From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from MW6PR02CU001.outbound.protection.outlook.com (mail-westus2azon11012005.outbound.protection.outlook.com [52.101.48.5]) (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 97CC52EAB82; Tue, 30 Jun 2026 15:07:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.48.5 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782832029; cv=fail; b=oayGT9D1zFldwiRkN6EajjM7MDI/OkcsqpHWE+BuJ5h7nuSA+morIK+l0QpoKpEIebaqZFZmnnnEUs3KyYk4XZj/TaTlbyGsw8EP9EAbZRDQKVdbjq3sRfxl+bV/IN1K6FfDwsJOYScvtoj1EpE2WO3UCwgIAUNDE4JIw5kRKg8= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782832029; c=relaxed/simple; bh=M/Ab+Qs2laR4wA9jCNZFC1jX0p0hZf7WGz+XDWoQB44=; h=Content-Type:Date:Message-Id:From:Subject:Cc:To:References: In-Reply-To:MIME-Version; b=AeGqyQ6ZKS7DNMjz3fitTra/c16X1OTWc1nqHSU9ote5wEe4YwakoUsRBQYHFUMwhHkEpIAkAYtYoYnSKj++q8OXmjI3lhP2UrNWPmkLX+c3v+WpFTd5tFWdvsmmtcgJhFGy61Ui99ZQzqt+zd3+ODNMtOOEOu2App3F84uzUpY= 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=HKBE0lCL; arc=fail smtp.client-ip=52.101.48.5 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="HKBE0lCL" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=HMWQaJW91amOPk5ZRdWoUKADaNT5t7x4Mki2dI7UX5zCE2KDK49QGiLrLxt2Zo7JHYRPzqlv/PhpI5UzuZ2ARd67k72nxxFwl9JzMPCxVe1Cd42IxTlkL/cYMcFRzT+CA1k+fwlHx8yzacKa9OZpRd/9J+YeabDkbD91rz64mVCm/eJkWl3qKv4KTJnreYYXakFwX66n1qCp2iEX4ENQsNAeZ6dOCZiGixA2y9eLWUK7Z12FZBHtXIX0ts+dvkZzAdTkHRvLOqUscKX2ERVeAopWIJQU0/sQy1q4wHyMjocS0OoJ4WwdGVy9Gaj0IMQwrYScZjxHYhIsJGJ4xCvQ0A== 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=lLU8CqZnoAqMbfwvvS9pPYji7oGHjBeni2LaY9TVYbk=; b=RoCNHZjfmP2VscnRiFdyKysZYGfyCI+Fw5NY2LLKu3B5fjGqVvOpQesbiNlL4WEFBVn+YRXXz/zjDT5JxDblN2GEFazM3eK7sEXGPtdWu0NONmsO4a/jM60cixtQucO7qVw5PvzminpxE/n6KJ687ssCsZP4h0UGnNBvcwLKtfVJ6scJw8GU49bAPBlFDjSZb7UsfmT9wTVGnEaarbndEwgNE98J6QPnpsP6BTPelrTsb49tkgmWnJiP4ljAFvwXzatAiJiSZwwoaA7qzkSpDp4DvYXfc2u0cnCwaxIZxgfcNZt3TrxKPisORNPwpAsLQpwmTrSBn1iCINAtIcHt+w== 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=lLU8CqZnoAqMbfwvvS9pPYji7oGHjBeni2LaY9TVYbk=; b=HKBE0lCLJcOa3xlNhtehSnfK6l24U7EA3rbs/vwdPnVvfhzpCBAObWufu160IL+9VFZYDyz26FJgDJ3/aU4Gk7+wd6LE6QG5u4v/pNmk1bBHvFLRswgp/aEOnbztOdTupv2dGweBP07xV7X5+07vS67oAlppGE0lSlnacQ9rS7uBor9dbTNuYedzqYAhX6zg4IAUpH80F1LCKm9CQA2gekJsUdZ7t5o4DFlGxHe0phs7Yx7vDtU6/6v7pOe+gFYu2vzdeKytFlSYDzSweeNkd89yUUnZkPDtVJLn09vQFZA6JnXPsqZp850Vmp71mxwbp1NSo7V7OMbgbEjydxCLYg== 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 PH7PR12MB7258.namprd12.prod.outlook.com (2603:10b6:510:206::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.159.19; Tue, 30 Jun 2026 15:07:02 +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 15.21.0181.008; Tue, 30 Jun 2026 15:07:01 +0000 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Tue, 30 Jun 2026 11:06:58 -0400 Message-Id: From: "Zi Yan" Subject: Re: [PATCH] mm/page_alloc: free allocated PFNs if the range does not match Cc: , , To: "David Hildenbrand (Arm)" , "Vlastimil Babka (SUSE)" , "Andrew Morton" , "Suren Baghdasaryan" , "Michal Hocko" , "Brendan Jackman" , "Johannes Weiner" , "Lorenzo Stoakes" , "Liam R. Howlett" , "Mike Rapoport" , "Yu Zhao" X-Mailer: aerc 0.21.0 References: <20260629-free-pfn-on-alloc-contig-range-error-path-v1-1-496ff9ca22db@nvidia.com> <4549ad0e-abb1-4156-95c6-5e3c1319dffe@kernel.org> In-Reply-To: X-ClientProxiedBy: DS1PR04CA0001.namprd04.prod.outlook.com (2603:10b6:8:44f::8) 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_|PH7PR12MB7258:EE_ X-MS-Office365-Filtering-Correlation-Id: 87e3b50a-2fb2-481b-0603-08ded6b93ca2 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|1800799024|376014|23010399003|7416014|56012099006|22082099003|4143699003|11063799006|18002099003|6133799003|921020; 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)(1800799024)(376014)(23010399003)(7416014)(56012099006)(22082099003)(4143699003)(11063799006)(18002099003)(6133799003)(921020);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?b1RWeGU1ekVncUVoampTWlJqc2k0VDM5ZlVZNE9UQ0JVTHNVN2NvRWFQYzNS?= =?utf-8?B?cmQ2MkNKVldJZ2ZDdFdQQWFzamMrdEFzRFVnSjQ4TGlKWTFPSyt1aHZvc2ps?= =?utf-8?B?dnRUWW5LTjVSUlpsUWlxRVhVNFNNRUlNOXc5K0tTWFcySWVzMGZ3aU1lTDhy?= =?utf-8?B?SU95dTN4UktpODVpSkw4S21KVlhUSzlpeEpYRmhjN1JxTzE3dDNQdmtMNDNu?= =?utf-8?B?WG1KMzVzQ3g1dXAwSlBNR284Rjh1dzlQQ3pTTVNhWmdwa3JiVzY1M1FBYVFw?= =?utf-8?B?NXFQK25yV0J3M0ZpWTBFMzJFVHdXUTRCNld1dVJLMzFvUjArR1pwS3ZsOG02?= =?utf-8?B?QVZVN1RDTTBCcS94VTh6SVdGemRWVTh4Vm5jSnR6NStUaGRocXV5aTJ3RlJG?= =?utf-8?B?V25XbkJrY2VzT0pVSTlXTENXcmZqckZsRlJaeG9KMm1RdTZ2eUtQKy9VT0FB?= =?utf-8?B?SFExb3lXV1ZKK3Zva2JQSjAzazc2Vm9WM1BTN2tuUmxPQlgybjExU0cvSXoy?= =?utf-8?B?dU82UlZqZzVHMndzL1MvRHJoWGtPZnFrZU11WERPV3ppRUh6d1NTNUpLVGU4?= =?utf-8?B?bzhKS1FzY1NDVk5jeUQ0b2xoWmFuT1pOZmVoQ292ZG9lVEtyN3FUc0oySjht?= =?utf-8?B?QW4vQlpIbmhZU292SE1OaWdqT2xXeHIwa1h2bUF6Mmo0ZXUxUlRFbm0vY05I?= =?utf-8?B?ZmpTbnZmS2tucmhBUUtUUXJGQVRzS3FXaXVZcjRxdUFEUGlJRVFkejRuajdH?= =?utf-8?B?Q1YyelN0NXlVOGhId2JObkYweXJyREJGYUwvWDZuNCtLRFpHOGYyZkVXQlNV?= =?utf-8?B?eERYRE9YSUYzcFNyeU1xRU9SUzREdHdKT0dDaVIyZlRWaWFwaytIUktsS2tP?= =?utf-8?B?NzZKdVRBbkJRY3l1MkFDWDMyRTdSUW9QL2lycUZvWm1GQ1JpeTRHYkY3dnFn?