From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=pass header.oldest-pass=0 smtp.remote-ip=40.93.194.50 ARC-Seal: i=2; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=pass; t=1793054401; b=2zzKpoBqh02sYrzsa53Cmnf3iskhCHlMqza8FsR8V3a8iCWch66cav3RXsgoryn13VBe /z6KK96VrocK4ecEVzGZeECyTrO0/QvfQfGGUJuVdFSD3+l5utg+02eYUFlEpkP4j+sqC tLM/KmuRZN3b2AyjML08i4oCGdAlPCUc8mUwTFIkqAw/4D6nU7Msqh3nsi9lXLJxWze5B hd+tlGKnNMH3HzXJ973k9FHMuIPwbWMUcn/2hCI3GqTChotF7fkgVXDYCGVHJcaxFiy0S JiPyBxiElX7vXfP38dQMNbsyHpoWg20nh3Y0yXmAZMqNH5peVgK7+j3rolfWehNhZNQ== ARC-Message-Signature: i=2; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793054401; h=DMARC-Filter:DKIM-Signature:Received:Received:From:To:Cc:Subject: Date:X-Mailer:Message-ID:In-Reply-To:References:Content-Type: Content-Transfer-Encoding:X-MS-Reactions:X-ClientProxiedBy: MIME-Version:X-MS-PublicTrafficType:X-MS-TrafficTypeDiagnostic: X-MS-Office365-Filtering-Correlation-Id:X-MS-Exchange-SenderADCheck: X-MS-Exchange-AntiSpam-Relay:X-Microsoft-Antispam: X-Microsoft-Antispam-Message-Info:X-Forefront-Antispam-Report: X-MS-Exchange-AntiSpam-MessageData-ChunkCount: X-MS-Exchange-AntiSpam-MessageData-0:X-OriginatorOrg: X-MS-Exchange-CrossTenant-Network-Message-Id: X-MS-Exchange-CrossTenant-AuthSource:X-MS-Exchange-CrossTenant-AuthAs: X-MS-Exchange-CrossTenant-OriginalArrivalTime: X-MS-Exchange-CrossTenant-FromEntityHeader: X-MS-Exchange-CrossTenant-Id:X-MS-Exchange-CrossTenant-MailboxType: X-MS-Exchange-CrossTenant-UserPrincipalName: X-MS-Exchange-Transport-CrossTenantHeadersStamped; bh=66VWupt/mZ6FBgq5tKboKohYjAfYUEXR7z0xP2PP65E=; b=5Me+jDcMRuWGQ+IK+ubpCZNtUvpo461xcuH/qKTbe+MQXoHckyOZYjb8x4PPvdoy7+hw LUB2Gv0cDYv+p2+bwOfthZQ2EHhkBcPbEbju1E2cocX95DeJ31HWJG4SMrMP6rMYMwsaf t/lAyaS3pggtouzDOq26T/wvsXAaCbg/HFIeLnuyc0uVRioLXtvd5O0QTGts2bvavqZAj CSpGBNuSCrobls/D3WJAXt+u1MUCWeA/3xirXWXS4YW7tzWE3ULCmuWiLQ16HFAHHTONF CHVi7L+pxx6HidPgayw5KLE8++e2rSbsokhtBRHaAChyAlKnzoDnr87yBcX7y3Cz1mQ== ARC-Authentication-Results: i=2; smtp.subspace.kernel.org; dmarc=pass header.from=nvidia.com; spf=fail smtp.mailfrom=nvidia.com; dkim=pass header.d=Nvidia.com header.i=@Nvidia.com header.a=rsa-sha256 header.s=selector2 header.b=CyhS7K6h; arc=pass header.oldest-pass=0 smtp.remote-ip=40.93.194.50 Received: from SN4PR0501CU005.outbound.protection.outlook.com (mail-southcentralusazon11011050.outbound.protection.outlook.com [40.93.194.50]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (secp384r1) server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 