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Thu, 29 Oct 2020 00:16:39 +0000 Date: Wed, 28 Oct 2020 17:16:35 -0700 From: Roman Gushchin To: Muchun Song CC: , , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH v2] mm: memcg/slab: Fix return child memcg objcg for root memcg Message-ID: <20201029001635.GG827280@carbon.dhcp.thefacebook.com> References: <20201028035013.99711-1-songmuchun@bytedance.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201028035013.99711-1-songmuchun@bytedance.com> X-Originating-IP: [2620:10d:c090:400::4:cadf] X-ClientProxiedBy: BYAPR01CA0034.prod.exchangelabs.com (2603:10b6:a02:80::47) 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::4:cadf) by BYAPR01CA0034.prod.exchangelabs.com (2603:10b6:a02:80::47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3499.19 via Frontend Transport; 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X-MS-Exchange-AntiSpam-MessageData: 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 X-MS-Exchange-CrossTenant-Network-Message-Id: bfcc79a1-fe17-4d35-57f5-08d87b9fe7cc X-MS-Exchange-CrossTenant-AuthSource: BYAPR15MB4136.namprd15.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 Oct 2020 00:16:39.4768 (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: zJmntRJQQ1qTSMTYJRvZSqjy/Lya1mJmievTlEt2gLCORk/1F5mL9HpaB4XNgh3s X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR15MB2486 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.312,18.0.737 definitions=2020-10-28_09:2020-10-28,2020-10-28 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 suspectscore=1 bulkscore=0 phishscore=0 mlxscore=0 adultscore=0 mlxlogscore=873 spamscore=0 malwarescore=0 lowpriorityscore=0 impostorscore=0 clxscore=1015 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2010280151 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 28, 2020 at 11:50:10AM +0800, Muchun Song wrote: > Consider the following memcg hierarchy. > > root > / \ > A B > > If we get the objcg of memcg A failed, the get_obj_cgroup_from_current > can return the wrong objcg for the root memcg. > > Fixes: bf4f059954dc ("mm: memcg/slab: obj_cgroup API") > Signed-off-by: Muchun Song Acked-by: Roman Gushchin Thanks!