= =?utf-8?B?MWtvS0h5SjRCc2QxVXZVNWpaaDhNUkFuYzNsc3k1UzR3ek5TZHRYSGkvSVkr?= =?utf-8?B?c2EyZXlOeWQ0ek9HMGt1QzUxTlBQNUtMbno4am9lVCs3a1dmeW1HVnBHNW00?= =?utf-8?B?QjhzM3FocW9jSXdpMmtLaUFiWC9WTDlUb3dMQnM4MVUxZTNLSGxvM3FrcE5B?= =?utf-8?B?RUN1dVY1dHBheXltTTdWTWk1bUJ4VUFtZnl0NkpZbWFIb1R4U2R3NFhTWU44?= =?utf-8?B?NVh2czcvRmdZa2NxamZWWUVSRFMwdjBreG95RnREemNaOXZ4L3pjSlpua3RC?= =?utf-8?B?YjlRemxxNGZiaENZa1g0OFFPRVBoNk5vMGFHZzk0MHRJV1F5T1RKMERrR0V1?= =?utf-8?B?dGY3a2F3M2syNktEeUFNSDUxZ2czNERrQ2ZsUklQR2VqTDNrSmVlaWdSalph?= =?utf-8?B?bnBrWVlkQjZkN3NjeUFSRDUrVHZPNFZRd1dZKzNmcDJTMmVBTUZhV1ZYN0tv?= =?utf-8?B?Y1loSGlUV2tVcE1XS3NrTnRiSXpTdUxpUCs4U1QwSTQ1ZDdvd1d6U3A0SHNX?= =?utf-8?B?Z2hkcWt4aE0vRk0vZlhERlV5SzJ1MkNHTVRZTDdQd0V0aHVFeGFkVVhGeitz?= =?utf-8?B?WElTSElwRkplNWppR2c5Si9YeUEzdGVkYUlDdDA1eVZZc2lkK2tGbkZNVXB6?= =?utf-8?B?dExyR0dtdmVXTTZJOWljR0ZKN2J3ZitjaUxtaDRSNzhqZk9idnppWXpPOTEy?= =?utf-8?B?aG1YdWRoaTNiQmJuRFA3NnJBYlZJTnJKZ3ZJQ1ZKQVlrQnRaRVBRbmJ6OVpO?= =?utf-8?B?NTJkTjMwT3I1aXRwc3FwcU5uZ3lyUzVQSmJaV1pQamY4dUQ2aVZlc05wODZq?= =?utf-8?B?aVdFQW15M056a0ZrbXhLbW53Ulh1aE15S09PTUg2U1p1NVM5d0ZlYlpIcm9L?= =?utf-8?B?eDZhS1FFZjc0c2NnVXBXYjE0SUZ3L1lxdTQxeFVpdGJ3ZTFRMldTa1FBUlZv?= =?utf-8?B?VmZnRzNKTzVzY0x1OXFlOTd1SFJSb0ZINWQ5YjlRVlVTRWZwbWhOVW5sb2tr?= =?utf-8?B?RmJOVjB6T20vTlRydTNDVWh6czE0aHBNdW4yalIwc2xEa1JBMHVtcFNkVHYy?= =?utf-8?B?ajZUUzRuWWRnZGF5U0xFem0zTmxwVnJXT3FDQ08yc0l1K2FZZlo2MzFDTENj?= =?utf-8?B?cjBYUksrUlc3RklPY2pJczI5K0V0VWlMcUY5ck04b2xrZkcycW0vcUd0T0E1?= =?utf-8?B?bi9QUWlqOVJ2R1pOMm9Ed2NlODJqekFrQWhnTUFMZWI5Z0c5N3pia3B1eVpT?= =?utf-8?B?SW5Xdmtnc0t3UjRZZ1NoYW9sWEJvejdxN2piRnV3bWQ3TGU0aDJVdGdscno4?= =?utf-8?Q?N9Q5umO/bfHnivaImc?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 87e3b50a-2fb2-481b-0603-08ded6b93ca2 X-MS-Exchange-CrossTenant-AuthSource: IA0PR12MB8374.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 Jun 2026 15:07:00.9581 (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: TehMUaloaw814Tdz2H2rbSi8gwpbV8vGT5abEPaH5GLGItFUGh/0Lm63AWo3Dzh6 X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR12MB7258 On Tue Jun 30, 2026 at 9:39 AM EDT, David Hildenbrand (Arm) wrote: > On 6/30/26 09:44, Vlastimil Babka (SUSE) wrote: >> On 6/30/26 03:35, Zi Yan wrote: >>> When using __GFP_COMP in alloc_contig_frozen_range(), if the allocated >>> range does not match the requested one, the code errors out with EINVAL >>> without freeing the allocated PFNs and causes free page leaks. Fix it b= y >>> calling release_free_list() in the error path. >>> >>> The issue is reported by Sashiko[1]. >>=20 >> So this? >> Reported-by: