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Wed, 24 Jul 2019 09:20:23 +0000 Received: from MWHPR15MB1165.namprd15.prod.outlook.com ([fe80::4066:b41c:4397:27b7]) by MWHPR15MB1165.namprd15.prod.outlook.com ([fe80::4066:b41c:4397:27b7%7]) with mapi id 15.20.2094.013; Wed, 24 Jul 2019 09:20:23 +0000 From: Song Liu To: Oleg Nesterov CC: lkml , "linux-mm@kvack.org" , "akpm@linux-foundation.org" , "matthew.wilcox@oracle.com" , "kirill.shutemov@linux.intel.com" , "peterz@infradead.org" , "rostedt@goodmis.org" , "Kernel Team" , "william.kucharski@oracle.com" Subject: Re: [PATCH v8 2/4] uprobe: use original page when all uprobes are removed Thread-Topic: [PATCH v8 2/4] uprobe: use original page when all uprobes are removed Thread-Index: AQHVQfsnepoAlMhPK0qmuIU0gpphb6bZeoCAgAACwICAAADTAA== Date: Wed, 24 Jul 2019 09:20:22 +0000 Message-ID: <58E13FCB-FE49-454F-995F-832870D314F1@fb.com> References: <20190724083600.832091-1-songliubraving@fb.com> <20190724083600.832091-3-songliubraving@fb.com> <20190724090734.GB21599@redhat.com> <20190724091725.GC21599@redhat.com> In-Reply-To: <20190724091725.GC21599@redhat.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-mailer: Apple Mail (2.3445.104.11) x-originating-ip: [2620:10d:c090:180::1:87bf] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 9695b7be-769c-4abf-3145-08d7101827fb x-microsoft-antispam: BCL:0;PCL:0;RULEID:(2390118)(7020095)(4652040)(8989299)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(5600148)(711020)(4605104)(1401327)(2017052603328)(7193020);SRVR:MWHPR15MB1437; 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charset="us-ascii" Content-ID: <4AC5CABC203ED5468A8A27501B4B6F6F@namprd15.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: 9695b7be-769c-4abf-3145-08d7101827fb X-MS-Exchange-CrossTenant-originalarrivaltime: 24 Jul 2019 09:20:22.8454 (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: songliubraving@fb.com X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR15MB1437 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-07-24_03:,, 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=682 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1907240103 X-FB-Internal: deliver Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Jul 24, 2019, at 2:17 AM, Oleg Nesterov wrote: >=20 > On 07/24, Oleg Nesterov wrote: >>=20 >> On 07/24, Song Liu wrote: >>>=20 >>> This patch allows uprobe to use original page when possible (all uprobe= s >>> on the page are already removed). >>=20 >> and only if the original page is already in the page cache and uptodate, >> right? >>=20 >> another reason why I think unmap makes more sense... but I won't argue. >=20 > but somehow I forgot we need to read the original page anyway to check > pages_identical(), so unmap is not really better, please forget. >=20 Yeah, I was trying to explain this. :) Thanks for your feedbacks.=20 Song