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=40.107.201.11 ARC-Seal: i=2; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=pass; t=1793810350; b=t7H07H8uOUerRrHUzoLnvRemZVRiGPtSD0NBzMvpjAaVzy2qralqsCnGiu/fu95VXg0d VJmlRJXb7hdIJaU/3jmXK4dV+/DV14uc5bpzWL/W7KOW0mv64sU0rv/FdUs40/mpCARDq zxxXVBEkN6fD52ojnj/ek9kw9A6FFbeYXcByuH6dn3hGDzT+WHRQQ3ZOPoq7DiWs7hSIZ mNWOTRa8BfPrHF8bTKFPQRxCSKnCkn5wEEhhxoInFk/DsX61azX0DEILVJ0bOSmKZp1Wl c25dnogSc0eGrGYwIUOfSpWVNhjNg5aI3W7U4AITvws5bE2wQVfJ3CeU+577q/UmIVA== ARC-Message-Signature: i=2; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793810350; h=DMARC-Filter:DKIM-Signature:Received:Received: Content-Transfer-Encoding:Content-Type:Date:Message-Id:Subject:Cc:To: From:X-Mailer:References:In-Reply-To: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=S7uzjATlcBgQ4C4QznzH2i91eUNhhj35MPUel0ON3OE=; b=IgVHaVVxSFgCOVjWlFXCj7HZVdTlXn6adkGUK9P8dE9xO43ejPNzDNV8ejHoB6AbZnAz Ji/nq7StdZELexDHyM80T/yK16qyfTbhXuT8bmYENRNZqBhE+VZqL/guRkTHZvQuDJuwu a8aJIoet4h9GUiD+nNDKOMRoKFDMG6HsC5vnUiLIrmsCHYWnx1/dq357Hr//fga+USpcb CKdqCmrkyT270P4+MzLTb+8mYw97yn1a2jH1qaOyAhyaWX3l8L8Me7GZhHA6VvsrIPL+N 8bzkbjXmq+ganuSxHGEPYnqjkPs/ZtRvPPoi9dqKH1sWaJ5MjWKFPqeAXspHeDzo2rg== 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=ZFS5wUhr; arc=pass header.oldest-pass=0 smtp.remote-ip=40.107.201.11 Received: from CH4PR04CU002.outbound.protection.outlook.com (mail-northcentralusazon11013011.outbound.protection.outlook.com [40.107.201.11]) (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 8B2C5606A330; Wed, 4 Nov 2026 16:39:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 8B2C5606A330 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=ZFS5wUhr ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=mUqEmO/FMG6kDtyvzlgNNBwrOzBBHS6mpIDVWcQOIoJmOfROSdyaudJChgi/z+HC9NJmzqAc6+n6L0aDlaGsDYobmRLm47KLeL2UxgUgaSdp4c+ymu9zvY9UpxnK7QuzawJBo704D79OkUz0UOtn0hLHVmZfSXffhqBFBfQDV9OIgPwrtmfi248lG2cxA/IiRB0wrjkfLxxRMov8ikxSvwOe2kvoS/ZtzkukxoVq9UM8lWgdMW3PnuDiD8aNyERsw0Kt+DFIdM5f8WR0eDHYjDLPLkuuK2LrTgu5JEvmJhV3e2EKlwKQAq6e7YGzAIKT8WR0wRwXqXXJPTPyVP2HpA== 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=S7uzjATlcBgQ4C4QznzH2i91eUNhhj35MPUel0ON3OE=; b=JbevP5ImN9qsNxzpIWppg8fZoNVjB9eDCRYERhmrEk9H6a8mUZOc2jZOCPu3xjcFSLGmRjWqKaO0cfl1EZA2NFZKa1ECbGU3AEcw8voQE5M4SRoYpjNTYKwuBQ2gZqXT0xy3M+BcqrEKT91f6cmxKEa+GKhJlFeU/hkzCAalkfUxbJ2p6CuZYAAq8nSZJW8caq6sPZ6zUlfZ6tky7uex0QGwwbvlAFLzAHOaAMf391r3GLWfjN9myLWSLhB4xUWEwHB14JRze55DGj/vuwYy5efFcLSh4T52BxN3gCWHbfRlS/Qod7+530Flwjtt7YgmWb7W1/ESCHTqSzzPdUlOsg== 