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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 83567C433EF for ; Mon, 18 Oct 2021 23:30:50 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0EA306108E for ; Mon, 18 Oct 2021 23:30:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 0EA306108E Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=nvidia.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 623D0900003; Mon, 18 Oct 2021 19:30:49 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5D344900002; Mon, 18 Oct 2021 19:30:49 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 44DA8900003; Mon, 18 Oct 2021 19:30:49 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0169.hostedemail.com [216.40.44.169]) by kanga.kvack.org (Postfix) with ESMTP id 3400F900002 for ; Mon, 18 Oct 2021 19:30:49 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id C5319181982DA for ; Mon, 18 Oct 2021 23:30:48 +0000 (UTC) X-FDA: 78711155376.02.D636FD3 Received: from NAM10-BN7-obe.outbound.protection.outlook.com (mail-bn7nam10on2084.outbound.protection.outlook.com [40.107.92.84]) by imf11.hostedemail.com (Postfix) with ESMTP id 5A65AF0000AA for ; Mon, 18 Oct 2021 23:30:48 +0000 (UTC) ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=CO7CSp/fTuyZlbbezq4rW9Fi3lg/ybjxgeCc5kG6uCw3FKkSs18pLr/WrxritTgFab+lIKW9jxxzpBRjGWEB8rY+7KONHiXhgWNLc4/LXld7Boj7vPIxFkxMW7u+9QKJJrxSkY6gjEqpd0f6HQ+PLuw0Q0NLK15qFgzNz9kW5fVvyvqA4TVznPWcWNfYkk8nLNRhRgr8pXSNZfnaHabxpZ4DjwZ5TEeqZKw7TNlnQBFi5LdldWUcojSWXDeKlTx1WPk80gUE/aLfMbx1rZYWo8szT0NRUHgcgCf0dg2R7p9LddugqC5WdVvqL3o5PDLJye+eZBfhhRtlYBQg5YnTCA== 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=aUeJMA7+NtJWfXyuNc9nd+CpLWMbLIaR47v8fGrtKFg=; b=fSglTj4i3uHGtKzg3iHuaM3RFlE4Wn4O1mEbGV49+Sc637lDU9A+XmAljnduaOPDCGzn5gN9dB3uM5ITp2nnbdx7bEgoD10f0RyvW+U5+ujJL9keXuvjNBytAkBrmVo1ktzpArOp7ZhtClwR9fCcrVHQjZvipFmnuGqejsq5l6n/dSwapzz+dVkeSmAX7yylTkGxlb1f7EFwJmctcid4h/Xb3414oY2lPLuXRUrq0hIDxUjXH0BW6LtuDooTVcVGthD1BAdrvhEAYdIpYb9zXMV6fLV+gG2a7ZQY7fWX7FmM+3sU2JvUfQWtHH8Vhk+1YiRSSNBuWhkdizXOZiV3Zw== 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=aUeJMA7+NtJWfXyuNc9nd+CpLWMbLIaR47v8fGrtKFg=; b=ISsScjIA/KwhchlDgYNA7OM2DlfjYhBfVPzNjOSxCUHOd/fsH86Nn4JG3tFQ+NLUWr86ewPXp4fKRO8x7ru+2yP7Q4cNi6XA9enPA0NwBxqWlx/mm+HGb0JXqwgoGycuy/C2MFIU5L/Q4O40Ue16U2znL6WjU9o/2mk+NHRw6hesE8/NEIYWQf8VLNwaqTRxenhMnVcluaMr+t4/rzPckBtzI/PY3If5DXUFtZR4ZeBDDgrmF96AKc2Y3gno53ICKveHXNlafiNhX3eTpmlLu3Nje7bJLgYXAJHjPtudTp5buE7Kdl4OAylIf/dr+/f6seOE2/phT9Ius+/TyrfHHQ== Received: from BL0PR12MB5506.namprd12.prod.outlook.com (2603:10b6:208:1cb::22) by BL1PR12MB5190.namprd12.prod.outlook.com (2603:10b6:208:31c::23) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4608.17; Mon, 18 Oct 2021 23:30:46 +0000 Received: from BL0PR12MB5506.namprd12.prod.outlook.com ([fe80::e8af:232:915e:2f95]) by BL0PR12MB5506.namprd12.prod.outlook.com ([fe80::e8af:232:915e:2f95%6]) with mapi id 15.20.4608.018; Mon, 18 Oct 2021 23:30:46 +0000 Date: Mon, 18 Oct 2021 20:30:45 -0300 From: Jason Gunthorpe To: Joao Martins Cc: Dan Williams , Gerald Schaefer , Christoph