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Mon, 29 Jul 2019 17:04:05 +0000 Received: from MWHPR15MB1165.namprd15.prod.outlook.com ([fe80::d4fc:70c0:79a5:f41b]) by MWHPR15MB1165.namprd15.prod.outlook.com ([fe80::d4fc:70c0:79a5:f41b%2]) with mapi id 15.20.2115.005; Mon, 29 Jul 2019 17:04:05 +0000 From: Song Liu To: Oleg Nesterov CC: Andrew Morton , "Kirill A. Shutemov" , Matthew Wilcox , Peter Zijlstra , "Steven Rostedt" , Srikar Dronamraju , William Kucharski , "linux-kernel@vger.kernel.org" Subject: Re: + uprobe-use-original-page-when-all-uprobes-are-removed.patch added to -mm tree Thread-Topic: + uprobe-use-original-page-when-all-uprobes-are-removed.patch added to -mm tree Thread-Index: AQHVRAZeDd93yJdBykiPoGv83wMqwKbhth4AgAAhFoA= Date: Mon, 29 Jul 2019 17:04:05 +0000 Message-ID: <40C3ABEE-B1D1-445B-9637-A2BD5ED9C316@fb.com> References: <20190726230333.drvM6x-wz%akpm@linux-foundation.org> <20190729150539.GB11349@redhat.com> In-Reply-To: <20190729150539.GB11349@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:c090:200::2:d148] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 9159fbf7-54ee-4bf0-0c5b-08d71446c3a4 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; x-ms-traffictypediagnostic: MWHPR15MB1437: x-ms-exchange-purlcount: 1 x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:5516; x-forefront-prvs: 01136D2D90 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(346002)(376002)(396003)(39860400002)(136003)(366004)(189003)(199004)(11346002)(8936002)(54906003)(53936002)(99286004)(6246003)(8676002)(6306002)(50226002)(6512007)(6116002)(71200400001)(71190400001)(6436002)(305945005)(7736002)(229853002)(33656002)(4326008)(81156014)(6916009)(81166006)(486006)(316002)(966005)(256004)(6486002)(57306001)(36756003)(76176011)(46003)(25786009)(86362001)(186003)(102836004)(76116006)(66556008)(64756008)(66446008)(66476007)(66946007)(14454004)(2906002)(2616005)(476003)(5660300002)(446003)(478600001)(68736007)(6506007)(53546011);DIR:OUT;SFP:1102;SCL:1;SRVR:MWHPR15MB1437;H:MWHPR15MB1165.namprd15.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;MX:1;A:1; received-spf: None (protection.outlook.com: fb.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam-message-info: ybQVq+a4aytbVU1H4R9BA3G+jtXd2D8PIzuA6eHwQcKoba0cqWSImMTZ+wact26ZstCXFGe3c5VNv2pLOuB4ZXWTfwoxgRVNsscRY6phGZ1Xf9NqBz3Twh0WR6FFyZ8jJCoHTEEPc092gG967EbTndIRboIs6uK12gotx5hm0Pzv9XsRUjNxbxzh5MXHWC5UVpkRW8r+uQWIoyfJNfb2KiWl44wBLr4YdBeclKEhpOKq1HnQBJkjziaMt6du9QFegJLeY9j9obqG6oKdlPNEfbGy/DMYLReWz6tt9pGEYq39mbP5vlRhXZ487byKRLbipes2QEYe4DeEMk25MHJqipT909xA33Am0lc5nERlA4fsajXkgjoFBmkCPmTmAcXeiD3e4MU4J5JdYxogcwbaIJwVTrwqW4TibIzzSA/DeBs= Content-Type: text/plain; charset="us-ascii" Content-ID: <6FA930A341F76D4EBDC5AE1B1EB645B9@namprd15.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: 9159fbf7-54ee-4bf0-0c5b-08d71446c3a4 X-MS-Exchange-CrossTenant-originalarrivaltime: 29 Jul 2019 17:04:05.7467 (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=2019-07-29_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=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1907290187 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 29, 2019, at 8:05 AM, Oleg Nesterov wrote: >=20 > I didn't see this version, so let me reply here. >=20 > On 07/26, Andrew Morton wrote: >>=20 >> + /* try orig_page only for unregister and anonymous old_page */ >> + if (!is_register && PageAnon(old_page)) { >=20 > Well, this is confusing... nothing really wrong, but we certainly do not > want to install the new anonymous page if !is_register && !PageAnon(old). > And in this case we do not even want to call __replace page(). >=20 > OK, I won't insist, this should almost never happen, but again, please > see https://lore.kernel.org/lkml/20190726084423.GA16112@redhat.com/ I see. Do you want me fold this patch with 2/4?=20 >=20 >> + struct page *orig_page; >> + pgoff_t index; >> + >> + index =3D vaddr_to_offset(vma, vaddr & PAGE_MASK) >> PAGE_SHIFT; >> + orig_page =3D find_get_page(vma->vm_file->f_inode->i_mapping, >> + index); >> + >> + if (orig_page) { >> + if (PageUptodate(orig_page) && >> + pages_identical(new_page, orig_page)) { >> + /* let go new_page */ >> + put_page(new_page); >> + new_page =3D NULL; >> + >> + /* dec_mm_counter for old_page */ >> + dec_mm_counter(mm, MM_ANONPAGES); >=20 > this assumes that __replace_page() can't fail, but it can. I think you > should move this into into __replace_page(). Good catch! Let me fix it.=20 Hi Andrew, Do you prefer a whole v10 (1/4 to 4/4) or just newer version of this=20 one (2/4)? Thanks, Song=20