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=S7uzjATlcBgQ4C4QznzH2i91eUNhhj35MPUel0ON3OE=; b=ZFS5wUhrk4+Sq4EwJ4oI7MFWazTCghwDgo45f8wlSFAjpayU54/l80gRe+taRcHT2fq/iUEbQkSC/ePdf6U3Y6Jh/Nt+oU5tQIXHKu/7cJVcNqWdlyk/mDYmektsTwJ9nMVmm2bo5T41fH73KgX8oq0Z4j03Kbk2Z1UL1ivZinhbSdamzINWcz0jYDfmEc1gwILJH4wyk5CCwqQg9V95ZqZeUFpriOBT4FWMoTNE44dn3wZqN6zriWySmCmcxEtXdVXemzV+i+cbS5LkSdgAt4D0eXrMfcDT0yIcsx9gz5SdBAYyzG56pyEAglmSbSUMeXddbOtUWsZxbIOv1AZ1iQ== 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 LV3PR12MB9119.namprd12.prod.outlook.com (2603:10b6:408:1a2::9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.592.9; Wed, 4 Nov 2026 16:39:00 +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 15.21.0592.007; Wed, 4 Nov 2026 16:39:00 +0000 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Wed, 04 Nov 2026 11:38:57 -0500 Message-Id: Subject: Re: [PATCH 2/2] mm/page_owner: also check PageTail before reading memcg_data Cc: "Tao Yi" , "Johannes Weiner" , "Michal Hocko" , "Roman Gushchin" , "Shakeel Butt" , "Muchun Song" , "David Hildenbrand" , "Matthew Wilcox" , "Baolin Wang" , "Liam R. Howlett" , "Nico Pache" , "Ryan Roberts" , "Dev Jain" , "Barry Song" , "Lance Yang" , "Usama Arif" , "Kiryl Shutsemau" , "Vlastimil Babka" , "Suren Baghdasaryan" , "Brendan Jackman" , , , To: , "Andrew Morton" From: "Zi Yan" X-Mailer: aerc 0.22.0 References: <20261104-kpagecgroup-split-v1-0-f70e947fec85@samsung.com> <20261104-kpagecgroup-split-v1-2-f70e947fec85@samsung.com> In-Reply-To: <20261104-kpagecgroup-split-v1-2-f70e947fec85@samsung.com> X-ClientProxiedBy: YQZPR01CA0037.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:c01:86::7) 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_|LV3PR12MB9119:EE_ X-MS-Office365-Filtering-Correlation-Id: 65c63abf-e10f-42fa-8284-08df3a9220a9 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|23010399003|7416014|366016|1800799024|11063799006|4143699003|261021123027099003|261021121427099003|56012099006|261102123227099003|261028144727099003|261022105027099003|261022075727099003|261026140227099003|261026121527099003|10067099003|18002099003|22082099003|6133799003; 