91943606A31A; Mon, 26 Oct 2026 22:40:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 91943606A31A Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=nvidia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=Nvidia.com header.i=@Nvidia.com header.a=rsa-sha256 header.s=selector2 header.b=CyhS7K6h ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=iLDJqDPuaqbCrSy/TC5HI/qDExVZ0goG8SAMrKXY7EeuAAxVYFwXBt7y4EZ5DnrC8+w/NTWdwEiGsCgNSpFZPzHubjlIY5SWg9HrwA6qdA4Or5pe3Oy4SpLvZD95IyKKMrzQTcnEAGmOxuTGPUT9gpXOd5TZ5rDpztW6/FkvLeR8lp83nnrSq7ArvlX4g6wwpVw5Ec4gjIjgkHZWf3k+pTty72VjoRhrAv5lwhoVdIBe658CpRkap2aTSP0G4pNr9VHCqak+Amse9M08WKlKv3rH3QGb3nAqQ/XxBJzY2IdCJhmC7IKIlRe4Vz486RLBQKze99LzMUp58y9hYxb+Lw== 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=66VWupt/mZ6FBgq5tKboKohYjAfYUEXR7z0xP2PP65E=; b=C49wqJZuaoLUTKlV+QBZKr4JBBtG4a9MHgiN+7bUB7kV4KxBMUQnokxWXjcqvjH05jstnukmDGHobdF0UubqtQS9U6LExfmTjj/LmiC32wVwfqxl9RgJTX5tV9sFpwtV2xA/rjFhj/N38Sngsj4julZzK+h/F9qQKvZSMnzpx43smMoPUSk27T5f439zCdV4C2H7UItpe3CyHlEUaM84pVFGmbsWoA9z94Y02yNKMDhGr3RKnFxOTFalB0sjVYY10bmB7LU+CxYjTGmFrTtsnlk584AybV/J+FKoZBtGgCNoupawIYfInw/mN5CAYGOMNLshndvoUOYQMvVs3M9rUA== 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=66VWupt/mZ6FBgq5tKboKohYjAfYUEXR7z0xP2PP65E=; b=CyhS7K6hFjclWoOvANlwXmxAycb8CKazaIWrT65zNzcNNfrlmpcmFF/rCljDRv5kGxejrOxET8CzbtH9qqHUcJZKQj9xK+JgaCZ0CIsGcvc9eIuXffQM1MQorqOlFL0sHj53UHY2QaTv1NmzqpkaGgerI4O6gUPeVeL9ElVesdzNrFbxYRaTLyd6uvJVa5n3MvAIb5ayl4bEoBayuzhsWzTZcMvCcp5vnza+ozZYsZMS5+OjTsAI1J2Eoz21vCEu2+uIyoTQ1MuIwkf/DFQtfRMaszBQ1tWhaFr+ySppTqcwJh6I/q7BcmuwbXXdusOuw817VJepjjqbPpUEFMmfNQ== Authentication-Results: mx.microsoft.com 1; dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from IA0PR12MB8374.namprd12.prod.outlook.com (2603:10b6:208:40e::7) by LV2PR12MB863586.namprd12.prod.outlook.com (2603:10b6:404:300::21) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.546.22; Mon, 26 Oct 2026 22:39:57 +0000 Received: from IA0PR12MB8374.namprd12.prod.outlook.com ([fe80::d85f:4c87:ae84:3f16]) by IA0PR12MB8374.namprd12.prod.outlook.com ([fe80::d85f:4c87:ae84:3f16%6]) with mapi id 15.21.0546.021; Mon, 26 Oct 2026 22:39:57 +0000 From: Zi Yan To: "David Hildenbrand (Arm)" , Andrew Morton , Zhang Yi Cc: Gregory Price , Joshua Hahn , Rakie Kim , Ying Huang , Johannes Weiner , Vladimir Davydov , Michal Hocko , Hugh Dickins , Baolin Wang , Lukas Czerner , Carlos Maiolino , Christian Brauner , Jan Kara , Daniel Verkamp , Jeff Xu , Muchun Song , Oscar Salvador , David Stevens , "Matthew Wilcox (Oracle)" , William