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 X-Spam-Level: X-Spam-Status: No, score=-16.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,MSGID_FROM_MTA_HEADER, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E016EC433ED for ; Fri, 14 May 2021 13:50:30 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 634CA6145A for ; Fri, 14 May 2021 13:50:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 634CA6145A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=nvidia.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id ED50D6B0036; Fri, 14 May 2021 09:50:29 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E86716B006E; Fri, 14 May 2021 09:50:29 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CB1796B0070; Fri, 14 May 2021 09:50:29 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0188.hostedemail.com [216.40.44.188]) by kanga.kvack.org (Postfix) with ESMTP id 96CCC6B0036 for ; Fri, 14 May 2021 09:50:29 -0400 (EDT) Received: from smtpin38.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 29B1ABBFA for ; Fri, 14 May 2021 13:50:29 +0000 (UTC) X-FDA: 78139971378.38.82389A6 Received: from NAM12-MW2-obe.outbound.protection.outlook.com (mail-mw2nam12on2075.outbound.protection.outlook.com [40.107.244.75]) by imf11.hostedemail.com (Postfix) with ESMTP id F0C30200025A for ; Fri, 14 May 2021 13:50:26 +0000 (UTC) ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=ICXyzhgTT6+XTBwCIXpDuU2biFbmSZlO9s0u0J6M51O+vhDIRypUgmq5mJtzjd2HIx0gqovVeIqHC7g/FJjsjXgqKOyyIa1hLlgkQPEvFmedNmPtgE8tXUf7Xx+tym+uj8lpPpAde/7te+1vJP8skLW4PbDjWf99sdpyMVJDgnJe9s7X7YCmnJY01tqbexzy5jxuwfPCWFlOXhcn8PQynRuUCSP9l3Lbx5PNl0KFiMtOhVgS7uxLYn5bb4pak9Jsuo0ZjdYggFOod3qaaf0kpTjQfEOY/UclFqwyMdn4keA9PlGRC+dThojY5rpTn7o1y5PiampzK7J77/ZTtVlhcg== 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-SenderADCheck; bh=Ce/De1IECszkmsDMuudAD4Xdx++LZyZ7ox7MvfSO1gE=; b=CVbaA8+rVjDy50W/+EeQRX198LA7+yRVzAlDRAKKy4Eh5sRgWs2/or2VjVNyL3eK/8ry5p0Gvcf3aOfI7izicVvLnuL8guwlLOkJBz/j9c6+vquCpdEUKTj4gjzCLc7oNWsEaRkRI83WPmCKqjpJPO5/kLtPgl8Px/Z+tX/3zCswtIPDnN+K4tf6Eq57xqF0mMfIjEFN69U3f/msoF67XuFV3MNu5S3C40G+R7XSISPmJ/X2xziF9hhDGwn29vyq8PAYGOccQGjKC0Szpti1c25LStz8cyKX12caEvNELUoXZcfAD8al8ypno+DvhoYWAOT4pozZHBt+FYYaMA7seg== 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=Ce/De1IECszkmsDMuudAD4Xdx++LZyZ7ox7MvfSO1gE=; b=LWv6fQBgUK8mPkykSazxBliT0RtJanFt+uOvbcXSZT9xp9LpT2rX6B7le98C+HjNpUTNjEtD5zG/ePVKWM6jRcoyv921VT4eg2jZd7wsfEq/8BffIl44z2AbCkTnzz8wU+NZyUBvgl3+1gTe7Aim46iiecSEtcBQIOF5gNHFXIdK31XUHWQ0IM8jjG5/3QfyfCG+C66T12FzJNmu4KpNPHRC5sMhb+rUV+N2ztK/oMJ9AAeH8R98w7mJ0dKkL6Dg+kDlwKiZKo/kbSCvDEkQBOr4ceIVWW0+1phbRLlqQEmwlkq40Ql4ox/j3AgbDZPgf3nS1zSoszV8nRbXXHJmRA== Received: from MN2PR12MB3823.namprd12.prod.outlook.com (2603:10b6:208:168::26) by BL0PR12MB4849.namprd12.prod.outlook.com (2603:10b6:208:1c2::17) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4129.26; Fri, 14 May 2021 13:50:25 +0000 Received: from MN2PR12MB3823.namprd12.prod.outlook.com ([fe80::ccd7:fb49:6f2d:acf2]) by MN2PR12MB3823.namprd12.prod.outlook.com ([fe80::ccd7:fb49:6f2d:acf2%7]) with mapi id 15.20.4129.026; Fri, 14 May 2021 13:50:25 +0000 From: Zi Yan To: Yang Shi Cc: kirill.shutemov@linux.intel.com, wangyugui@e16-tech.com, hughd@google.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [v2 PATCH] mm: thp: check total_mapcount instead of page_mapcount Date: Fri, 14 May 2021 09:50:20 -0400 X-Mailer: MailMate (1.14r5804) Message-ID: <1E27805A-EC1E-4FCF-8C68-DA66FAE14E07@nvidia.com> In-Reply-To: <20210513212334.217424-1-shy828301@gmail.com> References: <20210513212334.217424-1-shy828301@gmail.com> Content-Type: multipart/signed; boundary="=_MailMate_5E37C9FB-9F95-4CDC-8939-07A1410F32EC_="; micalg=pgp-sha512; protocol="application/pgp-signature" X-Originating-IP: [216.228.112.21] X-ClientProxiedBy: BL1PR13CA0206.namprd13.prod.outlook.com (2603:10b6:208:2be::31) To MN2PR12MB3823.namprd12.prod.outlook.com (2603:10b6:208:168::26) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [10.2.60.96] (216.228.112.21) by BL1PR13CA0206.namprd13.prod.outlook.com (2603:10b6:208:2be::31) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4150.11 via Frontend Transport; Fri, 14 May 2021 13:50:23 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: b57ca9ce-aa0a-4853-68a4-08d916df39f0 X-MS-TrafficTypeDiagnostic: BL0PR12MB4849: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:9508; X-MS-Exchange-SenderADCheck: 1 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:MN2PR12MB3823.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(4636009)(376002)(346002)(366004)(39850400004)(136003)(396003)(6486002)(4326008)(186003)(5660300002)(16526019)(86362001)(235185007)(8676002)(2906002)(8936002)(26005)(956004)(478600001)(33964004)(83380400001)(316002)(38100700002)(21480400003)(16576012)(966005)(33656002)(66946007)(36756003)(66556008)(66476007)(2616005)(6916009)(53546011)(45980500001)(72826003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData: =?utf-8?B?NnNkelhkMlYvOU5CbEEraWlGR0hYRE1BNjNqeFhYQ0pGSFlIamRMVE05V29U?= =?utf-8?B?OERSMW4wUk44dVdFdjVJeC9vQnNjUWZURVBLM2d4eHlubzJZSUZEcnljTGRo?