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b=sqDDI34Xf6D+TNcefuxk0abSIi/v/ggd9t2NnES6pf4kbDSfkP0H3TcEP7KWMJz9bl0RA9TpKRWzHN0MdOK1p3nIJrL+FNVGv67W/UQPiimfw8tEB4L86HY/v0KgU4fnKWzdnpUWbvexMCCkLQmWf/XWEBogVi4JVyQnj8/7AEU= Received: from BY3PR05MB8531.namprd05.prod.outlook.com (2603:10b6:a03:3ce::6) by SJ2PR05MB10355.namprd05.prod.outlook.com (2603:10b6:a03:55c::13) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6699.27; Thu, 24 Aug 2023 15:28:54 +0000 Received: from BY3PR05MB8531.namprd05.prod.outlook.com ([fe80::f967:2d39:e36d:d1fa]) by BY3PR05MB8531.namprd05.prod.outlook.com ([fe80::f967:2d39:e36d:d1fa%6]) with mapi id 15.20.6699.027; Thu, 24 Aug 2023 15:28:54 +0000 From: Nadav Amit To: Qi Zheng CC: Andrew Morton , "david@fromorbit.com" , "tkhai@ya.ru" , "vbabka@suse.cz" , "roman.gushchin@linux.dev" , "djwong@kernel.org" , "brauner@kernel.org" , "Paul E. McKenney" , "tytso@mit.edu" , "steven.price@arm.com" , "cel@kernel.org" , "senozhatsky@chromium.org" , "yujie.liu@intel.com" , Greg Kroah-Hartman , Muchun Song , Linux Kernel Mailing List , linux-mm , "linux-fsdevel@vger.kernel.org" , Muchun Song , Pv-drivers , Arnd Bergmann Subject: Re: [PATCH v5 27/45] vmw_balloon: dynamically allocate the vmw-balloon shrinker Thread-Topic: [PATCH v5 27/45] vmw_balloon: dynamically allocate the vmw-balloon shrinker Thread-Index: AQHZ1j3DBP2XCIqsAUaSNzyK4XzAG6/5ktmA Date: Thu, 24 Aug 2023 15:28:54 +0000 Message-ID: <2E63E088-10D8-4343-BB78-27D2ABFB95E7@vmware.com> References: <20230824034304.37411-1-zhengqi.arch@bytedance.com> <20230824034304.37411-28-zhengqi.arch@bytedance.com> In-Reply-To: <20230824034304.37411-28-zhengqi.arch@bytedance.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-mailer: Apple Mail (2.3731.700.6) x-ms-publictraffictype: Email x-ms-traffictypediagnostic: BY3PR05MB8531:EE_|SJ2PR05MB10355:EE_ x-ms-office365-filtering-correlation-id: 15abcf0f-43b0-4e37-9e65-08dba4b6d3b1 x-ld-processed: b39138ca-3cee-4b4a-a4d6-cd83d9dd62f0,ExtAddr x-ms-exchange-senderadcheck: 1 x-ms-exchange-antispam-relay: 0 x-microsoft-antispam: BCL:0; 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charset="us-ascii" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: vmware.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: BY3PR05MB8531.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 15abcf0f-43b0-4e37-9e65-08dba4b6d3b1 X-MS-Exchange-CrossTenant-originalarrivaltime: 24 Aug 2023 15:28:54.5481 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: b39138ca-3cee-4b4a-a4d6-cd83d9dd62f0 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: /j8yFkrOVOnFVQ7s04JYOEozCtqFI2D8AIKG4kcYPDaqkEdgig45PyucLrHtpG1NottR/7ZLxY4NniSatsxnHg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ2PR05MB10355 X-Stat-Signature: weif5kuotaureiftamrufp6addoqzc1s X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 586E8C0003 X-Rspam-User: X-HE-Tag: 1692890938-954333 X-HE-Meta: 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 U4wl0YmT ROQbRhrAwDdJ612QWYh9k/xsL1Y0HPbN9exJK6hcXnVlGjhy6AlfuugyKnDJo/454HvPKvTRDYfurD7zeaSPGpPn8GpGef7qxI2j8AY5u8HzyZsR4xiEQkbe5Du7Hy3hCnB1mCYEwV0id4/sRUaaN7kUo/Oz8oE2T5Lx9X1jQwrVltgG9fwFLAG8Wp/23paJ3PxVVElrfe54yg7ByaUMCQb3dYAvA9rI2MLe8dFWbPma7Kni/szLybYpBFuTjVqk37LhcPIsUnY/04ttWiq2JJ+vFnzKyl10rLz1RTiowSeJ6b6HRUIA0sOVJ2unZncwpTzUCOftApizLzwjoNml0/R6NkeQKUTc0uNkBTR/dlGOWHaA= 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 Aug 23, 2023, at 8:42 PM, Qi Zheng wrote: >=20 > In preparation for implementing lockless slab shrink, use new APIs to > dynamically allocate the vmw-balloon shrinker, so that it can be freed > asynchronously via RCU. Then it doesn't need to wait for RCU read-side > critical section when releasing the struct vmballoon. >=20 > And we can simply exit vmballoon_init() when registering the shrinker > fails. So the shrinker_registered indication is redundant, just remove it= . ... Ugh. We should have already moved to OOM notifier instead... > static void vmballoon_unregister_shrinker(struct vmballoon *b) > { > - if (b->shrinker_registered) > - unregister_shrinker(&b->shrinker); > - b->shrinker_registered =3D false; > + shrinker_free(b->shrinker); > } If the patch goes through another iteration, please add: b->shrinker =3D NULL; Not that this is a real issue, but I prefer it so in order to more easily identify UAF if the function is called elsewhere. Otherwise, LGTM. Thanks.