From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29DECC3DA7F for ; Sat, 10 Aug 2024 21:05:46 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6FE8F6B008A; Sat, 10 Aug 2024 17:05:45 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6AEB16B0092; Sat, 10 Aug 2024 17:05:45 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 527AB6B0095; Sat, 10 Aug 2024 17:05:45 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 2FE026B008A for ; Sat, 10 Aug 2024 17:05:45 -0400 (EDT) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id C14421A115D for ; Sat, 10 Aug 2024 21:05:44 +0000 (UTC) X-FDA: 82437567408.29.E21D5B1 Received: from NAM12-MW2-obe.outbound.protection.outlook.com (mail-mw2nam12on2068.outbound.protection.outlook.com [40.107.244.68]) by imf26.hostedemail.com (Postfix) with ESMTP id D5B50140018 for ; Sat, 10 Aug 2024 21:05:41 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=TEZbfHWB; spf=pass (imf26.hostedemail.com: domain of ziy@nvidia.com designates 40.107.244.68 as permitted sender) smtp.mailfrom=ziy@nvidia.com; arc=pass ("microsoft.com:s=arcselector10001:i=1"); dmarc=pass (policy=reject) header.from=nvidia.com ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1723323931; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=D8LzUzg2DvUYErN11v80jm1vDjlRQj4dqDiTQaEJkjg=; b=LFdjTCoAQzQAsDKu6QmdwRKQFStrtq7zwq+s1Tywv41EU9J1RRoBmOKUNnQfELpEI0Xupw 81MEk0Z2wOUY9H3NhtkZ457FHBSDL8jYROLEjjIYGxldwTt30Q95sH+4SDpctbb1GJ6cN6 MFjN8956EZrfIVeZaXB4+crIRM2cIRQ= ARC-Authentication-Results: i=2; imf26.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=TEZbfHWB; spf=pass (imf26.hostedemail.com: domain of ziy@nvidia.com designates 40.107.244.68 as permitted sender) smtp.mailfrom=ziy@nvidia.com; arc=pass ("microsoft.com:s=arcselector10001:i=1"); dmarc=pass (policy=reject) header.from=nvidia.com ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1723323931; a=rsa-sha256; cv=pass; b=Lky3CDB+BbKLZZNLck7R4twrv7ADIqUkQF+fFUIJJokHJfVDPbWO1Hrq9WitVqiy2yV1E4 lHvAjQB09N4rMDqO42/DzDJt2a4RbCimj+upb4ukadj2gJym0N1ju2zulT41/yOLLjByOq JSMfZzBaeFRcFjALFuT4Nxh18Buu79U= ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=jWt2uFO68kCuAyp07dJ6/BQ96eMNkGy/GnqHWKuV6XCD0G9+yBxtAVfdVsnPhB0UpKBfg3+c4CB95ep33N+4M95Yv32k188kRiWQFazOBimX3sYpyDpw6wcUGwyC5V4WB1N/4ZpgBrhcSV5U4/uuZKUPgKz/caexKTbLZGvRfGWhjh9D3RAIeQKMK1Qm2o0Oofc7WtiqVGDQmc3dLORvuWHWzpsX9+xb/VJzDFxJo/ecq23P4+9FpWHrG1/bxmBmuvklJrDVbWvIp/VaRRjJpGr+RuZH0hOmI6jDqCu8r/xBrSv94Yg5pDFmH5gOOByJdYCyftoQd/raYFAIAQwKxA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=D8LzUzg2DvUYErN11v80jm1vDjlRQj4dqDiTQaEJkjg=; b=F3tnDGXrl+tUzKuE9DeJ1fyA+JWCvSLZVOecTj+R4OZWOKFMmBGkBXula10OZc46IP/CwIxxgeF5Ol4h567ObRAzelws9dcKUUdhadX/CBYvgQw4qgEZ8XOULaHvIcdyO6QVQsGKSJNR1AgVC5PXUg+3LvQgD82i3Z2t2Nw7PjaIqXfW0BzfVsQNjA5gYHme1rQ0BgZgK0J/N9YiKcqn0YmDrQj36emHbzE0P6Aux6789+5XAcXkYqtcoP9JRfr4vuAvCDFVDxR/ULWdBlAOgDeYzuF8dqWUgMG2LdB0GRfNB784S2EiYid/wJ2qIvBfOQ+pmfuJm+xuE5g/BytGMg== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=nvidia.com; dmarc=pass action=none header.from=nvidia.com; dkim=pass header.d=nvidia.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=D8LzUzg2DvUYErN11v80jm1vDjlRQj4dqDiTQaEJkjg=; b=TEZbfHWB59PbHzrg/5+49CXnMM8rphUOmem/lp3qRYghnrM1XH4P3WCNV+Z87IlNBeQqpYyYAromiUpJ+SH0larXH1foGyj8VoJ+h1HpxvvWVdgb5a+dBZV1wkps3VVrOKvSyENhDA/xPteVa3ts+VygButWNt9oR2IbdLcSTr1Zk6rybyFerMyI48IcWSywjTeyU7pfFQaolrjPfmUArrUsS3rnD5EUGnrPmF6bfUoQ8NxyFIe7UradeXAJXHDBF4YAOsDDgArZNs/cTxta4ZIsVxlLe3v8DeV9XX3S4z/m1wu84IFZK58LyDrx1o0eQqs7iRmUs5n1MH7P5cA/oA== Received: from CYXPR12MB9320.namprd12.prod.outlook.com (2603:10b6:930:e6::9) by MN0PR12MB5764.namprd12.prod.outlook.com (2603:10b6:208:377::8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7849.17; Sat, 10 Aug 2024 21:05:37 +0000 Received: from CYXPR12MB9320.namprd12.prod.outlook.com ([fe80::9347:9720:e1df:bb5f]) by CYXPR12MB9320.namprd12.prod.outlook.com ([fe80::9347:9720:e1df:bb5f%3]) with mapi id 15.20.7849.018; Sat, 10 Aug 2024 21:05:37 +0000 From: Zi Yan To: David Hildenbrand Cc: Dev Jain , akpm@linux-foundation.org, shuah@kernel.org, willy@infradead.org, ryan.roberts@arm.com, anshuman.khandual@arm.com, catalin.marinas@arm.com, cl@gentwo.org, vbabka@suse.cz, mhocko@suse.com, apopple@nvidia.com, osalvador@suse.de, baolin.wang@linux.alibaba.com, dave.hansen@linux.intel.com, will@kernel.org, baohua@kernel.org, ioworker0@gmail.com, gshan@redhat.com, mark.rutland@arm.com, kirill.shutemov@linux.intel.com, hughd@google.com, aneesh.kumar@kernel.org, yang@os.amperecomputing.com, peterx@redhat.com, broonie@kernel.org, mgorman@techsingularity.net, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, Huang Ying Subject: Re: [PATCH 1/2] mm: Retry migration earlier upon refcount mismatch Date: Sat, 10 Aug 2024 17:05:33 -0400 X-Mailer: MailMate (1.14r6052) Message-ID: <148A7C69-F204-47EE-8F2E-E963E6D9CCCE@nvidia.com> In-Reply-To: <761ba58e-9d6f-4a14-a513-dcc098c2aa94@redhat.com> References: <20240809103129.365029-1-dev.jain@arm.com> <20240809103129.365029-2-dev.jain@arm.com> <761ba58e-9d6f-4a14-a513-dcc098c2aa94@redhat.com> Content-Type: multipart/signed; boundary="=_MailMate_2C05B843-5503-44FA-9F02-56D664616CA1_="; micalg=pgp-sha512; protocol="application/pgp-signature" X-ClientProxiedBy: BN0PR07CA0008.namprd07.prod.outlook.com (2603:10b6:408:141::35) To CYXPR12MB9320.namprd12.prod.outlook.com (2603:10b6:930:e6::9) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CYXPR12MB9320:EE_|MN0PR12MB5764:EE_ X-MS-Office365-Filtering-Correlation-Id: a3d46da2-ac72-4b90-f366-08dcb9802ef3 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|7416014|376014|366016; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?HwwnNBtriF+hCd21eXa3JYpWJW0th9XbgSaPrSQes4NdCxC+SlCVfa4p/vgc?= =?us-ascii?Q?kzTgDhUyyF4o2S/yQ87H9vXF0MbQPkb6pKkXJ8ScA0dVc83JsFGAg4Jfro9+?= =?us-ascii?Q?5kvbEL5dWuSiBdFary2cU9rwiWq3wIx6CbzY13D16ZytCSDvglMoWPmDnywi?= =?us-ascii?Q?FeY/ImGdXAu1m/ADtCx4xjM8AMY01jjltcOSaE5G8CXETRYOXB1dxi+9+tnS?= =?us-ascii?Q?WQl2NOxSGEma1+Dw5mxiUqdjYBWv7ayStqOb/83wh2ksyJ17u9kdGwjM44QE?= =?us-ascii?Q?p7rNyjVKEHkaIxK7F7bUqGktHVM5XzXEJu6cuJf265JQ0bnSUfgcKY3oqow8?= =?us-ascii?Q?fpRjI2jIn6cA7YoNBzAqlKVCkFNFG9K2iGfKo7SOrgwwjLiZ4g0OXhe2aCFx?= =?us-ascii?Q?XSHIUaIOXAGCeMijHtqUOScJBbJoGd/WDgbiyJ9W6r7ZSHA5RvueWRp1oLR9?= =?us-ascii?Q?kXmUeW7iLnVYVf5mRFVSX8mhEPP/fqlryN1QwkVXF0tIRrqC34ehqw7w3zY5?= =?us-ascii?Q?J4emikLHgAM38UG0Ee/84dVeEXXY7HbPGl9yR3aEAbyyXDRTxaTuaYe8Lupv?= =?us-ascii?Q?r/GXn+LTMn5pGoraTt8QNBIWqLKVTHwfZYpdZw8Ei2Rj7bmDucvADBY77yUL?= =?us-ascii?Q?/gduEm+IFWqUEEIYiOKd7Nho22B/ma6nvDwtk1fZpnKV+aJYIKdJTLtZlmD3?= =?us-ascii?Q?HHNBWwxk50A7+GeQXNevwDSRKLJwBAJyPh9nRcu3CEKh6ykvdzfya2suHncP?= =?us-ascii?Q?ui8kOqjfQRtJmipOC8nU3WpCleS5uhlrLrOhRw4dUwQJggYw2RQunWnPswti?= =?us-ascii?Q?z1A4Rw+jzcycEP2d4FbVqDhrlxc3FpSycTcs8DGkHl5BZXxVmCTKGezchTRy?= =?us-ascii?Q?0rJb2PIfCIwjHagCcIy1g1tqx7goCKkCTDK9gzUhopRcqixt1FL9kCpeWJP0?= =?us-ascii?Q?cl0I2+TyF+KDrj6MmnUine43+0Wzdz9FCCduhWtldLOYi1C3bgm9mfD/H+V9?= =?us-ascii?Q?jox2NXExZkKNO0x8bmwTMc9hJAwwl9/LqTrzV9MVPhzwYXu7brMCVU7HXFvG?= =?us-ascii?Q?oMgQ2GfwMPvRSIULG8iN8ad1xVbN0UrKyn/gTI4VvlxPijiJrDMBDj2D33Fk?= =?us-ascii?Q?P9n40a0qFjtMvB59P/ne8FIdOrKrkI6YEXamGryzmPsEzaQeLRjfXP04Oziv?= =?us-ascii?Q?c30AHvtw1aaMLmRbLx75U9j/ofvML5mOj+nAM3uTQU0E7u+o7nZ+IdrHqLoq?= =?us-ascii?Q?3YSwFLWTi3akCIXeP4g+riUX0VI12NlQp16Lxuia+N7IBDPKLDrkk1lJXtpG?= =?us-ascii?Q?PW2Q8tDBpzh1enJq327luSgYv4Cfk9I1RfU0In9pYlUPYg=3D=3D?