From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6078CC54E90 for ; Thu, 22 May 2025 10:05:04 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 037846B0082; Thu, 22 May 2025 06:05:04 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 00E836B0083; Thu, 22 May 2025 06:05:03 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E181B6B0085; Thu, 22 May 2025 06:05:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id BCFDE6B0082 for ; Thu, 22 May 2025 06:05:03 -0400 (EDT) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 5F26EC0E30 for ; Thu, 22 May 2025 10:05:03 +0000 (UTC) X-FDA: 83470110486.24.1784DA0 Received: from EUR02-VI1-obe.outbound.protection.outlook.com (mail-vi1eur02on2042.outbound.protection.outlook.com [40.107.241.42]) by imf17.hostedemail.com (Postfix) with ESMTP id 9A59E40003 for ; Thu, 22 May 2025 10:04:59 +0000 (UTC) Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=arm.com header.s=selector1 header.b="rVXvsg/a"; dkim=pass header.d=arm.com header.s=selector1 header.b="rVXvsg/a"; spf=pass (imf17.hostedemail.com: domain of Dev.Jain@arm.com designates 40.107.241.42 as permitted sender) smtp.mailfrom=Dev.Jain@arm.com; dmarc=pass (policy=none) header.from=arm.com; arc=pass ("microsoft.com:s=arcselector10001:i=2") ARC-Message-Signature: i=3; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1747908299; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=a+5SLwSUMxa+6cmExz9zYE8dag0PuseuiIrl7TIh/6s=; b=Tn/QcGfN/oJvmBGUdtUtZCUMvNOIbszbDLlwkyQmsjgFgUTEqcLG+meysmqeCXyn8xN16N 34lOs3CzQm4KoDAv6EId2EiDJPeUc70rsJpZPpAx+yVhUWFL+TK/9Y3L1PezrPoTObDoA8 so4DK38sA2bzQDIT5Wp92GL38jgir/k= ARC-Authentication-Results: i=3; imf17.hostedemail.com; dkim=pass header.d=arm.com header.s=selector1 header.b="rVXvsg/a"; dkim=pass header.d=arm.com header.s=selector1 header.b="rVXvsg/a"; spf=pass (imf17.hostedemail.com: domain of Dev.Jain@arm.com designates 40.107.241.42 as permitted sender) smtp.mailfrom=Dev.Jain@arm.com; dmarc=pass (policy=none) header.from=arm.com; arc=pass ("microsoft.com:s=arcselector10001:i=2") ARC-Seal: i=3; s=arc-20220608; d=hostedemail.com; t=1747908299; a=rsa-sha256; cv=pass; b=vQM8jhF1Ghi2jfZPADPFpT/DkZ2lB6iViyRP9WIegGq+saSmxE3SHD2BsTq6MN07JGo275 AIkABakqbhXjGytfcAwKdOjvz6zHdbvevl1rnyb2w6O97x6YWh2sRNirxBA1z2dL0L/7Om VDk58pFN0WIARoJEEIQTlhrX5+lqTPI= ARC-Seal: i=2; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=pass; b=GsyNTGyGWx+xksGmxfFwF9rcwyKThJt0KzbnXb25BxgEDOiT/H16DjNX7J1OTL9wJvekfAdKOfv6AivRRJnRjIroSavorxK3WWLmr5QCNjjUUS4DRkRzwvg2hBrhLsTkDFmlqPFn7uMH05vHVvaMoEPii8rPHFXYpPTEWh4u/rAE9A1SU3dKH66qV7bxpVCzpLTfRdAJT0ok+FOg4QWW/HsxHAb/HLemucZgUgyO+KKx/CWDHua/VzWEXiQQROAJU5ot0MaBVS8uX58MFDbQryK1TGYf1nWnp62UcF6ZQp0Vf3Vbvqew7cNQFLo1j9Scg2yuBZt/bjKkKLJHdJMyuQ== ARC-Message-Signature: i=2; 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=a+5SLwSUMxa+6cmExz9zYE8dag0PuseuiIrl7TIh/6s=; b=DthuXr6FbJXn1VDorhyVIUGn61tsVrCM66GxcdVr/Ve5VIgNZtycSu1dMyWPiDPzk/CWvtjQfODKUvJoTfXauujtZElpisFTBjl61XL1G91oHRQjjFfGqPc/m+FBV7GG4GxuRjaYDAhFg6N4NQO6NRkyoZwTNZm2AtVghmFrNcfcur3rh9mp5Xmsq9QHbqCQOdEjM9MJXH2Ai4WIFIbF5uzK41S4EkiZrJem9rvtoxj5Ey7KOr+IFJ0I1GB+s820mWqYD82kONOnBOiTGYii0+f383ceBSO1zwBFJJBYOcJD/W6bKt20N+7lTL3mtkZvAKv/NeTZlpEDnfjg/ACHDQ== ARC-Authentication-Results: i=2; mx.microsoft.com 1; spf=pass (sender ip is 4.158.2.129) smtp.rcpttodomain=linux.alibaba.com smtp.mailfrom=arm.com; dmarc=pass (p=none sp=none pct=100) action=none header.from=arm.com; dkim=pass (signature was verified) header.d=arm.com; arc=pass (0 oda=1 ltdi=1 spf=[1,1,smtp.mailfrom=arm.com] dkim=[1,1,header.d=arm.com] dmarc=[1,1,header.from=arm.com]) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arm.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=a+5SLwSUMxa+6cmExz9zYE8dag0PuseuiIrl7TIh/6s=; b=rVXvsg/awFjX0KPBEk1m7NvtV2OYB0A1ujtwyCdYcEWMlw6o+PU2TyiJaJ8zpyfpCk+28g7nnR4DLt2zeOoLauyZamRi8mVM4311sHOFfrwQ8hgoLX7MKiZs+TmuSJrUK5s5j6mx0/NYWsrQnskOPm6x1NeqMat+IGRzfqWK5rA= Received: from AM6P195CA0107.EURP195.PROD.OUTLOOK.COM (2603:10a6:209:86::48) by PR3PR08MB5723.eurprd08.prod.outlook.com (2603:10a6:102:89::21) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8769.21; Thu, 22 May 2025 10:04:54 +0000 Received: from AM3PEPF00009B9E.eurprd04.prod.outlook.com (2603:10a6:209:86:cafe::53) by AM6P195CA0107.outlook.office365.com (2603:10a6:209:86::48) with Microsoft SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.20.8746.29 via Frontend Transport; Thu, 22 May 2025 10:04:54 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 4.158.2.129) smtp.mailfrom=arm.com; dkim=pass (signature was verified) header.d=arm.com;dmarc=pass action=none header.from=arm.com; Received-SPF: Pass (protection.outlook.com: domain of arm.com designates 4.158.2.129 as permitted sender) receiver=protection.outlook.com; client-ip=4.158.2.129; helo=outbound-uk1.az.dlp.m.darktrace.com; pr=C Received: from outbound-uk1.az.dlp.m.darktrace.com (4.158.2.129) by AM3PEPF00009B9E.mail.protection.outlook.com (10.167.16.23) with Microsoft SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.20.8769.18 