Hellwig , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Linux NVDIMM , linux-s390 , Matthew Wilcox , Alex Sierra , "Kuehling, Felix" , Linux MM , Ralph Campbell , Alistair Popple , Vishal Verma , Dave Jiang Subject: Re: can we finally kill off CONFIG_FS_DAX_LIMITED Message-ID: <20211018233045.GQ2744544@nvidia.com> References: <20210820054340.GA28560@lst.de> <20210823160546.0bf243bf@thinkpad> <20210823214708.77979b3f@thinkpad> <20210824202449.19d524b5@thinkpad> <20211014230439.GA3592864@nvidia.com> <5ca908e3-b4ad-dfef-d75f-75073d4165f7@oracle.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5ca908e3-b4ad-dfef-d75f-75073d4165f7@oracle.com> X-ClientProxiedBy: BL1PR13CA0016.namprd13.prod.outlook.com (2603:10b6:208:256::21) To BL0PR12MB5506.namprd12.prod.outlook.com (2603:10b6:208:1cb::22) MIME-Version: 1.0 Received: from mlx.ziepe.ca (142.162.113.129) by BL1PR13CA0016.namprd13.prod.outlook.com (2603:10b6:208:256::21) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4628.10 via Frontend Transport; Mon, 18 Oct 2021 23:30:46 +0000 Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1mcc5d-00GXW8-J2; Mon, 18 Oct 2021 20:30:45 -0300 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 0b433061-d2e2-4c98-07fd-08d9928f4fa3 X-MS-TrafficTypeDiagnostic: BL1PR12MB5190: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:7219; 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:BL0PR12MB5506.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(4636009)(366004)(66556008)(66946007)(66476007)(2616005)(426003)(83380400001)(7416002)(316002)(6916009)(8936002)(1076003)(86362001)(26005)(33656002)(508600001)(38100700002)(36756003)(186003)(54906003)(9786002)(9746002)(2906002)(4326008)(5660300002)(8676002);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?kwtHPgORhYc9wlcoJZcUQBMgQOVVmOfjMMJ+ly/Ik1XErDruHKvoQzu+yq9Z?= =?us-ascii?Q?+X7byI1zeLYGwkWQBJ/ifVs+kQdjBB0t5JcgjcF7aUSWRaJfPcimUpSxfpTo?= =?us-ascii?Q?w+N+59XyGgqXm2ndc4tDX9+xQxBrg2JOVh3t8NLSEDKw0VcXqZwP2ASCkjoz?= =?us-ascii?Q?HNjvit1zptvL2aE+kAp4xyyELlo+nQI3LbS0tEIVSqdjhEqa4P+C3ScjqyhL?= =?us-ascii?Q?Q9B/D0zfoAlD9qntMELiGdbJ2QsqgMQvqFhLsKvi+nyph5X2FlISjrS3NCfv?= =?us-ascii?Q?nWXWuotF8Z07L80vnELWy3sB6hYtxW9qf3+/11UJMoyG0C3QA9eDcpiVONAD?= =?us-ascii?Q?pFxgHUlWeSIKswywkmQfMs/PTTlvkXAlCaqjdgUtAR3XGkyqXvb5s9fWvkKI?= =?us-ascii?Q?CWvTkddU76LbZzqkzwYkXItgN8cdwN57XV2sgeLaB72FGI8aHXAwqcu74bs8?= =?us-ascii?Q?hUamAL8I+29XPlnX51WzI6eIPpJuXKuIqB8pdMlafqHp/MEA8Yzcb59DK8CJ?= =?us-ascii?Q?sORTl5dYiyXTAOff/Z2syVoWyHqAMFXpxEMT5S+YrpJrOPiSqTj1bAU+xn1t?= =?us-ascii?Q?7KMz+24JAZPY62jT1pP//3Lj/EOU8R7z+k1rKD28b9LDDj1sAJisOf7IlrOK?= =?us-ascii?Q?szK+zpksNnDdcmykjmpN76muqnAjXrsGp6kQinJ0+t/S6ynRO/cegnO/NIrI?= =?us-ascii?Q?SedpvGIRBKJwY6DhwalpthAy7JFYomBtfnMShUZ8dsM3RrS6hlt6o8mUpb3g?= =?us-ascii?Q?kXoqc8dAlMZlT3WxDOtTLDBoF2P1zbbKoF7aj52xyRmCxHp6YXbd8dVl5snl?= =?us-ascii?Q?o2yFrDLXV3jZoyzcCJ2Yna1u7z7R4wSGVb9BevAK8upZOli2JWYTjqBna16H?= =?us-ascii?Q?RIaHKokgSNfPIc6xRWFc7iGhqBER4zCSf8IvXZaJXpMw2JqDWn+kfzUG3cvO?= =?us-ascii?Q?FZBXSRGU8Vite1WVeTh08S01263KJRS+Z2PI79WZUTpBSgUGgRmbfjykROMN?