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CYXPR12MB9320.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(7416014)(376014)(366016);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?ZqgPEQ/9sqJELZOJfcxXo98Q+pQOsZitY5dIVMsIdtvQyaeKJWepFfn2dwBy?= =?us-ascii?Q?6lfDNx58LFpF+Qw1rHc8dIYRfJHwRAvNHWXdQT7t7TSpkMAb6MSFzBcWiORk?= =?us-ascii?Q?2hg7hrcZE/qdzJ0ZSq6wCj9cOE5AJOHzUNEc2D09zP1RpASU5pX/ViLw5bZV?= =?us-ascii?Q?EP/mjPR86J8mhOgJsm5YqduR1zmzqB57OyVDi39ZwpbY4oRPkpBwX5XF1rGI?= =?us-ascii?Q?QVuw8aHBSyzaodV1N+NoX3SyccCBil52gWQJb+7HEKl/8Bp3s6eap9VuQuXb?= =?us-ascii?Q?eK/S15uWA56sdXQ4b+lVFD/N5pZ2ZlU5IFdABxe5JU6dJy5S5YJGClBWcPOf?= =?us-ascii?Q?MDSfQaNZk5ALBNZQ1JMz6vwYIWEelskBXKYCK5lvlOxFNPmQecfvYhdhE0Cb?= =?us-ascii?Q?2xJsJAl8Suzpy8TahNdgpacdZAT5l9umoD934Ilc8yrvEOOBBLNsbufwEoT1?= =?us-ascii?Q?l+zLM+zDrVzlslwqXi4qMFuSP3QqCM+2BsginEVO1CHP+g2eSxc6Vm0LjDfy?= =?us-ascii?Q?jkpDZC1DXuXKQgpAhwBvkEkAffD4nwUfYmfyKcJASXqcXlG8Dw2IXyyQVTcR?= =?us-ascii?Q?P4ImS5eZ48zZKf0B7132w2KWCDT2yKvd1CVegbxkepwYdCIHOrhH9SfdAX7V?= =?us-ascii?Q?a24pLXE9VNEaf5FVy9WAcJP2Kat4OqMeH9rhNvZSvhbLIsuElN+HmhT9royN?= =?us-ascii?Q?wcC379UbUkI8id2Hl9gtu/YAC1BUzhKzOrHNRUfz5CuP/vVhu9/JoUqxn5E7?= =?us-ascii?Q?MHFNPygikZ4eNZTjMjtdA95P3uuUOKBBcYuWt4Elpc3Y1ohpVeD4SvpMjQVJ?= =?us-ascii?Q?bWLi7+gcVrFOAaR6hiFImuqA3dOEY+1DMgVUGYsAYAHkfLQxVgMW7mX7tRxz?= =?us-ascii?Q?GibBFsRY/uBJO2fAqfs5CqnK8DbRlyrqK//+qWg3A80vy3sT0X231+DA/P0y?= =?us-ascii?Q?YuiGXB58wcOnMOXFPd9oER4cN8h3XfpoeyETrtTAu/hM8hN9oAngsuz4bdzc?= =?us-ascii?Q?LbYjnYEPKOLFxolKS1IFYpHx+25QO1+FgdGWGZMM4zYWqc5GxpGwdWS9xFEZ?= =?us-ascii?Q?k4Dbx4erlLa5DwpiEqrXpwz+ZCdj1A+UHNekTondtHKkR8DrSUZA35A0t4Y2?= =?us-ascii?Q?X+MRlYalZRrNRLpO7tE1a/51OtcSuinbRnYvX8+WeL2WhAWnJPND/TbBDbhM?= =?us-ascii?Q?uVonYTTWN8KGiJg3jZZcLBEFNSL/IKPEt0u5oW6bsN2XlGYaHQ5MYpOUrMlQ?= =?us-ascii?Q?M7duHoKU/mN8JYdjr10Zf8DmK3UH5QfJ+aIvm3+9ENeIlCUQ9mgzjulVSP4H?= =?us-ascii?Q?Ldd+uIamud1gV8jKaMlzt9JM4J5fg8RhKSxbImI3v1g9xKmPJpkKiujdQEDd?= =?us-ascii?Q?6OfP6iNy0FyMKatAFgs+fwnocxLwGjQaCWCtEDO+e2MU34v/Ik/lwzWUk87F?= =?us-ascii?Q?/93vFBbJhv2jryZ5b9Shcputx1ekIFWUMxEdu3kPhooVdtdvEJmgZf2TyI5M?= =?us-ascii?Q?y2P35dUIS4I//X8gZb8KBkDud6Z9ppzuy+a+Sd43yVFiB26KAxtgPkH0UFsG?= =?us-ascii?Q?oiKP/fWQ8KRqcfIsSUo=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: a3d46da2-ac72-4b90-f366-08dcb9802ef3 X-MS-Exchange-CrossTenant-AuthSource: CYXPR12MB9320.