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)(376014)(23010399003)(7416014)(366016)(1800799024)(11063799006)(4143699003)(261021123027099003)(261021121427099003)(56012099006)(261102123227099003)(261028144727099003)(261022105027099003)(261022075727099003)(261026140227099003)(261026121527099003)(10067099003)(18002099003)(22082099003)(6133799003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?cGp1Q29tdGl2ZFlOT1dvNG96ang1bWxOeHlodDJjM0I4MFBmeklJeWhVaW4w?= =?utf-8?B?dEZWZWg2bE1GaktINUsza2MzNjlDeFd2eTJlUWllbDdGM2NQWTRYSkxOLy9M?= =?utf-8?B?Y2NGTFp6dy82RjQrWHMyNVd3WHBKZm5WcTdXelQvMFhISkdDZm9NakdBeTd3?= =?utf-8?B?RlVUakhrdSt0ZzdyU0xrTEVFY2plaEkyZHlaZTV1a3FHcGNSQ28vNWFTYnMv?= =?utf-8?B?K0dwWDVtZmMrZmNBdnRhZVFZQjJCS3FQMTZUL2lpZFFyOEppNVVEV0s1NDhC?= =?utf-8?B?VHJ2WmJNZXNXakhtOHFnY2d2Vnc2bXRJVmk1Z05qZmZqenpjS3ZYMW9EUXFT?= =?utf-8?B?R3REZGRHbENBR1oxaHRuLy9sN0lyTm5WN0d2L1pNcVlWd1htNk1mN3RsZWU3?= =?utf-8?B?cVZTOGdkZXhFZmUvS29xQU5MVzZhd2FuS2ZRbVZtMTM5UHp6QVZKT1g2MTc2?= =?utf-8?B?QWJoZ0ZKZHZoQU8yaEo5ZGxINGtZTURyL3JkT0hrY2xmOENjbEVjczk1MnpF?= =?utf-8?B?cWhEdmlHMnJsVE1DWFRmSnIwNG5VNWZ5NTJXanRsZS9NckRnQXEwazRsS3pP?= =?utf-8?B?ZXFJL1IxSmp0ck04b3pUNTZJc3FnakNzc2dCY2FOT3dtNm0xNWlDRjBWdzJH?= =?utf-8?B?WWtqTWsxQWtDUWZyYzVPMnFraldmZlo1SEtERUxXWUFTRjhheFhhalVubkJC?= =?utf-8?B?YkhiQzlVMWhkdytEQ0RudlVqL0xNZ2tqcHRKbzZRMGhTT3JMWXIzMkJyVGdk?= =?utf-8?B?aGxqNjk5bDRPWkNicDRXYVpHR1dMMjM1QzhxcHFCTkZMdGdGNmZBMjVjaWhY?= =?utf-8?B?bGs0M0VJTXdxQ01uNVRqNG41RHNTcGpmZm4xNVBFWEZaNThpNlRHL3hvQnR0?= =?utf-8?B?SGdkVHozYThoaGlucVRuM2M1cFliYXp2MHl4a1FieUlDK2V3ajdqLzdqY1Z4?= =?utf-8?B?bWxBbDBkYnppNk9KZXVsM05CaUR0U1Uxb1Foclp4WmsvNVBITDdFRG4vT0JL?= =?utf-8?B?QjZDdEthKzdkYVNRUTZrQ0dKNFVCSEJteXlMZ3dSWC9ob0hmTlNaS0htanJw?= =?utf-8?B?WERxUkhKSUlaZWNPWXgxR3FoMnhQVSswTjN3WDI2ZGRBeUNBTDNxTHVLSmp4?= =?utf-8?B?N2ZrZDlaWWl1VDA1ZE9HaTF4YlQzZ0FUWGJWZXk0RytkRVp2WE9jZHFnZUho?= =?utf-8?B?T0JpU25veTU1MEV1OWMxZEx3VWJ5c3JyckNFR0szMGM0SlNBUUVvRFpsM3RI?= =?utf-8?B?VllvbVRrZnhYem5LcWQzOE5VTk9ONEhKdEQxbTNucFEzVm03NFUxOVVLaUFI?= =?utf-8?B?VUY4dnhTVldTaFJHbi9LTnJ6eWVaWG04eGxHSmhNWDFMKzJYZjUzL1dIdkNP?= =?utf-8?B?MThZTTZZRWlvazgwUkVtNXFKLzByMXVCTENlL3NhY0JXOC9kUEhOemZrYjFT?= =?utf-8?B?L3AzUEZPUTk5QmVpVGk4OG9Xb3ZVL3dDZUEwOHZuR0FJcVBzYW9RRE9ZTGRL?= =?utf-8?B?UytESEI4Slp5L2N1eWJBV1V0QzZNTXE3bkk1NnlFMkh2YU9xMDFzNlJ5Vldm?= =?utf-8?B?TE4zRU5pQUR4czVzNThZTUp4SU1qaDU0UWUxVWd0ckg5Qk1rbm1CZkcxejhI?