via Frontend Transport; Thu, 22 May 2025 10:04:54 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=HP9gQal3u6CmqA568Hk/vSGfEBWwLWWYWetlIy+VS5OVIzo6nlmoMHZCoyFJp+V3YeSfdQhhjeDwmqUjgPvyiozeR/RpyeR+Y8FuML4NSTnPN58qny9LGEn/bFF00T6T+UjxM5nhUHRGMslugBmLkuFBI5FUu/gZjoQGCEbQrbqd2vm2abm6h6QB8ECsiqBIipieu1yhwWXPPjw3GHsd7FF19UrFBAG5B08baX70n32R/l/3GyhPBKVssL+rmvaX6bX4kMm5dqwEfspM1Msivae/QkDEjZ9IAh9s7TLrIQnL3ufXtb5j8X4AvMIzAuZqVa/q5REpv09xa81/9n4RXQ== 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=a+5SLwSUMxa+6cmExz9zYE8dag0PuseuiIrl7TIh/6s=; b=CpWh6hpF7+mC6chJeexUmmz/aeIiibcxclLGC7dFM8x6CGnshoRYWLPPacbkGDBeyG9E0XYzUEdoaBZOMxtlM5b6n3yUrqEU+wXIze3Ddnc+3dNBxOVGVunTxJENu3R82qfzoSFtHFi/m+b7oZ2RtYfBIV25NJErYr1WtVzxO0hM8FCLbkQ0Dv9RYuWIw7GRbsubNwMMZfvvTepnkNrLv4FpN8/UNLvvA92JqlKKUO/UEufflVsHaSP2CLWC7CsyWk9w6MwY/J7faK0NWNyElaJyZQ9/fgMGOty+viQUtbj4clrzkaNPhvkSchepvfb0bnc1V3WITU2cmf6HgCvBHQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=arm.com; dmarc=pass action=none header.from=arm.com; dkim=pass header.d=arm.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arm.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=a+5SLwSUMxa+6cmExz9zYE8dag0PuseuiIrl7TIh/6s=; b=rVXvsg/awFjX0KPBEk1m7NvtV2OYB0A1ujtwyCdYcEWMlw6o+PU2TyiJaJ8zpyfpCk+28g7nnR4DLt2zeOoLauyZamRi8mVM4311sHOFfrwQ8hgoLX7MKiZs+TmuSJrUK5s5j6mx0/NYWsrQnskOPm6x1NeqMat+IGRzfqWK5rA= Authentication-Results-Original: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=arm.com; Received: from AM9PR08MB7120.eurprd08.prod.outlook.com (2603:10a6:20b:3dc::22) by AM9PR08MB6225.eurprd08.prod.outlook.com (2603:10a6:20b:2de::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8746.35; Thu, 22 May 2025 10:04:20 +0000 Received: from AM9PR08MB7120.eurprd08.prod.outlook.com ([fe80::2933:29aa:2693:d12e]) by AM9PR08MB7120.eurprd08.prod.outlook.com ([fe80::2933:29aa:2693:d12e%2]) with mapi id 15.20.8769.019; Thu, 22 May 2025 10:04:20 +0000 Message-ID: <1752d2ac-f346-44d9-aa2f-bdd8f046b446@arm.com> Date: Thu, 22 May 2025 15:34:14 +0530 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/khugepaged: Fix race with folio splitting in hpage_collapse_scan_file() To: Baolin Wang , Shivank Garg , akpm@linux-foundation.org, david@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: ziy@nvidia.