Kucharski , Chris Li , Kairui Song , Nhat Pham , Miaohe Lin , Naoya Horiguchi , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Chris Mason , stable@vger.kernel.org Subject: Re: [PATCH 07/16] mm/shmem: avoid moving the truncation start backwards Date: Mon, 26 Oct 2026 18:39:54 -0400 X-Mailer: MailMate (3.0r7032) Message-ID: In-Reply-To: <583728ed-dc63-4685-9ac5-5a980db55973@kernel.org> References: <20261026-fixes_shmem-v1-0-703206d5fa0c@kernel.org> <20261026-fixes_shmem-v1-7-703206d5fa0c@kernel.org> <2E377C76-D62C-4A2A-94E3-ABC40C6FCDD2@nvidia.com> <583728ed-dc63-4685-9ac5-5a980db55973@kernel.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-MS-Reactions: disallow X-ClientProxiedBy: MN2PR11CA0020.namprd11.prod.outlook.com (2603:10b6:208:23b::25) To IA0PR12MB8374.namprd12.prod.outlook.com (2603:10b6:208:40e::7) X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: IA0PR12MB8374:EE_|LV2PR12MB863586:EE_ X-MS-Office365-Filtering-Correlation-Id: 6ed2f788-9e38-4ac4-9efe-08df33b20fb8 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|23010399003|376014|7416014|1800799024|6133799003|22082099003|18002099003|261026140227099003|10067099003|4143699003|56012099006|261021121427099003|11063799006|261009223027099003|261021123027099003|261022105027099003|261026121527099003; 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:IA0PR12MB8374.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(366016)(23010399003)(376014)(7416014)(1800799024)(6133799003)(22082099003)(18002099003)(261026140227099003)(10067099003)(4143699003)(56012099006)(261021121427099003)(11063799006)(261009223027099003)(261021123027099003)(261022105027099003)(261026121527099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?ZG51bFBibWM3aVliUDRMY0xHOGxKYWhJcXRkR1NRdzlwVVcrcEgwaWpScTd2?= =?utf-8?B?QWg3ZmltWURsbUdmd3I4TXpWSkppTEZwOWppUVA4dGxEbmNyQ2RwalhlV21k?= =?utf-8?B?OGE0OXUyWnRHekkrZjc4WjRBbzZvS0RJSzZwQjBMQmxSWVc3b2UxZFlBNWcz?= =?utf-8?B?a1F4TlYrOXE3dE05MGtpdmMxWWw3T2tnWmQ2Tjd0VnVDZlRzTUsvbzlmZm1L?= =?utf-8?B?ZS90amhkRTI3RjI3MlNqVExicER6K2krMGdFb3I2ZjZuQ2tVcFJBZWg4QTl5?= =?utf-8?B?RlhGTkVTd1phaWZTSUVrbkFIMC9TaS84WTdyN2pCRWkrWkt6YXFIbjBrbGE2?= =?utf-8?B?WjBHUyt1b0FxWCsyMlRSUitjU3VBYmFhLzdFcEdWOHpudCtZMWhlaTUyOGFG?= =?utf-8?B?eXZJWUZvaXMzVElUcVNxdHhjbUtUaTdCSUF0ekFBdEN5T3kweHNpTGNoTUNh?= =?utf-8?B?SDFVb2FDZ1lxTHpFcmF5SWNheEJYMkxwalRhbUk0dW8rK1Q2a3dESjVFOTF1?= =?utf-8?B?dGZMdVNQcmRWcEM2bTUwRHhwcHN3MlZLUU5selRJczFWcjhqQnpxWFNRVkNP?= =?utf-8?B?L2FEWnBPNW5IOUtFZEhsWElCeHhqV3o4dGtxQTZOZ3FXL05wYnNST1IrekhY?