= =?us-ascii?Q?os9S4S0dT7jeCTEP6xh4y3OW5+Ktx9Cq21SJifu2aJSSi7VAe9V/joSo3mYI?= =?us-ascii?Q?wIm2F4NVMF1RchxgNKzfWq5s8wWagLpjAwrHz6aGmZlbqsTLNhPxwov5zyvl?= =?us-ascii?Q?0jftMG4wb6E6/Ish0CFF1l8eIdvsjU4TqyWuZmgEE6Mi8Jt0iX1OWK1GwVlX?= =?us-ascii?Q?m5xwCiNNa08FHtc7Y75RGOQVI1Lgy0TPHsyWuzzg8ky+PDdma9K/IwRBIpY3?= =?us-ascii?Q?Fz4oSSKMhXbvbobzVSGhVSOMnbq9fRxkflHTlme/zFwHAXfnn2hkB003uFYO?= =?us-ascii?Q?JAE0i6/eJBI5Lnz1UpuxMDx5?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 0b433061-d2e2-4c98-07fd-08d9928f4fa3 X-MS-Exchange-CrossTenant-AuthSource: BL0PR12MB5506.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Oct 2021 23:30:46.6088 (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: TML/lclX5CiMsFvx0gsz2TdoIBHamkci/FxJOsdQiTQYUhLRZsFUHFgfdUuX3HWU X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL1PR12MB5190 Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=ISsScjIA; dmarc=pass (policy=quarantine) header.from=nvidia.com; spf=none (imf11.hostedemail.com: domain of jgg@nvidia.com has no SPF policy when checking 40.107.92.84) smtp.mailfrom=jgg@nvidia.com X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 5A65AF0000AA X-Stat-Signature: qjcxp9c89nr7knokj185urhkzzuzjs14 X-HE-Tag: 1634599848-587449 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000002, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Oct 15, 2021 at 01:22:41AM +0100, Joao Martins wrote: > dev_pagemap_mapping_shift() does a lookup to figure out > which order is the page table entry represents. is_zone_device_page() > is already used to gate usage of dev_pagemap_mapping_shift(). I think > this might be an artifact of the same issue as 3) in which PMDs/PUDs > are represented with base pages and hence you can't do what the rest > of the world does with: This code is looks broken as written. vma_address() relies on certain properties that I maybe DAX (maybe even only FSDAX?) sets on its ZONE_DEVICE pages, and dev_pagemap_mapping_shift() does not handle the -EFAULT return. It will crash if a memory failure hits any other kind of ZONE_DEVICE area. I'm not sure the comment is correct anyhow: /* * Unmap the largest mapping to avoid breaking up * device-dax mappings which are constant size. The * actual size of the mapping being torn down is * communicated in siginfo, see kill_proc() */ unmap_mapping_range(page->mapping, start, size, 0); Beacuse for non PageAnon unmap_mapping_range() does either zap_huge_pud(), __split_huge_pmd(), or zap_huge_pmd(). Despite it's name __split_huge_pmd() does not actually split, it will call __split_huge_pmd_locked: } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd))) goto out; __split_huge_pmd_locked(vma, pmd, range.start, freeze); Which does if (!vma_is_anonymous(vma)) { old_pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); Which is a zap, not split. So I wonder if there is a reason to use anything other than 4k here for DAX? > tk->size_shift = page_shift(compound_head(p)); > > ... as page_shift() would just return PAGE_SHIFT (as compound_order() is 0). And what would be so wrong with memory failure doing this as a 4k page? Jason