= =?utf-8?B?ZGtZbHBZcnVnNk03NnJxTnlsMFFoUXh3bWtXNzlsMjk5RWJSd0tmZjd5UzVE?= =?utf-8?B?TURBUldnRUxhblRjb1FLZUhRMzhOTVVscDRDMk9KYnFVY01BVCthZDRWdUlt?= =?utf-8?B?Y0dOK2N1OGx4Nzlib3UvdC90eHYzOGhrR21hL2svajZFNlBPRGhHTlppQnNh?= =?utf-8?B?eko2eDlTd3ZoZmE3ZWJlUEdIYnFHelRuNDJJTGx2bExUV2szZ0l2TFVBNTNK?= =?utf-8?B?SXZ1RlNTQmNGSHlvYXpONGFPWVJ4bTJocGhzMWdRZGJIR1dTYURiTnNBZlhX?= =?utf-8?B?NFdRYWJCWktuazhWQ05WTHc1NWJlQ2ZWZ0RqWFYweDFaMGRnSGRDdFJPYjh4?= =?utf-8?B?SUo3cm9ZWDlmVUNKbkhVUnhveHNlVU5HMUpMeUwyTDV5NU56bWFQTkpwVFBB?= =?utf-8?B?K2ttTm1vaVQrZnBVTDZCaTFRUTJhbzRkdlZUa25qYTJyYlNGaFQvM08vMklw?= =?utf-8?B?SFJORUVnR2pna1J0QWxUR3FsWVBESWdCdFJ3YUx2SEJKa08wakt0YWNUVFAy?= =?utf-8?B?RGxZc2hXN1N0dWh2ZmlFdjBmRGs0eWRNWS92QWFkYUJnZUdzV0RlYWFSVkw2?= =?utf-8?B?UkxtdWxacEZUWmdSZkg2TnVZbjNyN3krYXpzMm9NQWJHNGJKWlJudGg5dmxv?= =?utf-8?B?bVBJZ1JQei9rdHZOWk1LbnBPTnRSSldlVHJXMEdvbytUSFk4YmJ0K0pOZGdK?= =?utf-8?B?WHN1bnk5NytDRDh1dXdVRi9Qc3ZMRXgrc2pvT1VZS3Fwa25jWlNqcHV5eXN6?= =?utf-8?B?dW12dUNOYXVwelZmS0Q0SlNCSWd6UVlCTnF0Y1pJV3lETk9RZUJpaXpOajJC?= =?utf-8?B?SGpxOUQ5V0dzSGtXNjExWWZKd1lOUmRYZ2d1c2hrSnVidi9vdy9Hbm9YY0lG?= =?utf-8?B?TWRlUTRucFdwbFFDN3ltWnJkckljcmRBUFZCemN5V2xhV1hobkozaVMvUFcw?= =?utf-8?B?WGlmaUtRdWlxUGdiUVBKWTlJM2RFV2x3S3R2RUNFTW93R3hsMzRLQ3NQWUwr?= =?utf-8?B?YnVVdEQwN3EyRHpGL3hNSlA1Rm0xMnNIZGJTdDRZTkFxLzNjZXllajVJaWZn?= =?utf-8?B?V2hZdUVXc3VFQlRxUEdrL3RLckd3Q3dkL01XcUpmejVVelhzMGxDa2FwbTh3?= =?utf-8?B?SnVGei9qYjliL3d0anJISURaM1hCZVVFVHF2TElWejJhMjU3dmJLWlJRMjZK?= =?utf-8?B?ZjloWmZlUlJXNXpGUjd6K3hHbGFVQjg5clg1WjM5bTcxTUZZOTZvU0RkS3hw?= =?utf-8?B?QURSbmU4UHUzcjV4L0dnaUhnMnNOTVQxSVkrZUV0aWlGdEcvVWdjdU9zNTZS?= =?utf-8?B?UmFmRlNNemVQNVdTU0NOQlc0Rk1tRFVtWVNDanVwYlluZUE2TVNHeXorRGJS?= =?utf-8?B?Y2cxQmluQnBmNXFWVHF3cnF4WGIydlVRY09MYXdJQ29nNndyVC83ckNMcXlh?= =?utf-8?B?N1NtenRQcTdLN0pJVS9TQmtiZTVPMXdKNDdaaVpwbVJsY28yaXJoaG8xd0ZX?= =?utf-8?B?cUJGN3Zoa21PcldCTXVTWFR3NzJISEFlTW92RzBSMER4Tk9JbVNoS2RuSEZh?= =?utf-8?B?TVN3YkdDTlE2d3VZSXN1Z1cwNDlTdGxKM2tuemF5RTZFV1NXdlkxU1VLazJ6?= =?utf-8?Q?pKgXrf9sdxCcX780rrS1AEgL4ifFsRiWZR5Qwof?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: b57ca9ce-aa0a-4853-68a4-08d916df39f0 X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB3823.