From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from DM1PR04CU001.outbound.protection.outlook.com (mail-centralusazon11010058.outbound.protection.outlook.com [52.101.61.58]) (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 7BE653CB55A for ; Wed, 26 Aug 2026 16:45:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.61.58 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787762769; cv=fail; b=oPtZM8kDnXRR6lfRyV+DjRFbJdHjkoPOpWmL4ObR/Tv7Ph9tZyFztQ0/KnIfoQRo/35Po22EcCYWdfb8p0LrLFi3WnBGGp3HZoez3ml1R9fI5vaKsX+FNqbsefFACAPvdWHB+sBF+b5iyMngVzSvWK/6DhCmnPLqf23GKaDg638= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787762769; c=relaxed/simple; bh=3PPwu0n5FtYMqnEim1N5uN/ePfX1idzSdw7J1xdTWBQ=; h=Content-Type:Date:Message-Id:Subject:Cc:To:From:References: In-Reply-To:MIME-Version; b=OBS/NwDQ2wdT45meqPWBzLHXQGscPW+k1FNhSIlxLYbJAzaFI/CclkLgA2eELP/Kra0WyRzkLsO+RjOLRI1jIM3zkzE1KnwCCDrsgwP6jLBeygpanVjpk+OgG0I7AjA4k4Hm8I19vUYxhPn5PNE6e52I5sVoGObr01EV/7n3CHQ= 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=CJj1AsKQ; arc=fail smtp.client-ip=52.101.61.58 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="CJj1AsKQ" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=I/W6d31Wb/ck8MDIpPCO1XC2pQ8v3mVpg+DmXI5lAJlR81MOa9euPbwsu+TtmfvQbZM7XFgrbKCbiyQFJFN0/8YeXgwBedS2PPigqD4l5iiLK3xpb7iVJO2HAeVQNMvdo7voJ1OKRKCqk7MnQzmt+yzJC5UNVQZj7A5B0pDdULdM2ld4fOW22L2fYHspjr3BrepYvH7JY+GFLN12EEp6QCbSFk/hLJlK4JohbCGKLIHOEi1vJ3NNxGdGVkQIoXmkhWXWmI10SOhUx8yhkrxpeKRdm3aTDZoBJfwIIYDzXXgZ+Po8QCajcgyE6Y/xd43cmaWxnxo78e8N+vif0eBbsQ== 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=NUUYMidovale9j1gyJJ0rTi+LQ4pMu02wZ3xFBrC720=; b=gYSgDPzOAh+PWBdwN0GJHReWRsyfAy99v+N0K6LoRA83w3Fn8Sxq3z7Zml8Lwx/l4So0XWoRbEOgtmLDMf9qWqfGYQSkqPYGDX6c2yNU8EzLjexE8RZeg9jqVGcpRAllmpRR6ZZHuLoAuoMv10bmxqxQP39KlBvYqwwn9RKkh+/cHJjQhAsUbYgdpLFjOgloN6l0CSkuw1Cc50JdL15xKxfKy8gOxQOJamloE6KAvU3Rbc9laMBqHavXoJ6iQobGvffJDNlcRyq1nGb2ZUJpTLsvVyf4z1NFoF51jQSFelgtt4N+GmRtb8Uoh23q8mfzHZhovW/aMqaVcuKn/1jRZg== 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=NUUYMidovale9j1gyJJ0rTi+LQ4pMu02wZ3xFBrC720=; b=CJj1AsKQwYnN/POmz78O1ravycp+fN1SmhMWyZQ5KbEPu0bc7ikjB6gotZhmjgWkFKihspCZ/dp0dL/7iSvJY9Np0gFYTM5+PssnvyWCloJ3r4OyBh2++vxmOudHtMbv2J+gfjzMjy6Bnp6y7HrykWzUCgOM5oaDK7SHQknBMiTRyHPmtDpz6coXFq9jdQ6/ylwsCnqSd2md07onz/M+MTSOgtZok52CtlFvBotqD+ANsqVwiAHUJg9xEc0kisLk/DOM8r4uwcXZBvt2efyKdVZyMAeYyQyrCz2C+qaQCNMNFmEeSF+O/BloVPk3BhJ6fn3/yhQz98tfJ5nP40TemA== 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 PH0PR12MB7960.namprd12.prod.outlook.com (2603:10b6:510:287::12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.360.9; Wed, 26 Aug 2026 16:45:30 +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 15.21.0360.006; Wed, 26 Aug 2026 16:45:30 +0000 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Wed, 26 Aug 2026 12:45:29 -0400 Message-Id: Subject: Re: [PATCH 1/5] mm/huge_memory: do not touch frozen folios in deferred_split_isolate() Cc: , , , , , , , , , , , "Kiryl Shutsemau (Meta)" To: "Kiryl Shutsemau" , , , , , From: "Zi Yan" X-Mailer: aerc 0.22.0 References: <20260826162101.1314941-1-kirill@shutemov.name> <20260826162101.1314941-2-kirill@shutemov.name> In-Reply-To: <20260826162101.1314941-2-kirill@shutemov.name> X-ClientProxiedBy: YQZPR01CA0047.