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, fengwei.yin@intel.com, bharata@amd.com, syzbot+2b99589e33edbe9475ca@syzkaller.appspotmail.com References: <20250522093452.6379-1-shivankg@amd.com> <3eae6bb7-4865-44c2-8603-dc2bd8e3609b@linux.alibaba.com> Content-Language: en-US From: Dev Jain In-Reply-To: <3eae6bb7-4865-44c2-8603-dc2bd8e3609b@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: MA0PR01CA0012.INDPRD01.PROD.OUTLOOK.COM (2603:1096:a01:80::11) To AM9PR08MB7120.eurprd08.prod.outlook.com (2603:10a6:20b:3dc::22) MIME-Version: 1.0 X-MS-TrafficTypeDiagnostic: AM9PR08MB7120:EE_|AM9PR08MB6225:EE_|AM3PEPF00009B9E:EE_|PR3PR08MB5723:EE_ X-MS-Office365-Filtering-Correlation-Id: 378e4f66-b090-4ae2-a413-08dd99181987 x-checkrecipientrouted: true NoDisclaimer: true X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam-Untrusted: BCL:0;ARA:13230040|366016|1800799024|7416014|376014; X-Microsoft-Antispam-Message-Info-Original: =?utf-8?B?L2JjNzZDdm1RV3kyYkhYOHpQSDFWakg1R0ZsWUVmem51YTVXL0ltWVdLQ2lr?= =?utf-8?B?dmY1SUlRTFpCTW9pYTMwNXBWeXBIMFVnaVQxNjIrbmtKZVlYVWJneXg3M2hW?= =?utf-8?B?OEF1OXhjTGU5WlE5cDhOK0R2Mnlta2ZxV0laLzBGTFZpKytFU2tJeGlQRHFF?= =?utf-8?B?NmdnMUg5cW1pbTVtNHozUmhMS0pDYU13TWdlZFYreGQyMWZ2VVVpZE9tM0FS?= =?utf-8?B?S0h1TElYR2pFTlI5RkZHb1BEaDl1VkN2dkV3c3VLSWNDRm9NYzJqUkl0RlpE?= =?utf-8?B?SEVjVnkxZi9HU1pteW50OFJ6QUhWaFJySE13WURWdmlwam5tR0pHc1FvYUw3?= =?utf-8?B?SHIxSnlxMlA5N2lLVDNtR2R0S0JZd3E5QS9NOVovelUxVkxtRGFlV1VFSENF?= =?utf-8?B?d3FVT0pwUHplZ21pdlg0RTVpUXNaLy9JMVNqNVZqeGc3K1ErOEV4RDlYeTJE?= =?utf-8?B?U0E0SzZqKzBTSDU1Ukt5QytNVHE1NHZvODFRTjlZK0ZWZXRwVGNLZEFPeHJY?= =?utf-8?B?WjA3TG9kQlpaOXRYM1IweXJrM1ZZWkRYOWNGYjhBcnVsNkc0V092RlNDSHps?= =?utf-8?B?d0dCTlUweXZSZTM2QVpCQW82M3ZYaE1ocVdZUXRsTGZMczNhQjhsK3NFclpX?= =?utf-8?B?TTF1NXN2cy9IMExPRm4vSFNjaG5BZ0xhNVpDVkQ1UUdBWEdvaktMaExCamFR?= =?utf-8?B?V0ZTaGxXcWN3YnlJN2xpSFllMk0xd08ycWJUTXBWblZwNGw5QUpuRDBXU1hz?= =?utf-8?B?K1ZhMlVjbFpRaW9xV0JUT3FqYUIyZGNzcU1wbHpGczM0Tms0Nml5aUEwdUFY?= =?utf-8?B?emtFK0lhNmtDcDFBNkdqMnBqUzFWQ2ZBdDZHNlo5dytRbzRlRFJCTEJ4bFBU?= =?utf-8?B?dzQrdENIR3hoL1ZoeWFiTkROVU5vSE5ReEttNXUrTS80UkpPMG1qSExQYjZY?= =?utf-8?B?UlVURDJ5VmQ5VWYyT09JaVN5UjVzQ0I4d2pKNm1aR1M4bHhkUzNhc0ZUUGpx?= =?utf-8?B?SExJUERCWTRBOGxFaEg1RXlKRUw4YldtTWs0OTVhYjJUek1GMnlYUHhhUVA1?= =?utf-8?B?YTByOVBwZGpHRjdvUUhZRmM5eFpSdWlMWlJaYXhBcVBZS3BIMXhyVTNFR003?= =?utf-8?B?RUl4OW45SE5VWTlpcjMrVjhkdTZBZjZNZldzZStML0w2WXNtVDRYOUMwQkVS?= =?utf-8?B?TWh1VmJkeEQ2ajN2elI3WDdvVURpdEFjN1BBRm1zaVJBNUcrVi92NlltcDlq?= =?utf-8?B?bnFadk50OVh2Z2hkRzFMTjhweW4rUm9rdG1xTWRCYzZIcVZKS3l2SkZIQ1Q3?= =?utf-8?B?K3N2V05FMWlKWklkSWUzYUl1YmR5b3dzUmRQak5qUm9vY05xdTJ4bis3T1Ax?= =?utf-8?B?N1NPT0NLSjd6ZnN1c01MQzZ6RTYzZ1BsYWtVa014UmJyVzJQK2JEa1RVTDVo?= =?utf-8?B?U3JHTHQ5UHlzenEycExkNkpvWFZUenhQQlZ0ZW1FeUlUN1hiQmNwQXBTOGVj?