-CrossTenant-Network-Message-Id: a8810314-e3eb-4bf9-68bd-08d8803fa857 X-MS-Exchange-CrossTenant-AuthSource: BYAPR15MB4136.namprd15.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Nov 2020 21:30:17.0719 (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: g8ggpXwjuVTy6k6lPOTM5Vh5J3y1ADGNABL6xkq7j81HlMupoOCaPuItL5vHNYwq X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR15MB3445 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.312,18.0.737 definitions=2020-11-03_14:2020-11-03,2020-11-03 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 adultscore=0 spamscore=0 clxscore=1015 phishscore=0 impostorscore=0 mlxscore=0 mlxlogscore=999 suspectscore=1 priorityscore=1501 malwarescore=0 bulkscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2011030142 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 Tue, Nov 03, 2020 at 02:22:21PM +0100, Michal Hocko wrote: > Hi, > I am sorry but I was quite busy at the time this has been discussed. > Now that I got to this thread finally I am wondering whether this > resp. other root cgroup exceptions have any follow up. I'll address a feedback I've got from Johannes and will post and updated version soon. > > I have seen the issue is fixed in Linus tree by 8de15e920dc8 ("mm: > memcg: link page counters to root if use_hierarchy is false"). Thanks > for taking care of that! I do agree that this approach is the most > reasonable immediate fix. Thanks! > > Btw. we have been carrying a warning about non hierarchical hierarchies > for years in our distribution kernels and haven't heard of any actual > bug reports (except for LTP driven ones). So we might be really close to > simply drop this functionality completely. This would simplify the code > and prevent from future surprises. Just sent an rfc patchset. Your feedback will be greatly appreciated! Thanks!