= =?utf-8?B?VnlZbHBkVmMwWDdnTS8weE9OQW1CeWR4R3hCUkFmK2Mya2Q5YStyK25ZMkN6?= =?utf-8?B?RXh0c1JVVUpXUk4zM1padVh4eC9BL3hkUHMzaEhMMUQ4Z0RocFE4YlhIbkhO?= =?utf-8?B?d1J2YzJMdkJvajRaaU9KUFJldUJKUUxJejJEMTZMRXVQOTF0Smp3UjYvNm1L?= =?utf-8?B?cnVDWDZnU2lkczN1dmNFUWpEeXVvUVpJa1EzcW9RZXkybURSMzVZWno0ajBL?= =?utf-8?B?a2x5NGk4QVUrSEpmUEFDWUtGWGxTMmE3WWdQTmhlSW9CSEhuMHdSd3F5TVdZ?= =?utf-8?B?NzdkN1Nmam9GNm8zQVIzY2ZsRCs3b01FdVdXWGZPaWNCRS9OMDJ0aStjU0hm?= =?utf-8?B?WHpxbjNlcGJyclQ1VzlhcmZIclRDTkN4VlF5RksySjFmenc0bmdXYnJRSWxZ?= =?utf-8?B?b1BaaGk1Ry8ycVNKS2pPN0ZtbEFmazdYMGU2QkJWSWNtODh5cGtMNVRVa3dX?= =?utf-8?B?U0t3bllVQkJyMThsSEdGbXBZM3pNRUpyQXZ6b2g0S3NzcG1tcjVyOENZbXd2?= =?utf-8?B?eTY2UDlCSzZMVkpXMkJlN3Roa05WaXd5ejkzYnQ1RE0yVUs4U1dOQWJ2TVh4?= =?utf-8?B?TnBVR1h6aDRFenFrVnp6TjZweXh2dlh1d2FTOUhvMEltbytsWFRObHh5WXJB?= =?utf-8?B?NDNKRmYrVitSeTlnQjlYQUNhYXlIWDVXRmJoMm5QWGV1dXc4bzlmQ3RKM0Zn?= =?utf-8?B?VzM2M1pQWUI1UVBsbEtrMk5VUTNwNXlmeDB0T1lvOUNLblRNcFBqZVhsMjl2?= =?utf-8?B?RFZMblVqT3dUQU1nTGtyQW9XZ1A4OVhQU3k3Vi9RL0pMWHQwWDIxRmFjQ2ln?= =?utf-8?B?SENQRnNDa3FNZk5xVXpvMHdlcDZvaFBqc0VOQnRQdnZTYXRCQmc1MURIVnRn?= =?utf-8?B?Zy9jVnNSQXpTUURra2Uzd3Y0MzZvTTRISXhrdk96QjVKa3hCQm1aNVg3b2dp?= =?utf-8?B?N21TbnlpcFhOUUZsaTh2dkdiYVZBV3lhTnpoV0VDdytRcEYvaEdHbmZEYlBv?= =?utf-8?B?NGF4NmY3SVQzbk82amVwVXB2bitzanFmajlJTWVqM2haelJyTDlqTTRjYk9E?= =?utf-8?B?MWQ3TnNaS1J3Q05PZ3JzZzVyMFRiS0syaUNWR3MydkZFL2FBbnhkdUhyWDNB?= =?utf-8?B?RzZEcWVaY2kzdE9JZThpc0RJMjhkQ1lVWWdqbTRrQVZlaFlsTUkvT3pNU0JO?= =?utf-8?B?QmlpUjJqMFJxWSt0SzNVY3o3QnpCVThtbmdsV3N4dU5EQ2R0am02UWp4S0NP?= =?utf-8?B?T3JBMnpOOVE1UlFwWDZEc0k2aTFlUnpmVDBvTy9WeWFtaUd6eVIxWXl6WXZa?= =?utf-8?B?TjdFNEpqZ3Z6TDdvSWhqNGw0RERnT3UzamdMT0JZaS9oZnFkTEJYV0xQajds?= =?utf-8?B?WTJnSG1sSENyR2I0blRUVWx0U1pFQnFGWStnbUw1NHNGbUM0SzYvNHUvaUJL?= =?utf-8?B?eXZvT3VCYmNrcTZpMjNFYWlVNElocDdtYTBMN2lWbUVBYUt4dTZvN09YaFpY?= =?utf-8?B?MkxEOWRURzROdlhZR3lKaGpNYVB1U3MybXFEVkIrRzFuSjNrSkZkdnJpTVJG?= =?utf-8?B?THo0MUZPMllPWU5nNzJqa000dmFJQ2dDQlRsaFM3RG00WXhabVd4M20zbG42?= =?utf-8?B?N3dFSmxsSkI3bkxCc1VxaytiTTRscEFZMUFnMm91NGl2R3VmSitGdz09?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 6ed2f788-9e38-4ac4-9efe-08df33b20fb8 X-MS-Exchange-CrossTenant-AuthSource: IA0PR12MB8374.