= =?utf-8?B?L3c2d2Z0eEZhc3JONExXUkFFdjZQTFVZSHVXeG9NTldUcmtKY2tnVWNlQTRl?= =?utf-8?B?UjgyUzhwMmk5UGJWdWxpTGNSN29Pd3d3UFlEL0tGd2tMOXVaUW41SWtqdmJl?= =?utf-8?B?SHgxSEw0eTFoeVI3OC9lZTNubjZGNytrejRtSksyN2crMVV6ZGV3ZVdJZnNa?= =?utf-8?B?T0p4VjhGUDVmNHJOY2g4TnJDU1diQ3QrZGJRMkpmM3J1MU9sVm92NForN2FN?= =?utf-8?B?YmI2L1pmTHoxeTdOU0VYMW13YXl1R1psbEtBRGEzeWtuNzBvKzVXTlJuajFj?= =?utf-8?Q?8ttyIgC/i7LjQYT5bEl0VGuc9V5UiYlhwRcNE=3D?= X-Forefront-Antispam-Report-Untrusted: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:AM9PR08MB7120.eurprd08.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(366016)(1800799024)(7416014)(376014);DIR:OUT;SFP:1101; X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM9PR08MB6225 X-EOPAttributedMessage: 0 X-MS-Exchange-Transport-CrossTenantHeadersStripped: AM3PEPF00009B9E.eurprd04.prod.outlook.com X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id-Prvs: a66f6f92-14e4-4095-fddc-08dd99180511 X-Microsoft-Antispam: BCL:0;ARA:13230040|35042699022|36860700013|82310400026|1800799024|376014|14060799003|7416014; X-Microsoft-Antispam-Message-Info: =?utf-8?B?ZnBBUy9Rbk5rdFl5WjRvelhtdFh2dmtQQWJsd3hnQ3pHZFIrN0hRU0hnYzgx?= =?utf-8?B?czl6NndHeGo5L3FLYmFqTnpFWDJnNmhqZ3pSeFQxZzN6SzhUc3RZU21VeStw?= =?utf-8?B?WTJnQXlUOHNHd2JJSm04ZFplTlVNK3Zlbng5bmV5WUJSZ0loSmM3QlpkeTVZ?= =?utf-8?B?czVlTkJId25aa1Y4QXRFZ0d6Wmp6eUY1QzRTOEtiVXpUY0s5dlRnanY1bEJK?= =?utf-8?B?d1E1R0N0dHlnTXJUWGJXUmNwZVBEeUs0WDV5V2gvMmloektWZE9KcTI2VlFo?= =?utf-8?B?VlJPZ3YvRUhURnArMWgvcytEM1JveFZkc2Uxb1hoRkpPdytXYmwvSFVBYitK?= =?utf-8?B?RW80WTJLSUtJVDdtdEtXc3U4dzZWbDNrVzlTWWJtTlpQZ0I5VkpvZ0N2cENy?= =?utf-8?B?UFdBV2tDSU5NMk1sWjM2S24zZ1FJUWVKOWtaSW94d2x4SGNjekpiR2hHWXhj?= =?utf-8?B?K2tENUhoLzVnN091ZmRNbW1FVzY3RThBaXhuWWtHZ2JWQlR3ZHNRWnNTb2pm?= =?utf-8?B?c2F6c3BDcmU2cmx2ZVFkaXZsUExrY2xXQm9mZ0lhdEpLUWxQT0NyNGhHMzB1?= =?utf-8?B?QTYwK1AyZ0toVzhmUDE3YlRTVFpoTnNXckFhT1lQUmZnYXpGSXJYR0drMThG?= =?utf-8?B?aTJ5MnNWLzNPZW5rTStsdGZZTlFMNW9TWkRxQ1JYRUhRc1ZUeXFBZ2hWRzFn?= =?utf-8?B?MmxsK084M1hOTHRCd2dQYXUzQkdyUmxYejlzaWl5WFVKNkhSaHhHbkdZaURH?= =?utf-8?B?dHVoWkZOS3ovNnhvclNpR2NPdzFhbUdxczd1enVwYWJ4NXBiSDdxZzkvazZl?= =?utf-8?B?TVgvUkFqeEswVHNtMEdHMVU0UzN3NVJ2OHBOVndQVFlGUjBpb1NCbFRTWWlq?= =?utf-8?B?bHhjZEVUQ05FamxMTm9DNmtvYlVNNE1uM1hYR2RzelNGcHUwWE5La3NzaXhm?= =?utf-8?B?TVM2citrTnNuZlZZdUQxTlJPTXEvcndnRFRlNlVXVGpPK0hoS1ZVMzRBWWpL?= =?utf-8?B?bW84c1h2MHo5cnNaOWhKUk1UbFFCVlpsVElEV2Q2cGkrbCsrRk1VYk9CckYv?= =?utf-8?B?OWRobXZIOXp5eVZ5NG44a1NBUjZBVURackdoYk9MVnNId3p6bVEvY1Z3Rkta?= =?utf-8?B?U2Yyb0JraTZ5bWhRQUtWcVcyaVRwc2IzQUZNQVFFWWdGRzR5Y3l0TVE1N0k2?