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 457CBC54E58 for ; Fri, 22 Mar 2024 00:16:56 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 89D826B0087; Thu, 21 Mar 2024 20:16:55 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 825AE6B0088; Thu, 21 Mar 2024 20:16:55 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 69F056B008A; Thu, 21 Mar 2024 20:16:55 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 57BB46B0087 for ; Thu, 21 Mar 2024 20:16:55 -0400 (EDT) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 1B9AEA1105 for ; Fri, 22 Mar 2024 00:16:55 +0000 (UTC) X-FDA: 81922759590.12.51699BC Received: from NAM11-DM6-obe.outbound.protection.outlook.com (mail-dm6nam11on2046.outbound.protection.outlook.com [40.107.223.46]) by imf30.hostedemail.com (Postfix) with ESMTP id 5B26080015 for ; Fri, 22 Mar 2024 00:16:52 +0000 (UTC) Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=YlL0RuO8; spf=pass (imf30.hostedemail.com: domain of apopple@nvidia.com designates 40.107.223.46 as permitted sender) smtp.mailfrom=apopple@nvidia.com; arc=pass ("microsoft.com:s=arcselector9901:i=1"); dmarc=pass (policy=reject) header.from=nvidia.com ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1711066612; a=rsa-sha256; cv=pass; b=iojZpT+YczmRS0zRg9F1GwRL/WVgBBVMfIDDVVp+YhWlz4ZovMm7IJVsi6L5bNcfI6ZhYW 1q8qd35aiwjiRuMiS18qnavn57RXPqtwLZyEDcnE6IwwY1ltXe4EEMsbNAqTeSktBiNRP9 uGXJ1znpBC5w5UOIEM4AF2ts3CLsNAo= ARC-Authentication-Results: i=2; imf30.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=YlL0RuO8; spf=pass (imf30.hostedemail.com: domain of apopple@nvidia.com designates 40.107.223.46 as permitted sender) smtp.mailfrom=apopple@nvidia.com; arc=pass ("microsoft.com:s=arcselector9901: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=1711066612; 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=peSGCTNN4d0KB/c9m5SUtHQjzyZArizj4p6xYWRHa0Q=; b=Nrv1wCUyWBFbqJ5hsfyQeo5VOaS4NJ7OWh2t5fdUzMVXKmrtttck8p/RYU1WcS8ZeKq83x uboB3redt8G8G5ce3MmssNP/fTwAop2oN8DKKOnokcu8WLuKValREeQ5iJf4h2SeBCVknN EJJxx5AyHXrIyQH7mKs+EPSugg0qK3I= ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=Sy0hoW8jW8Hew4KC+XpwsBswIFP5kNB9kPuI0OVK6eqZ1XsMwLsIz989fwOz57WiW+pYB37cZ8/CbgTIudkn1iaeJnM/Qpd1xX/Ocv5Jm79zHDMbtgLkHC3sAa8tqgqwdxmMvFYOeyq0nD4fclHIL45Hrmh7k04+O0gP1EVRh9VRwVWntc2NlMPnnrGpPiAO17AKlGBxLN/ynXq4/XX/WJdLe8lsLMrnrmaoyvVjyVaCrMeBFjm/baIG3asmJLlp/8ZoIqUDZp3r30XqL2dVtu1VJsWJUpkVRFXVQuK7L1x0ME6xKVtKvi8MoVPNsgHEGUWx4YmFaMgGm4V8in6Ahw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; 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=peSGCTNN4d0KB/c9m5SUtHQjzyZArizj4p6xYWRHa0Q=; b=LJ7cwYB/aMFdB1Rf7Pq2MesP81+bxXR3WRbslmR7acwYiNI+POXh7stLNgLckbaCSyYsE0wJ9rGkzcCGWxNuLl2AySdcQo2/ySC7Yj0vryn+Edv6R6cB9+Vw0BlcN/jlZXnUJBqVdPmLsTxv8l17Hv3H6bnaS6SEZ/xh5ZxEzlF5G1F80SvdHOPE2Ilqe5ys7QFi5SV6/m4t94Mu70qOES0rw7LvqTyzpvrOV+gIgJYc9A/YuySC74TZzWcfZV7Dca212mCznvSK6mKEaxMtUfSnktQ7gAJMB+mpPoSpFeU834sEpeGowPFgix+KxCXjShRmQaZ6UbP5KANIE47EtQ== 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=peSGCTNN4d0KB/c9m5SUtHQjzyZArizj4p6xYWRHa0Q=; b=YlL0RuO88VRiCDxGc5gMjZ1r09Lus1kgj9AI/WPVq6aK0aiidJ1vHJ0oYSNTHqPDPU/z7QijdM+1eKPWLii8drQPKz8x7zkKEsHqtzAnYqBlwaHUslkZUy83pVCBAyCRsdA7zEgRnYzanr/JfgJjP3rrA8PRE2X6dgz7wSugNwlu3XqRwAB6NUfNsTF3JNZG22VyVxvHyQA449yQijeZIuDyyti81hdoXhBNeYYT/hTiEb/SXsWkPiPkmTZvhi1qTCzWVYoE4d0LU0XC6cpx/BfuRcOjFGzjr3tdYPQnGuJxFK2hY3Szjyp3VUqt1xyqGZMC67sHv/tEhJiogu7oCQ== Received: from DS0PR12MB7726.namprd12.prod.outlook.com (2603:10b6:8:130::6) by SJ0PR12MB6709.namprd12.prod.outlook.com (2603:10b6:a03:44a::20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7386.28; Fri, 22 Mar 2024 00:16:47 +0000 Received: from DS0PR12MB7726.namprd12.prod.outlook.com ([fe80::c5de:1187:4532:de80]) by DS0PR12MB7726.namprd12.prod.outlook.com ([fe80::c5de:1187:4532:de80%7]) with mapi id 15.20.7386.025; Fri, 22 Mar 2024 00:16:46 +0000 References: <87ttlhmj9p.fsf@nvdebian.thelocal> <65f148866bc56_a9b42947@dwillia2-mobl3.amr.corp.intel.com.notmuch> <87y1ad776c.fsf@nvdebian.thelocal> <878r2c6t99.fsf@nvdebian.thelocal> <65fbcdaf2042f_aa222948c@dwillia2-mobl3.amr.corp.intel.com.notmuch> User-agent: mu4e 1.10.8; emacs 29.1 From: Alistair Popple To: Dan Williams Cc: linux-mm@kvack.org, jhubbard@nvidia.com, rcampbell@nvidia.com, willy@infradead.org, jgg@nvidia.com, david@fromorbit.com, linux-fsdevel@vger.kernel.org, jack@suse.cz, djwong@kernel.org, hch@lst.de, david@redhat.com, ruansy.fnst@fujitsu.com Subject: Re: ZONE_DEVICE refcounting Date: Fri, 22 Mar 2024 11:01:25 +1100 In-reply-to: <65fbcdaf2042f_aa222948c@dwillia2-mobl3.amr.corp.intel.com.notmuch> Message-ID: <874jcz6ryu.fsf@nvdebian.thelocal> Content-Type: text/plain X-ClientProxiedBy: SYYP282CA0004.AUSP282.PROD.OUTLOOK.COM (2603:10c6:10:b4::14) To DS0PR12MB7726.namprd12.prod.outlook.com (2603:10b6:8:130::6) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS0PR12MB7726:EE_|SJ0PR12MB6709:EE_ X-MS-Office365-Filtering-Correlation-Id: d8604ae2-d875-4444-4791-08dc4a055c38 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DS0PR12MB7726.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230031)(1800799015)(366007)(376005)(7416005);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?2u79CtH6XNZ3ZRsKbjX/ct8UgofZ1U/RI+CVfLB/XvtKtuq1P88dNbCHxuei?= =?us-ascii?Q?Z8ADyAioqBf5Nz7k74fxeKqv74ceWM2JzAfaVyuxSHXI7y8HkmP/8j1gMOUY?= =?us-ascii?Q?isJ6JJckoFY/37gUCbIUGs+cHThUF2KzGztCQ51mHcf2/CJ7dSUbRWpEPkLs?= =?us-ascii?Q?NKGmtb85hJZU84GGykLCR5cOT4mdHdLoihseWb5ExeX8B3AyU074qDa9Bu5h?= =?us-ascii?Q?t111VGjJlw9xSm1nbQsL+mKTG7n6xlh4H8h7gdKiI1imyFm1K4OLu6bWOKvC?= =?us-ascii?Q?YY3FG3pMtysZ2X6wfFaPS8BPScXsqjJgtCNXCld/z+WzWvdaBv6IKXSq17MM?= =?us-ascii?Q?LWW9msQ14TevXbs06nE/SEl7fIq+mjFfOK1VwcIBjc6bTMpTxqGkbVtPq560?= =?us-ascii?Q?a3y0UrqZBhyn/krnewuDa1ABWLUF8Xl7K57fk0r3wR2UTP6XpSipWZkNCBDN?= =?us-ascii?Q?llUzAw18gFOyVgL0xP5qWiGHPEEwzlP1PgQX8O/wzfTsVrRwh0Opvp8D5JkL?= =?us-ascii?Q?8fuwIUSLxdpLJKkTflmgEnhiu38RWgOFXdr7VneVgPtyBBfrp9ruXkxP7CVF?= =?us-ascii?Q?QjGj3NsVDORTJWs7+LrZIUZHTRIXtXPDMNea1Zn0hk3mM2a+/XSlDWTztlaW?= =?us-ascii?Q?ROC1NIKX23M8i8NENqiFnfrcOxs0cnM6j83Q8WXNwte6WX3ogw1h26z09t8K?= =?us-ascii?Q?EyI4jnEZ9MniBn67LhCb+W9yLPSYazdOtURh4yXPD0r5BOHF+BsxANI7dPpo?= =?us-ascii?Q?L2oEWub3MfbKs112dlXHUwvDtX+qbD5KInRcqarTsQyQMEeq6PQRj5YAAdrq?= =?us-ascii?Q?DK8L6Lm4WnyZfNa6oyzw/nN6rnSy/RMThLRpfJ0AplEjqnNCilplxzolwuF7?= =?us-ascii?Q?mngVdRquiXiniz9sME5zRY4MVvT8F8zrR/AZHMi0mJxRuy8e8NehOascg+jF?