Sashiko >>=20 >>> Fixes: e98337d11bbd ("mm/contig_alloc: support __GFP_COMP") >>> Link: https://sashiko.dev/#/patchset/20260628-keep-subpage-private-zero= -at-free-v1-0-f4ce3930d10f@nvidia.com [1] >>> Signed-off-by: Zi Yan >>> Cc: stable@vger.kernel.org >>=20 >> Hm well, it's a path that warns, can only happen due to a development er= ror? >> Not sure we care about stable then. Anyway. >>=20 > > If someone would run into the WARN we would already be in Fixes: territor= y. > > it's a path that should never be executed. If it does, the real issue mus= t be fixed. > > So (a) I don't think this is stable material (b) I am skeptical that this= is > even a Fixes and (c) I am wondering whether we should touch this *at all*= . > > :) I looked at the code again and agree with you that the code is not reachable and the fix should not be in the WARN path. Theoretically, if order =3D ilog2(end - start) is smaller than MAX_PAGE_ORDER, find_large_buddy() can return an outer_start smaller than start, leading to this WARN path. But currently alloc_contig_frozen_range() with __GFP_COMP is used by gigantic hugetlb, thus that is not possible. How about 1. making sure order is bigger or equal to MAX_PAGE_ORDER, 2. adding a comment in the WARN path to prevent someone else trying to fix WARN path if Sashiko reports this again like the patch below? diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ee902a468c2f..e87d3fced9d4 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -7130,8 +7130,13 @@ int alloc_contig_frozen_range_noprof(unsigned long s= tart, unsigned long end, * In contrast to the buddy, we allow for orders here that exceed * MAX_PAGE_ORDER, so we must manually make sure that we are not * exceeding the maximum folio order. + * + * The order cannot be smaller than MAX_PAGE_ORDER either to prevent a + * potential mismatch between the requested range and the allocated + * range that leads to an allocation failure. */ - if (WARN_ON_ONCE((gfp_mask & __GFP_COMP) && order > MAX_FOLIO_ORDER)) + if (WARN_ON_ONCE((gfp_mask & __GFP_COMP) && + (order > MAX_FOLIO_ORDER || order < MAX_PAGE_ORDER)) return -EINVAL; =20 gfp_mask =3D current_gfp_context(gfp_mask); @@ -7235,6 +7240,7 @@ int alloc_contig_frozen_range_noprof(unsigned long st= art, unsigned long end, check_new_pages(head, order); prep_new_page(head, order, gfp_mask, 0); } else { + /* Fix the caller if this is reachable */ ret =3D -EINVAL; WARN(true, "PFN range: requested [%lu, %lu), allocated [%lu, %lu)\n", start, end, outer_start, outer_end); --=20 Best Regards, Yan, Zi