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 26 Oct 2026 22:39:57.2206 (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: Io7Q/vNr8VWLBfQfL+QwRsTpt2s4VD/NiwHzWzTupiCm6hvEtZJlxS6Eq5OlNYVj X-MS-Exchange-Transport-CrossTenantHeadersStamped: LV2PR12MB863586 On 26 Oct 2026, at 17:13, David Hildenbrand (Arm) wrote: > On 10/26/26 20:21, Zi Yan wrote: >> On 26 Oct 2026, at 5:40, David Hildenbrand (Arm) wrote: >> >>> From: Chris Mason >>> >>> A nonuniform folio split can fail with -ENOMEM after splitting off some >>> smaller folios. shmem_undo_range() then sets start to the end of the >>> original folio, which may now lie before the truncation boundary. >>> >>> The final scan can consequently discard data below the new EOF, or >>> keep retrying a large folio whose split point lies outside it. >>> >>> Keep start at least at its original value when skipping a folio after >>> a failed split. The part in the truncated range has already been zeroed= . >>> >>> Fix generated by an LLM and sent by Chris Mason in private. >>> >>> Fixes: 7460b470a131f ("mm/truncate: use folio_split() in truncate opera= tion") >>> Cc: stable@vger.kernel.org >>> Signed-off-by: Chris Mason >>> [ david: split fixes, simplify descriptions, adjust comments ] >>> Signed-off-by: David Hildenbrand (Arm) >>> --- >>> mm/shmem.c | 8 +++++++- >>> 1 file changed, 7 insertions(+), 1 deletion(-) >>> >> >> This is fixed by Zhang Yi=E2=80=99s truncate_inode_partial_folio() fix[1= ]. >> I think the commit is ad27479793682 ("mm/truncate: fix data loss >> when splitting straddling large folios fails") in mm-stable but >> not upstream yet. >> >> [1] https://lore.kernel.org/all/20260928120833.3440834-4-yi.zhang@huawei= cloud.com/ > > How confident are we that it fixes the same issue? The issue here is that folio_next_index(folio) used in the mainline code can be an index lower than lstart and the fix is use max() to prevent start going backwards. (I wrote this to make sure I understand the issue correctly) Zhang Yi=E2=80=99s patch passes start into truncate_inode_parital_folio(), which has a new signature, and it is updated with the folio=E2=80=99s index within the [lstart, lend] range at the beginning. So this patch fixes the issue at the caller and Zhang Yi=E2=80=99s patch fixes the issue inside truncate_inode_partial_folio(). > > Does it also cover #8? No, patch 8 is still needed. I am checking it on how to rebase it on mm-stable. Patch 9, 10, 11 might need rebase on mm-stable too. Since these patches are on top of mainline instead of mm-stable, you will need to rebase them. IIRC, Zhang Yi=E2=80=99s patches are needed for ext4 + iomap buffered I/O conversion. Hmm, but Zhang Yi=E2=80=99s ext4 iomap patches has landed in mainline but its dependency is not. So we cannot drop Zhang Yi=E2=80=99s patches and ask for a resend. Adding Zhang Yi here. Best Regards, Yan, Zi