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:c01:86::28) 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_|PH0PR12MB7960:EE_ X-MS-Office365-Filtering-Correlation-Id: ee147d69-69d4-4acc-2ef2-08df039170c1 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|1800799024|23010399003|366016|56012099006|10067099003|5023799004|11063799006|4143699003|18002099003|22082099003; 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)(7416014)(1800799024)(23010399003)(366016)(56012099006)(10067099003)(5023799004)(11063799006)(4143699003)(18002099003)(22082099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?akZleVlxN0V4N05rSjRacG5ZdXNoNjF0eVQxN3dsYUtSMzJXelRMaXA3YWpN?= =?utf-8?B?aVd3VytER2ljbit2Q0FwUTZQVlpEcHkxWTVabjJ4R1k3UUFjUS9WQzdBL1k5?= =?utf-8?B?L21JUkhzSy9OcjQzTy92S3lScUllZDZad2Z1S2k2bW1rdTJVZ3QvNmNFenVS?= =?utf-8?B?TmkyWW9RUk1xT2hNSjVqZTVCL0g2N1drUEpibzBNL20vdWlqNGhrQWYvd3hP?= =?utf-8?B?STY4cTF5Q3BrZFJGQXgyeFc3SFVGOWs1UDJRcE1IaDY0N3VqRVZpZjdIUjVD?= =?utf-8?B?enYvZ1ZZU3p4cGxWNXh5a2xob0M3VmEvd3ZpNlVxd2xSOEd2SmwzcWN1dC9Z?= =?utf-8?B?MklTL09HaU53MUpTR1JlaGEzK3BOZ1NReExtbXVrV2ZyZWtsTUJkREVjZzdr?= =?utf-8?B?dit1NUZ2dHZTb29CQkcwYWtmL0paUzVkNDNSY1NoaytwU2ZLUFgyVTR1NU5U?= =?utf-8?B?Qzcvb3k2SkJCQlliS3BYRzlYSC8xSGVmOFRnbTllYTNVWEh3dUdOTlo5YXFq?= =?utf-8?B?ajByNEdWOVg1OTNCSXM1aEJnQ045elVtSTNDNkZKK3RlL1J4dWdMVy9TSEdo?= =?utf-8?B?UGh4azhXZEFrNDhqR2xCcHVFajZqMjBxYXRzYUFZOHRVNDVSWWFpUkJ2R2lu?= =?utf-8?B?YWhRMndtQnhnSXYrb1pUbTZCZi9qYXV0aUV6blNKMW9ieXFHL0EzcGNzdWdv?= =?utf-8?B?eG44YXZyNFoySDNtdXZmZ3ZyOTdzTEx3TWliNDU3QzZUcktuWCt1QXZYRHJq?= =?utf-8?B?QXFVeVgydUMyV2YxRkljWUMwcWU1bktiQXhDUnQ5aElrSFJvdDF4UTN3TGF2?= =?utf-8?B?K2ZzelpKYU1rL3pPTlZsRnhCbWwrOGgzU0xwVWR2WkF0ejE3WU1EUjBvd3dY?= =?utf-8?B?a3h5SnNCWkd6ZkhuRURhTVpvcndibG5YR1cyVzJxVTM2OXdnSjhCVGJzMU4z?= =?utf-8?B?Rm9iLzVGNTlRTVB3Ym5RV2pvQ3J6Ymc3bmNqWjJwRjh2NUdNaXgzUllkYzdF?= =?utf-8?B?ZW1xcC9EMCtOZTNCQkNMQUY0ekNPVHJ2ZXJCbWNZM3hKMzhJSG1IZHQ4T1FR?= =?utf-8?B?cUhCb0tqS1I5STlqRjFUK2lCRlVCbDNvekFENjJrY1RRdGlQaDhaRElWY20w?= =?utf-8?B?aGsrWXpvZ2lYNnF3cWlRaDVVc3B1ZDF1RnZhY0ZkTlZjY2VXL291TWwvc2E2?= =?utf-8?B?RkorR0txcDd1RUZiY1JhajI4dDNoVlpIUHRpL3pTY01tT3Qra0llRmNrbnlw?= =?utf-8?B?SmcwK0wwTlc5RHIwVldNY3FtRkNLck11S01TeHF0Q2lGY1V1czhzZHFkN0lk?= =?utf-8?B?dXM1elZRdjRzZ2VEeUZMeTNaRjBZdTVHMDI3eGxkT083bXI2VTFnUEtRM1NB?= =?utf-8?B?NzRIVjFvNzJZWng5SU05WUhRejlTMkZTZVRxUi9GRksySWRZQytZUzJ1QUdY?= =?utf-8?B?Vkl1MStTMjlFdmNRNWd3Um1RVXdmSklscDVBM25vQkQ2ZkJYeTl4S3lkK0Nw?= =?utf-8?B?dW1uRHpaWWdyT0NDaEgyU1g5bmoxbHFQSy9rVCtiN1BHNVJiWnA5Z09BUXpL?= =?utf-8?B?TVNRelE3bU42S0kybnhiek9UWE5ZSVljMHBSb1BDUU9QVEVHUDdLV2h6VXV5?= =?utf-8?B?WGlKOXJRVWY0MGxuWGhzRVNmQWt6MUNOYU9CQ0gyUXBXTlYvZXY4M05leUpm?