From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from MW6PR02CU001.outbound.protection.outlook.com (mail-westus2azon11012050.outbound.protection.outlook.com [52.101.48.50]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C06E04071F5 for ; Fri, 21 Aug 2026 19:54:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.48.50 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787342079; cv=fail; b=hmLFF3fsBfRUYutpcZ97qhAyvK0O64eOn0PYqa7GiA/T9QveLoXZrLkN0K4VlebUJoQMLJaxKd0cGhMu/oP6gwkEibn+EECdGRDhvDdd/YEHvzAarHgsAwBDAjDUpvIejLe5Rbj2bG2IIrthiNTTVfkl+fXJ4r/3dP7kEjrvAJQ= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787342079; c=relaxed/simple; bh=VHoMrq637CNyTctOjL58JkakYcpV/Wv5A5HTwk90nHc=; h=Content-Type:Date:Message-Id:Subject:Cc:To:From:References: In-Reply-To:MIME-Version; b=ZC3+O5mlMpwXvPj+ndd6G3cRtGEOk6UNiUIi5IeXm27EVUDRpqUGPPaB+nsfoYghZDJX6nzE4Xl47VM0LqRie42K7BgCPageBQpgHKYMwZ7h7AJXV7oCTvQ+n17bz3xcXoI39/C+y6aSxdPE46tc9LsWgHh1FKXTLkqhJdXCBlQ= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com; spf=fail smtp.mailfrom=nvidia.com; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b=OBgX2QV4; arc=fail smtp.client-ip=52.101.48.50 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) header.d=Nvidia.com header.i=@Nvidia.com header.b="OBgX2QV4" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=JYaHQwPm2YUN6tw8igfuHunT1i7oWZId+QPyyW5JAoiDD9gDDDQS5xaHzTJKJjtm5gED9WEVCjrCpc3bVuu5fIrK8Rojl61mAYCO8Se/2OMnlWeuNIZXQApPiUAM06A1WT0R3gla+eKLKaPkS2LfO39/fpW6x7aMPC4aFSvNyeJGNh/vFdlkrYzRUwvbSg8OVmt/v4tWdfHqawjXyE3+dkJMPWg4UQyrzYo0LXOUoK8aAzCOGj042XNWPs5LZz5EMJAXU3WqDk523dNQ0DjWY1AiKk4ZQcKIdfuXBnGeuX6KcMOk9j3tGNxVwI3/c6eGPu80KD8zVkyw60EXMElwNQ== 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=Kfn2XNUnQhNk/50hnbJn7Uq+DCj9mkY9VT491kqh7fo=; b=OGbj1ki32MidXRGVCMcKnnwnYZDRm3T24pyWCv1IICTN5IgifD48wgaX4VaNmRjX6gP4PBcy9n8V5gp0AwOq62WpSUX2inkCQ2Wt9j+tSShpnTFGQXq6jmACi7SrxMkuNftpxQKLCNi48s48EGbOhSjIpYwj5LcSgZ9sQrWbj5oJBxUMw8ItzURbe65W3IBQsBczyELA1ejQ0I+KGbiVNhUupssbGK+hENBeCjJyyVw5MSXBIf93OR1CwdyNGTX39IZdNvjp5gCgoYj2VIvSlyCONM0MdPDHvP0rr/apIgcT4tbrePdOTH2kHLMfvSnbe1/7NLapn0+u3dSl8VxXuQ== 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=Kfn2XNUnQhNk/50hnbJn7Uq+DCj9mkY9VT491kqh7fo=; b=OBgX2QV4tgKu7Vz9jAjdMDG6TCEhtDile2mmKr5Z3aBOdcoinSmNVX82ePxfznPg1Bwh6Ew/SbGwN47bCxbnhLXToHn/2hjv1pL0JMCSYUVI7ecFOw0lvYq+ual553ZdjaXyRobJYlkKiQAV8TlTrj5rAihlgF5RySmCn6H1RsvXtKSFHmnBNgI0rn/YP6HI7NTytfQJvgvf9sa477Nw8Qftj6k8mcg0JK9Hk/kNYDUAg37g1pfEKeHzHj80ttQHHjtPvIlkkfLwvCls/XeQB428e+3mt0Nybk1VWMhLdUNOcswNWjZkwCp8x6slQMnj40CObmUbWRiUQvH0fqiTvg== Authentication-Results: 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 EAYPR12MB999157.namprd12.prod.outlook.com (2603:10b6:303:2bf::20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.339.11; Fri, 21 Aug 2026 19:54:34 +0000 Received: from IA0PR12MB8374.namprd12.prod.outlook.com ([fe80::d85f:4c87:ae84:3f16]) by IA0PR12MB8374.namprd12.prod.outlook.com ([fe80::d85f:4c87:ae84:3f16%5]) with mapi id 15.21.0339.010; Fri, 21 Aug 2026 19:54:34 +0000 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Fri, 21 Aug 2026 15:54:33 -0400 Message-Id: Subject: Re: [PATCH v2 2/2] mm/page_isolation: guard compound_order() against racing Cc: "Suren Baghdasaryan" , "Michal Hocko" , "Brendan Jackman" , "Johannes Weiner" , , , , To: "Qi Xi" , "Andrew Morton" , "Vlastimil Babka" From: "Zi Yan" X-Mailer: aerc 0.22.0 References: <20260821025501.2752563-1-xiqi2@huawei.com> <20260821025501.2752563-3-xiqi2@huawei.com> In-Reply-To: <20260821025501.2752563-3-xiqi2@huawei.com> X-ClientProxiedBy: YQ1P288CA0020.CANP288.PROD.OUTLOOK.COM (2603:10b6:c01:9e::29) To IA0PR12MB8374.namprd12.prod.outlook.com (2603:10b6:208:40e::7) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: IA0PR12MB8374:EE_|EAYPR12MB999157:EE_ X-MS-Office365-Filtering-Correlation-Id: 6311d4e3-6a3e-4d90-b60e-08deffbe0638 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|366016|376014|7416014|1800799024|10067099003|56012099006|4143699003|11063799006|22082099003|18002099003; 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)(23010399003)(366016)(376014)(7416014)(1800799024)(10067099003)(56012099006)(4143699003)(11063799006)(22082099003)(18002099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?VCtkRk95M01VVWNuTmpycnNHbXdiQkVDOVlSbzlnYjB1dng0WmRta095NHdX?= =?utf-8?B?VjlocTl6eTFhQ2toMHdpL2ora3Blc1ZRTng5VG1FV1FmUHA1N1lRelppcmtS?= =?utf-8?B?eGNWMEFqaW5CVENrWWJHZTY3SnQyRnh2QlBtcW1JeFBFQThlKy9xREs0OTEv?= =?utf-8?B?MHh2bjV5M3Z0ZDU3Z25iNkt6SGltclg1LzhMV2lOb1VFTkM1NDRXRDBLZXlH?= =?utf-8?B?YXRncjdxaVhKbWJlcmtPd0p0bVRCalQxZDF3UUFVd2UxNE13RU0zcTljL0RZ?= =?utf-8?B?VG5LR014NFdjb0xQeWxhWE1mRGU4T1k2WEd6bXV0cG9ZcXlTSXozS0g0UjBz?= =?utf-8?B?MVFFTGs0OHFabTQxR251QXJVVmF2V1N0QWp4ZEh6T2V0SlZabytYSnZCMGZt?= =?utf-8?B?aG1kNDkrc3o3WnExN1ZpVW84Y3VVY2llbzFBbzhydDczUHVITXlneDBjU1lT?= =?utf-8?B?NHZXdU12K3pkM2hyeThpZEJRSTNqY3d0MXhuQVlObnBvNkZTZldlbEthc1pN?= =?utf-8?B?TEpnaithemhwMHd2ckE5bTRmVGhVK1NHc3BxbjFYQ0hySWhoRzlKYUpvaEUv?= =?utf-8?B?d0t5bnF6YnhiZGJ4ak9DQkQ4NDM2bG9XaUt1NWh2TzU1bGFQRUpZZlNQVS9G?= =?utf-8?B?YXRvb0MvTHJzTTIxTWh3Y3E1cUJtUjBBbkNXS0s0emhZQWhSRXppdExTZGR4?= =?utf-8?B?WWJnbEl2ZWFJV1RLRmcrQVA0TVZ1VmIzRENpWXBhYlhGR1k0TVVISEJjVDdK?= =?utf-8?B?OEZDQzlvMHRYUWhGQVVMeG11NmFYdlBDdDZISHR4VktDTzd1Yml3alcyUHc0?= =?utf-8?B?eGRtd0pBOEJJWmpqQkpjTFAwTHFsU3BCTnJRRVdDVFBuRVJlODVYSkF4eXJr?= =?utf-8?B?aHhncTRTdHZJdlh5M2h3ZW81RTRXVDFOVWl4ZEJHMURNalBJcWpsbWRqL3BY?= =?utf-8?B?UnJrRUFSZEJ4M0lTOEh2Ull6eElTVXVXN1I1cG1lRk5aNTRXQ1ZSZzBIbnRO?= =?utf-8?B?K0d0Zm9OOTFzcHMwTGx4aFdtMGZkcm5UeG1yVmJDUFU2WlBsdjdkYUo4WHI4?= =?utf-8?B?YUJlNVlhQWV5MlJ4NUVTbjNZNkdlanhBZ3l4cWZyQTlxanFzMS9XT2FTNjZN?