= =?utf-8?B?Y0t1OHNacmhXN2M5WE91R2g2QnZKTVdFQnN6aVJrbTlsTDR1bmd3ZEZMTStj?= =?utf-8?B?OWY1U3FOMDN6UEJjS0Q0cldqb2d3YnRPWXBLbWxqZXlDczhIQzV5TEZPMm9L?= =?utf-8?B?QmdURklPR0tMeEVXVzN1M1h4dmR1WTRTSTJ3NTI0UkhIWDFRSU8rc2U5d1lB?= =?utf-8?B?bXRPdEttTlMrM0xLU1ZHcmo0VlhiNXdaejBncEZ2K1pMMSs4TXhtTmg1VWt3?= =?utf-8?B?QXFPdU53Z09VT3I1SyswMGJxVlQ3ZWtsdmtDejMyRHRiWG0wMnFVeUdpbmFq?= =?utf-8?B?OWFQWTNKR0oreXlqTXRtSzBrWGl4RE5uVkR5Q29vSStxOGF4dnZRT2NPcndk?= =?utf-8?B?NGNVbnN0b0w1SG42b2k4MlRKdjRncnVIc1JoemJpcWtIV1ltbDRmYlFwdkU2?= =?utf-8?B?eEdaWTVUN3J1SFdUbDVZZitTU05FRzNidzlXdlltMUNNbGR6Y2kybUlzSWZJ?= =?utf-8?B?WUNCOEpMRVVmdlJrZFJxeUtHSFplQmJPL3ZzTlN3YllKKzYrSHRNSTRza29i?= =?utf-8?B?dkdNNFd4MjFTNkw0eDloQWExWEo4Y0RmNXduVTFQMFRpc3VDM2hGbmxtN2g4?= =?utf-8?B?WTRvSjF1ZUVxUXBVbWdZNmttdzR1MWVBQjFwdWlZd2lWT2RjWXdxMmh4WnN6?= =?utf-8?Q?ztyqipcRLVLxwdRNqD?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 65c63abf-e10f-42fa-8284-08df3a9220a9 X-MS-Exchange-CrossTenant-AuthSource: IA0PR12MB8374.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Nov 2026 16:38:59.8846 (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: RM3FVXbIYb6NmZRJUZhK/E0ZpjKzxBHuZZ6fc8XqWpagr/v4xqGkkV0WqmdNlmr9 X-MS-Exchange-Transport-CrossTenantHeadersStamped: LV3PR12MB9119 On Wed Nov 4, 2026 at 4:59 AM EST, Daejun Park via B4 Relay wrote: > From: Daejun Park > > print_page_owner_memcg() loads memcg_data before it tests PageTail(). > In the first tail page, memcg_data holds the folio's _nr_pages. A split > can make the page a folio between the two loads. The stale _nr_pages > then passes the PageTail() test and is used as an objcg pointer. > > __split_folio_to_order() stores memcg_data before the smp_wmb() that > precedes clear_compound_head(). Also test PageTail() before the load, > with a paired smp_rmb(). Keep the test after the load for a page that > becomes a tail in between. > > Fixes: 4996fc547f5b ("mm: let _folio_nr_pages overlay memcg_data in first= tail page") > Signed-off-by: Daejun Park > --- > Needs patch 1 for the store order. Found by reading the code, not > reproduced. The page_owner oops seen with a delay after > clear_compound_head() is the window patch 1 closes. > --- > mm/page_owner.c | 7 +++++++ > 1 file changed, 7 insertions(+) > Makes sense. Reviewed-by: Zi Yan --=20 Best Regards, Yan, Zi