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 May 2021 13:50:25.6489 (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: iglcdDbSzF/PF8cXdNyOXHNwi7qHkmrYauG2zEMD9Xj7f4XwY4VIVQwLHCUr/I5h X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL0PR12MB4849 Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=LWv6fQBg; spf=none (imf11.hostedemail.com: domain of ziy@nvidia.com has no SPF policy when checking 40.107.244.75) smtp.mailfrom=ziy@nvidia.com; dmarc=pass (policy=none) header.from=nvidia.com X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: F0C30200025A X-Stat-Signature: ub14sj9xxxjp9ktae3n9rke5fmfjt69h X-HE-Tag: 1621000226-510484 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: --=_MailMate_5E37C9FB-9F95-4CDC-8939-07A1410F32EC_= Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 13 May 2021, at 17:23, Yang Shi wrote: > When debugging the bug reported by Wang Yugui [1], try_to_unmap() may > return false positive for PTE-mapped THP since page_mapcount() is used > to check if the THP is unmapped, but it just checks compound mapount an= d > head page's mapcount. If the THP is PTE-mapped and head page is not > mapped, it may return false positive. > > Use total_mapcount() instead of page_mapcount() for try_to_unmap() and > do so for the VM_BUG_ON_PAGE in split_huge_page_to_list as well. > > This changed the semantic of try_to_unmap(), but I don't see there is > any usecase that expects try_to_unmap() just unmap one subpage of a hug= e > page. So using page_mapcount() seems like a bug. > > [1] https://lore.kernel.org/linux-mm/20210412180659.B9E3.409509F4@e16-t= ech.com/ > > Signed-off-by: Yang Shi > --- > v2: Removed dead code and updated the comment of try_to_unmap() per Zi > Yan. > > mm/huge_memory.c | 11 +---------- > mm/rmap.c | 10 ++++++---- > 2 files changed, 7 insertions(+), 14 deletions(-) LGTM. Thanks. Reviewed-by: Zi Yan =E2=80=94 Best Regards, Yan Zi --=_MailMate_5E37C9FB-9F95-4CDC-8939-07A1410F32EC_= Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQJDBAEBCgAtFiEEh7yFAW3gwjwQ4C9anbJR82th+ooFAmCegBwPHHppeUBudmlk aWEuY29tAAoJEJ2yUfNrYfqKA80P/0KdZXSaJF8uO0L76EcWaym9B0ra8KvRdLE0 6vKvgL/yF1gM6ji0M51WuRv9C3SDc6G40UeHh0Yr6QVymw3Ig3Rh3arotHdWKNlW tS3sJfTy/zWH6peE8+8+sRCWbRs97WBq27TwRi3ythGQLsLq0l6NwV4pRUVe9Twu L77A0g92MbW6mUUjlfOy7mvZ6Nu1lFAEbiloObN6ObX249wwOfkGDDLmGA4aUZNk 3oArQklZjWMZpGzkuhLbfBv5p34VvBRvT/uRxrwM+f6huFwrtDoYbS2ER5ey3Zk+ mXddNXjBat/NB9fg9OHe8Z1ai8dI10qoIgXOQdotHmmFONcCdRlLwFEofkf53kFT lH6itY+QyiMM6tvQ+D4HDuvNdhqAY9R5zwn6/aCQZoNrmtHcrlroH8GcqQjkLwtF 01Dy7SJ1zH2ZLl3RmlA1hlup/07+KkGRN6+MwMuczGM8qeNrtqyXxHufp81nvNR3 /NN7sfqFrlUuG/CSMyaJuwhLL2fFV6GBlWH0UYYtfkgibw/knzDQjJ4q861Z4NKW 9i/WJowjSxpDh/cXixpS0AgQfbQ21445nacGnimM+fibE7Aku38CEcrHdIY9lBmh S4s0+ur5wEJ5Qcd2LrHQPmqhexgY6h1pgb+1z/4W5bLO6MVNjdwbtxvH4z/377TT GwpikBDB =qY49 -----END PGP SIGNATURE----- --=_MailMate_5E37C9FB-9F95-4CDC-8939-07A1410F32EC_=--