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Aug 2024 21:05:37.5797 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: tUMz1O3saR3szjP6Sps9YWQ47eND/1p2r1/9meIoEHP1gfrgd63V1DBVX7cMUxLk X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN0PR12MB5764 X-Rspam-User: X-Stat-Signature: 5hy85btog5h8x41qddehz87hxe6kjowa X-Rspamd-Queue-Id: D5B50140018 X-Rspamd-Server: rspam11 X-HE-Tag: 1723323941-911134 X-HE-Meta: U2FsdGVkX19job/1PYXDy3eZHUOLrBo8l8JqF9CfVfXJImmzF0/Ltb5U3kR78/HpPgqraM97SJh7vXppye0r1b3Lj02jSxPrC9UeYH5tB40op6Y4GSAoTCX4IABYdI2JHJbsaExpNEKTvq3x20M9iw5RV6x44XBywGLPl5xKtqfRR/ktXEyN6U49GXSpEn5cA7c4t39jhH/QlAQyLr0kfcws9+t6CC8jqXd79sBwFslNhYiwQ1TphP3l6zdLFbQnNd/vJo8+rcwxtouAyLO6mX7I0AhNePykcIFLdf67EE/79CtJEJSB/6/E6OwHank5c9wFqW9jKEnIhC3cHkQ5KwZMZoGv8gQY/A8yHkAumkyoeQgFeIoQzGLI+jmKT7IJoCnmJ8K2leR8d5kZvDU3FIHpOl9JQSQFk30Jte5ehTX3+sVcNh7uiJWEaW/WxIfWRtbtIXTrMyK7HY5hAx9RJpQsvNZaT1MU4t1oojhMZPRrXOohzoweZwH7IwJJuFWtRYqTkkeZYsspKR5H8HhWY84+Q3YZxNoRPTUTiUHKN9xycTSJxui0mz8exQJLmJpHkM+cQPLlcN6JlTSv49JOraz8QHWZifJBgLkI/v8yy3xH7Ws9GxkWPfZInEY2w2X7gMR63LOABiXf8z+01eF57dE005O/2zqlCgM4S4VxE5kN2iLAIgFG/yPE1xcgFAvcOgjSMTLFv3Fyt/izWM12U2ughpz8dNTM/ANkw7RtI8Lz4CwDh9a+27kBHLLXQhqhEL6cW9yKtVyPK6eR0ZKXip3knvcANj2qIoEFHK13D4u0PdFLM1udm+nX0i4CQ6xmh3ehxjxmYY+v0eo0EWiXrc2xQ33NhhrJJbFP01ctlZAWTk+fqKw0MEcHYfPFg/ipl2c/FyuZxrBSeiQrLVRxvAhOeT0ScNRBjzOWA3Cq78RrrBAblmt8PoZm8oAjkDbTZGW9jMnf5KCnUpMLHDr c/ahaFdZ gr82rxMQdLhXB0QFwtsYwmKqh2Iv7litGlKC5vSoDikQTIoJLxQinX+1J2XSmTd7hKYQr4B0mbLcOKvy5AFYiv3hopK9jUgxdJTYQid/GM1dBAH365oYI6zBbLnwAYMiPkE+vHLDCbj+bubcdX+J7hcsOP9Xd+LkH5f83ya6kt5vlDbIbueK2ChgPu/yZgbxDmb527nu5FTlCTRIwrOAZ6wiFFry1CajAAu5afbjDwZfeu969axWaDdTORZTgEKgMFSLryYJcG95vdkT3QAcTF2mDn40WTSUt+eE6mo4ci5iRrnRQD51R35USMWgxDwkDuZAiGaXb3dSGHT782Q9lUcHptuhHuq7ZyX/nb5J/qxUIh33B15H2D0Q46PDKOymuph1dK0tU3ziViNMX/58+SoOte7521c9W1rpWx54esn+uyZgecqL+Ji2XFA== 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: List-Subscribe: List-Unsubscribe: --=_MailMate_2C05B843-5503-44FA-9F02-56D664616CA1_= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On 9 Aug 2024, at 9:47, David Hildenbrand wrote: > On 09.08.24 12:31, Dev Jain wrote: >> As already being done in __migrate_folio(), wherein we backoff if the >> folio refcount is wrong, make this check during the unmapping phase, u= pon >> the failure of which, the original state of the PTEs will be restored = and >> the folio lock will be dropped via migrate_folio_undo_src(), any racin= g >> thread will make progress and migration will be retried. >> >> Signed-off-by: Dev Jain >> --- >> mm/migrate.c | 9 +++++++++ >> 1 file changed, 9 insertions(+) >> >> diff --git a/mm/migrate.c b/mm/migrate.c >> index e7296c0fb5d5..477acf996951 100644 >> --- a/mm/migrate.c >> +++ b/mm/migrate.c >> @@ -1250,6 +1250,15 @@ static int migrate_folio_unmap(new_folio_t get_= new_folio, >> } >> if (!folio_mapped(src)) { >> + /* >> + * Someone may have changed the refcount and maybe sleeping >> + * on the folio lock. In case of refcount mismatch, bail out, >> + * let the system make progress and retry. >> + */ >> + struct address_space *mapping =3D folio_mapping(src); >> + >> + if (folio_ref_count(src) !=3D folio_expected_refs(mapping, src)) >> + goto out; > > This really seems to be the latest point where we can "easily" back off= and unlock the source folio -- in this function :) > > I wonder if we should be smarter in the migrate_pages_batch() loop when= we start the actual migrations via migrate_folio_move(): if we detect th= at a folio has unexpected references *and* it has waiters (PG_waiters), b= ack off then and retry the folio later. If it only has unexpected referen= ces, just keep retrying: no waiters -> nobody is waiting for the lock to = make progress. > > For example, when migrate_folio_move() fails with -EAGAIN, check if the= re are waiters (PG_waiter?) and undo+unlock to try again later. > > But I'm not really a migration expert, so only my 2 cents :) Sounds reasonable to me. Also add Ying (the author of batch page migratio= n). -- Best Regards, Yan, Zi --=_MailMate_2C05B843-5503-44FA-9F02-56D664616CA1_= Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iQJDBAEBCgAtFiEE6rR4j8RuQ2XmaZol4n+egRQHKFQFAma31h4PHHppeUBudmlk aWEuY29tAAoJEOJ/noEUByhUUoMP/0eSbxgNB6BlaHRPwVre0ey0G7X9q2dpr8yN j4oiudiwcP14krla+kPnvzTGtxKMQO4gnBmBAqCSBLrvZXuX2t07U7U9WTlUmhwm KvgK3FewZ7pLV3Bj7AFAOEPDURSbc3DGR4fz96feAhKV2+QUxbTpuWUeIQe5uiVB gwsRdo8qpgB/xHqTQ+reU/wgwDqUwV9owgKUBiw25rX9JzPX15SVbwKpAC8UoqbN 6RCCBxRPww8ZwPymhoF/KLh5KWeSEG2txx64w0CZQF1Q5yFnVdFvh3KqUwU18aZQ xJ4+v9NxOh/QqPDL/2+6Mn3NwbRHqEc09mq6693/MCWqC0E3uvfTVobIDkIzvPhY bNSmn8V+YdA2PUh2GDQ/sdICbpZFP+17zxGvtVz+Ffa45LdYI3q6ROhcy3SXSqXp aIs6dvFFs9XCU+POz7ZskF8Gh9QCXBULPBNicFTVkTxnjA8xACyPRsDAieqF82VV vsalMTd6BvMznfDKya+4SI6QxWculNg0zusWKsBlNhmhze0HtrrTZDflWE1aIWxq d2r4/beYT/lmaDGBnqxOCnuf4LarQUk0hZ13td2DQJDLGcAB3q0sue1128ZNkeGE hamZUHQLNeUiDfIrc4Opj+YVxQXHgnGyAK0JECCvodDvgyAZunRui87pQa3Uz8sI WsT0NGgs =EbOb -----END PGP SIGNATURE----- --=_MailMate_2C05B843-5503-44FA-9F02-56D664616CA1_=--