= =?utf-8?B?UUJLMGRpN2o3Wld1YmRKdk9NVDNETTdKbE9DNHhMblN1MmVZT1FidkM5dHRM?= =?utf-8?B?RHpiVDBLTE1WajFIM3k5azVSVkNuL3NrL1hQaTlSNWVQZTFMcy83QUJNQXFt?= =?utf-8?B?NTQyT2c4WVdFUFVHbUM1SU9uMDl0QnNmM1NyUzFZanBSUFBkVEZIVW1hRGdy?= =?utf-8?B?VzFWby9RSjV0YWdhZ1VlR3p4VUY4di9UUzF6OXlSTnptMXdIdHlDcGRHdTFp?= =?utf-8?B?U0NjSXVreGY0Y3FnUGExS25CdWZlM3JSeWpqaWtRWWNSVlYxOURKSzZNNWtl?= =?utf-8?B?N2hJVS8rOXR3UXQ1SGhBV1FDeFh0WU9vZU9LODd5SmtVQVFBVnU0QVdvMmlZ?= =?utf-8?B?UWRkMWV2bFlwVklGSEhFdUFJNi8vMy9ERGR0RTI3WWNmbFRWU1k1Y2VralM3?= =?utf-8?B?eWFobVY0OXRvdFdlWHFKYjN6b2UwRGJwcGw0R3J2L2o2YW1CUTVMNXp2VTNt?= =?utf-8?B?QlNNQ0l2d0pLTTJrSXFBYUtPeDUvSnhMK080NmN4TERVNEM0c01WY1J1c1JQ?= =?utf-8?B?R2J5aGhhb0wxUVFHck5UOUJRcklCQmdGSisvMjhHNUhjdkRVRzZ2NWFNOUFk?= =?utf-8?B?Um9PM3BDaiswWEZkNjV3alI5SXF1UHNPQTltUytDUHFvR0JESml6ZjMzbjhF?= =?utf-8?B?c2NPTlZTNzdzaVZRNFFPalpYcGhRbjNrNDJhSmhuRDZVaHFORFNOR0d3OXN3?= =?utf-8?B?NXRnb3NzWm5mWkhBWThWWGpXWDk2VnkreWhEQWJRenZQYktMR0NQYUtwRTN1?= =?utf-8?B?R2VoeXhWbUpGOXpSSzJqNER0alBVVE5ISFA5bFZRdmNPR1U2TnM5OG9Cbkx0?= =?utf-8?B?K2Nua1h2blRvb1JGcC81Mm5UOVhVQTJtN2RGazNTMnRlWVRVR0hEa0IwN01q?= =?utf-8?B?Qm1QckxVM0pvcEZnYTNidHk3dFFPRDdBSVp3QUx0QTFQOFZ6RFhoM3ZWb1R0?= =?utf-8?B?ajRJQUlRU3ZMZENPRU1RbzU4QXhWWmYzajRWZmNnd0JuVTZyOFFZcndoYVll?= =?utf-8?B?R00wTTBXZUNuZ1BKaGxnYVdhNWVlWEpITG9GQ0FwL2oxKys1SmEzQ3BxQ2pN?= =?utf-8?B?TjZlTEwrdk12ZWN2dWQxV2tKN1FxVTNJU0ttaEhsUlRlSENQQlpKOVVJYnNO?= =?utf-8?Q?AIILZKnb9yeUrkZNZt?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 6311d4e3-6a3e-4d90-b60e-08deffbe0638 X-MS-Exchange-CrossTenant-AuthSource: IA0PR12MB8374.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 21 Aug 2026 19:54:34.7639 (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: TTpIOzgIqRXCV3GCwZ69fA3ES7d+BUR0zrmG8mG08W1L4HKDRMbYhVKLyoH6THMA X-MS-Exchange-Transport-CrossTenantHeadersStamped: EAYPR12MB999157 On Thu Aug 20, 2026 at 10:55 PM EDT, Qi Xi wrote: > The PageCompound branch reads compound_head() without holding a reference= . > A racing split or free can cause compound_head() to return a stale pointe= r, > and compound_nr() reads the order from that stale head, leading to > out-of-range shifts and making the skip distance meaningless. > > Read the order explicitly with compound_order() and validate it is within > MAX_FOLIO_ORDER before shifting. Also verify the derived head_pfn against > the legitimate pfn: the head must not be past pfn, must be aligned to > nr_pages, and pfn must fall within the compound page. Bail out with > -EBUSY if any check fails. > > Fixes: b2c9e2fbba32 ("mm: make alloc_contig_range work at pageblock granu= larity") > Cc: stable@vger.kernel.org > Suggested-by: Zi Yan > Signed-off-by: Qi Xi > --- > mm/page_isolation.c | 22 ++++++++++++++++++++-- > 1 file changed, 20 insertions(+), 2 deletions(-) > LGTM. Reviewed-by: Zi Yan --=20 Best Regards, Yan, Zi