= =?utf-8?B?Yk5GUjBFb3dITFpqTFZmSS93dzFZTk8rUitseXhoV25jb09nQTdMVGJzWHBR?= =?utf-8?B?V0EvZS8vbVNyYjJpTkY5MUM5djlSN0RJV25NdDNRMEwyWjNPUWYwalAzcFpw?= =?utf-8?B?UC9FN0l0Q0ZyOWpTWU1GanB0Y3FhOHdXUkR5UDUzclJadGNIcHpxSmRaRHpX?= =?utf-8?B?VzA4NUNxcmM3REpmWkJPS3NXeFZxeGFJVmN5Z2RDcDlJdlFVVmJSS3MxWDRp?= =?utf-8?B?bzRYN3pBeVd1UEN6WWFnRW44ZjNuemtrckVTd2VLR015cWRsU0pxa0RDZE54?= =?utf-8?B?eVN4ZHhQVVhYVWJ4eDJoYXcxY1ZHQ2JVTm9SeXN1L2cwdFR6ZXNJTHlpU0tX?= =?utf-8?B?RlR4T3lIOWcvc0dpQzNiN2trelM1RDZtbC91UER3ZkxTOEhYYk1RWGo3S3Yr?= =?utf-8?B?ZTVwREVCSVlmaVlKT0dNU3VYMEJjcmFkdXhMV2ZGaHNWYy9uT3Z5T1J0aTVx?= =?utf-8?B?RGdOU3ZtbkFoWWJuQ2pySGdob2ZTbmZCRUEybmViSTBoTElVNVVreXBGOE05?= =?utf-8?B?Tm1XYkYrRS8xbG5pMzVNSUo3dUFlMkYyZXNXaitEaEdPZTRGZUtCcDFOYTI1?= =?utf-8?B?VkgvbkVLSWV0YVFZZW94eDEyaXM3d2JhQ3JUZVdBcUEwaWxDQTQ5OU81SEgv?= =?utf-8?B?dnNIazhVRXRKNU85Y2hjSWFUV1VmVndVQ2hQaXJJZXRER1Z2RGZtR0x1WjU3?= =?utf-8?B?RGgrclJzQ2doUWJ3ajBPMHpLcEx1K0QyQXY3L3VQVFc1SldwOWg5TFUvTkh5?= =?utf-8?B?N09uMkNaVkRBPT0=?= X-Forefront-Antispam-Report: CIP:4.158.2.129;CTRY:GB;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:outbound-uk1.az.dlp.m.darktrace.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(35042699022)(36860700013)(82310400026)(1800799024)(376014)(14060799003)(7416014);DIR:OUT;SFP:1101; X-OriginatorOrg: arm.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 May 2025 10:04:54.2192 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 378e4f66-b090-4ae2-a413-08dd99181987 X-MS-Exchange-CrossTenant-Id: f34e5979-57d9-4aaa-ad4d-b122a662184d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=f34e5979-57d9-4aaa-ad4d-b122a662184d;Ip=[4.158.2.129];Helo=[outbound-uk1.az.dlp.m.darktrace.com] X-MS-Exchange-CrossTenant-AuthSource: AM3PEPF00009B9E.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PR3PR08MB5723 X-Stat-Signature: 4hkt1gqxhmhkqdncr471m5fohwu3hdue X-Rspamd-Queue-Id: 9A59E40003 X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1747908299-655431 X-HE-Meta: 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 qJ+TPMA2 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 22/05/25 3:31 pm, Baolin Wang wrote: > > > On 2025/5/22 17:34, Shivank Garg wrote: >> folio_mapcount() checks folio_test_large() before proceeding to >> folio_large_mapcount(), but there exists a race window where a folio >> could be split between these checks which triggered the >> VM_WARN_ON_FOLIO(!folio_test_large(folio), folio) in >> folio_large_mapcount(). >> >> Take a temporary folio reference in hpage_collapse_scan_file() to >> prevent >> races with concurrent folio splitting/freeing. This prevent potential >> incorrect large folio detection. >> >> Reported-by: syzbot+2b99589e33edbe9475ca@syzkaller.appspotmail.com >> Closes: >> https://lore.kernel.org/all/6828470d.a70a0220.38f255.000c.GAE@google.com >> Fixes: 05c5323b2a34 ("mm: track mapcount of large folios in single >> value") >> Suggested-by: David Hildenbrand >> Signed-off-by: Shivank Garg >> --- >>   mm/khugepaged.c | 16 ++++++++++++++++ >>   1 file changed, 16 insertions(+) >> >> diff --git a/mm/khugepaged.c b/mm/khugepaged.c >> index cc945c6ab3bd..6e8902f9d88c 100644 >> --- a/mm/khugepaged.c >> +++ b/mm/khugepaged.c >> @@ -2295,6 +2295,17 @@ static int hpage_collapse_scan_file(struct >> mm_struct *mm, unsigned long addr, >>               continue; >>           } >>   +        if (!folio_try_get(folio)) { >> +            xas_reset(&xas); >> +            continue; >> +        } >> + >> +        if (unlikely(folio != xas_reload(&xas))) { >> +            folio_put(folio); >> +            xas_reset(&xas); >> +            continue; >> +        } >> + >>           if (folio_order(folio) == HPAGE_PMD_ORDER && >>               folio->index == start) { >>               /* Maybe PMD-mapped */ >> @@ -2305,23 +2316,27 @@ static int hpage_collapse_scan_file(struct >> mm_struct *mm, unsigned long addr, >>                * it's safe to skip LRU and refcount checks before >>                * returning. >>                */ >> +            folio_put(folio); >>               break; >>           } >>             node = folio_nid(folio); >>           if (hpage_collapse_scan_abort(node, cc)) { >>               result = SCAN_SCAN_ABORT; >> +            folio_put(folio); >>               break; >>           } >>           cc->node_load[node]++; >>             if (!folio_test_lru(folio)) { >>               result = SCAN_PAGE_LRU; >> +            folio_put(folio); >>               break; >>           } >>             if (!is_refcount_suitable(folio)) { > > You add a temporary refcnt for the folio, then the > is_refcount_suitable() will always fail, right? Oops, you are one minute faster :wink > >>               result = SCAN_PAGE_COUNT; >> +            folio_put(folio); >>               break; >>           } >>   @@ -2333,6 +2348,7 @@ static int hpage_collapse_scan_file(struct >> mm_struct *mm, unsigned long addr, >>            */ >>             present += folio_nr_pages(folio); >> +        folio_put(folio); >>             if (need_resched()) { >>               xas_pause(&xas); >