= =?utf-8?B?OVdNWk4xL3pUNUdPQWQ2TytqeU4yTCtGRHNDVVpvdEdhbzZSbHgrRWdKVVNQ?= =?utf-8?B?RU1tKzhlRURRMk1MWXFYMWlIZGE5OVE4TzlTTTR2QkxKQXFGTytET1RPRzFn?= =?utf-8?B?c3MzMGR1TTRQWEdXeW43eEJQYWV0cllSSEtIV3pLaEdyVlNUYWRxRDI0T0V3?= =?utf-8?B?Zm44aVBPWitCYWdadG5uMzZ0UGhJNWR6aDRDaU1CZTc4N3IvNnQ4MkFXVlI0?= =?utf-8?B?VzJqaENJdG1mNzJ6K0FpTWgxajNxZ09lcG4zcHdYUjViZlVqcVFqc3pGVWNC?= =?utf-8?B?cExYUlZFSVMwUXFjOXhqS1pFQmhpZGwrUEh6cWF3OFpqeEVMYko1ckZhbFAv?= =?utf-8?B?YjZidkR1VmJvbWVlMXhyRUVweGRMYjJJTjNDNEtPM1hCc3hodXZLb0tsNnBK?= =?utf-8?B?cktVTVpwNlZDVW4vbGVHamF4Z1F0bVkrVXBhRncydFQxSnRtaXJodXJnbWcr?= =?utf-8?B?NHZVeFBvS2ZNNU4waDdkaHlEbFJabkQ0b2hqZ1RvYUVuSHBtT0Y2OUdRQ3hp?= =?utf-8?B?cXhlNm1yM0tNc0FuQUJOenBVRHJ5N3JKNngxMWplVGxuS24yemZrUS9BTFVV?= =?utf-8?Q?y2il/Xi816vrZS92xT?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: ee147d69-69d4-4acc-2ef2-08df039170c1 X-MS-Exchange-CrossTenant-AuthSource: IA0PR12MB8374.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 26 Aug 2026 16:45:30.7829 (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: vt1qXxw0AyPtNXPhO7G2TZkvj/RaB09M84y0tN2xVqfFj8NGbaRXe/tB5SHgg55L X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR12MB7960 On Wed Aug 26, 2026 at 12:20 PM EDT, Kiryl Shutsemau wrote: > From: "Kiryl Shutsemau (Meta)" > > deferred_split_isolate() probes each queued folio with folio_try_get(). > folio_try_get() failure is treated as a lost race with folio_put(): clear > PG_partially_mapped, correct MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, take > the folio off the queue. > > The folio_put() race is the most common case for !folio_try_get(), but > it is not the only option. Another scenario is folio_ref_freeze(). > > A zero refcount in such cases does not mean the folio is going away. It > means "don't touch me" and current deferred_split_isolate() doesn't > respect it. It can lead to unqueueing folios from the deferred list for > no reason: > > CPU 0 CPU 1 > --------------------------- ------------------------------ > freeze a mapped folio deferred_split_scan() > folio_ref_freeze() folio_try_get() fails > folio_clear_partially_mapped() > NR_ANON_PARTIALLY_MAPPED-- > folio off the queue > give up, put it back > folio_ref_unfreeze() > > The folio is still partially mapped, but it is no longer a split candidat= e. > Nothing queues it again until part of it is unmapped once more. > > Skip the folio instead: whoever freezes the folio, owns it and owner is > responsible for its fate. It also covers the folio_put() case: > __folio_put() unqueues the folio via folio_unqueue_deferred_split(). > > Reported-by: Lance Yang > Link: https://lore.kernel.org/all/20260824131224.73344-1-lance.yang@linux= .dev/ Should this be Closes: ? > Assisted-by: Claude-Code:claude-opus-5 > Signed-off-by: Kiryl Shutsemau (Meta) > --- > mm/huge_memory.c | 19 ++++--------------- > 1 file changed, 4 insertions(+), 15 deletions(-) > Otherwise, LGTM. Reviewed-by: Zi Yan --=20 Best Regards, Yan, Zi