= =?us-ascii?Q?4J8QmXDFfrXE7dGXWm6ow1CWFHLH4KxqZZMi9MN95tTmgMaozkuBK+ay2Mwb?= =?us-ascii?Q?A+8GQD3Gq6y398i30u+dcNZSqMSYeZciabhsJ7csh301wnnGie1ho1Ill6id?= =?us-ascii?Q?jxV+KtUq45wTKJK+fMwz+6ZWmX1/Eif5yGmDIxJXzibRmAHlU56+960k9UID?= =?us-ascii?Q?JpKK4WLwU/qMXeAy6uvyz6oqHVyAeHOxOWtNDuF6ztzyuMvr98LyXcU4Cdmn?= =?us-ascii?Q?rIufVlNe3jy98LpnG+U7coPHUTQY/R6w1b3flqGFDHJPMKO7mhnYmMR4+3L9?= =?us-ascii?Q?kg89LpR4FQgPlGqoZ+SEUlN68XpsqKWAAlcAvQpjYqGHONEU3LbA5J64qU4Y?= =?us-ascii?Q?luLlSqSuvZKLEQGyRIFNZvmrDtGzJ/ZtjFbTPVpq4k0jg4B7o0xycmMItDRV?= =?us-ascii?Q?ezfAWjSoWA+Myzt0Ridfk7nvbAmaG2y9L6ojwjal0dyCACLdR439t9WUr5B1?= =?us-ascii?Q?NYtJ1vORlkmj89Y65F5DyneK///RaX75AbXbKTS4SiDbstPTP+Lw40S22TCs?= =?us-ascii?Q?Vc204uLcNw5xPexDRBmbWB27yLu7/g4OjwqCbumA2UUEJ9IR96XdpS0gvYeL?= =?us-ascii?Q?pbQuEQhptdROxygXwUGfW6F3YIfNRLgF7lORrPAc?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: d8604ae2-d875-4444-4791-08dc4a055c38 X-MS-Exchange-CrossTenant-AuthSource: DS0PR12MB7726.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Mar 2024 00:16:46.4078 (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: 8Nu0Q4o9sNDXPEgnLlfg0zlQURgBxEVs8ahkCjKJSfefjCvEzLkrXxuApowgMyxfhL+9jtnf5YQ9UqqxTo0f0g== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR12MB6709 X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 5B26080015 X-Stat-Signature: oroe6j5tt5ym9ieduk1p5wdb7ht1hj9h X-Rspam-User: X-HE-Tag: 1711066612-625049 X-HE-Meta: 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 W1bpHva4 9wdL1xIqmBpF/5Yv2kQEenY2FpX60zGDniV9je9ixCza5u50JlDaSJH7N0iE7lj06k2c0H5WY4TUBq2JfF1AN2bGYrl4ZB0gBlDZGqDKucWtVDbrhkMoIrmc+Msf2m5Yzq9408Vpol41fKk3Bfh8w+he45oxCBkYMrCeLdOfGJouU1eQVPHhkEAee9d8cfjLQRb2QMHV3jJ7rA6J6M1xfXEJCXzcOV1//4RdDUIuE9m6FqspiofI94CI0uQ== 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: Dan Williams writes: > Alistair Popple wrote: >> >> Alistair Popple writes: >> >> > Dan Williams writes: >> > >> >> Alistair Popple wrote: >> > >> > I also noticed folio_anon() is not safe to call on a FS DAX page due to >> > sharing PAGE_MAPPING_DAX_SHARED. >> >> Also it feels like I could be missing something here. AFAICT the >> page->mapping and page->index fields can't actually be used outside of >> fs/dax because they are overloaded for the shared case. Therefore >> setting/clearing them could be skipped and the only reason for doing so >> is so dax_associate_entry()/dax_disassociate_entry() can generate >> warnings which should never occur anyway. So all that code is >> functionally unnecessary. > > What do you mean outside of fs/dax, do you literally mean outside of > fs/dax.c, or the devdax case (i.e. dax without fs-entanglements)? Only the cases fs dax pages might need it. ie. Not devdax which I haven't looked at closely yet. > Memory > failure needs ->mapping and ->index to rmap dax pages. See > mm/memory-failure.c::__add_to_kill() and > mm/memory-failure.c::__add_to_kill_fsdax() where that latter one is for > cases where the fs needs has signed up to react to dax page failure. How does that work for reflink/shared pages which overwrite page->mapping and page->index? Eg. in __add_to_kill() if *p is a shared fs dax page then p->mapping == PAGE_MAPPING_DAX_SHARED and page_address_in_vma(vma, p) will probably crash. Thanks.