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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 20D1DCCD183 for ; Thu, 16 Oct 2025 08:34:44 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 533DB8E000A; Thu, 16 Oct 2025 04:34:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 50B658E0002; Thu, 16 Oct 2025 04:34:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 384F28E000A; Thu, 16 Oct 2025 04:34:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 224B08E0002 for ; Thu, 16 Oct 2025 04:34:44 -0400 (EDT) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id DEDDD11916C for ; Thu, 16 Oct 2025 08:34:43 +0000 (UTC) X-FDA: 84003316446.14.1FF1E6F Received: from mx0b-00069f02.pphosted.com (mx0b-00069f02.pphosted.com [205.220.177.32]) by imf10.hostedemail.com (Postfix) with ESMTP id 77473C0006 for ; Thu, 16 Oct 2025 08:34:40 +0000 (UTC) Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=oracle.com header.s=corp-2025-04-25 header.b="hyR1/O2U"; dkim=pass header.d=oracle.onmicrosoft.com header.s=selector2-oracle-onmicrosoft-com header.b=yt+HF7IL; spf=pass (imf10.hostedemail.com: domain of lorenzo.stoakes@oracle.com designates 205.220.177.32 as permitted sender) smtp.mailfrom=lorenzo.stoakes@oracle.com; dmarc=pass (policy=reject) header.from=oracle.com; arc=pass ("microsoft.com:s=arcselector10001:i=1") ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1760603680; 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=0/sd88coQ6lgIZsVSAWGs93BgI0y/tbo5viUxeeuwM0=; b=QIEmZQO1ivVhqpu/nSGgnXHpCuI8rvxZm/+cyCHxfrxktfnwm71mqWZZrKpZmHzElPjzIu UkOnepGzdpvgNFkgvY0890WW+28IoJKULI9PLDZN7pkGAnyXRz3Upldp7BRFeG6hBq7tfO Pg3uKWPDgE6CSDeRN0OKxEVwLgKp6QU= ARC-Authentication-Results: i=2; imf10.hostedemail.com; dkim=pass header.d=oracle.com header.s=corp-2025-04-25 header.b="hyR1/O2U"; dkim=pass header.d=oracle.onmicrosoft.com header.s=selector2-oracle-onmicrosoft-com header.b=yt+HF7IL; spf=pass (imf10.hostedemail.com: domain of lorenzo.stoakes@oracle.com designates 205.220.177.32 as permitted sender) smtp.mailfrom=lorenzo.stoakes@oracle.com; dmarc=pass (policy=reject) header.from=oracle.com; arc=pass ("microsoft.com:s=arcselector10001:i=1") ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1760603680; a=rsa-sha256; cv=pass; b=19o6+JPBojHoN0GdcwGrNStP8414D+WAYTi6gruHAGCaTLx1QAEFPgZ96IlZ0rvV7aPMLN t0HnsbHqFj1MDIxapQ3Cuj3u12dDmdMydjHCmO9szMf5u9ZgTdqbJ0cAJ52usLEXgzEDCl TvQejGQO1RqnsV9SCka9UnVoD0BadhU= Received: from pps.filterd (m0246630.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 59G6gxer010695; Thu, 16 Oct 2025 08:34:27 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s= corp-2025-04-25; bh=0/sd88coQ6lgIZsVSAWGs93BgI0y/tbo5viUxeeuwM0=; b= hyR1/O2UwMkdl0bsm1bbwerhWYqherzSrM+ePT0VGQRG4Nr3GsSx1eHu+rJfU2FZ RNC7oDcRpX2Oqq+J3AJz3bTqeGAOwQ5g/WsOLBFlce7/KAvsWhEUa17NRORVVdC5 Y07FHMk2B+HeicFdomWBSPALCQVN52NDMci4caD2kcg8N/DVd4mvzQawwLy+jnOn xOCeNBxHHtegK5/xgKU80C/3zOKcWWuojcW7SHePMiQul06QW2x020ETD/eKqCKp ps0WzPXgQ/XtJfUFlMCoTFTjIbgFUL/HTIfZPXfApOQwd8w4NighPKkjF7LWbqen lzCt4qAvHyyGD1s2tBtH4w== Received: from phxpaimrmta03.imrmtpd1.prodappphxaev1.oraclevcn.com (phxpaimrmta03.appoci.oracle.com [138.1.37.129]) by mx0b-00069f02.pphosted.com (PPS) with ESMTPS id 49qdnc8csy-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 16 Oct 2025 08:34:26 +0000 (GMT) Received: from pps.filterd (phxpaimrmta03.imrmtpd1.prodappphxaev1.oraclevcn.com [127.0.0.1]) by phxpaimrmta03.imrmtpd1.prodappphxaev1.oraclevcn.com (8.18.1.2/8.18.1.2) with ESMTP id 59G7mvsJ018074; Thu, 16 Oct 2025 08:34:25 GMT Received: from ph0pr06cu001.outbound.protection.outlook.com (mail-westus3azon11011028.outbound.protection.outlook.com [40.107.208.28]) by phxpaimrmta03.imrmtpd1.prodappphxaev1.oraclevcn.com (PPS) with ESMTPS id 49qdpbd7fq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 16 Oct 2025 08:34:25 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=Do2BHFg9Sgq09CtPHUasHk14U4vBjNzpGAQaz6oawAOiq1nXvirZpjnlzdIN2BJB0gIxZfmrIUysEI4LgjKxLQo7u5DzpdUHMTdvnE7gA92WDrZ6NiOTotS6K1Xz4EEs9Ajd+RO4H4MV6t0A8s7x8cB/ghunsdUR8zY1VWSOqu4MHl2uqRHnl/n27o5Lh6ilKNnTu3cIlYo77cJakRyKwpndsUDp9Lt7D4Vrm1OYQxhHuyHCHa/0gMg8wbhGlnNjqi/W8uexGfLkh5IgkgUYwh5gzUfe3RBNU58mWRrSHCH9q7ip07RInUkYFsSTsxqY/X4PgszgzUT7FivZe/tgfg== 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=0/sd88coQ6lgIZsVSAWGs93BgI0y/tbo5viUxeeuwM0=; b=fFI7EIIkAIMfJDT9Cp4/A6l3aMCXtfkIa8jFCAPtbbHhfhTLg4E2LLi48yirK0B0bqdaq+mUdZZcCVqaZJ2ZFPiTUZXmTX6VlELthHUEFb0n/Kcl796QA+/Dhd6BVHkyk0LUovPwoQDPmBs3zy1rLGTC0wgLYGwql08DGt++XVKO0EkBTpjUnwY++VpUs2oHTrhqvMK34rYOxcJpBTOth1thBUlkQptvpm5R7n2UK7QklzIISb3Kq4bZVbltCk547BVXRr73AvBzrfYK8kf/hsnUA/uDHFW1DHIWJgfPNk6dQ88hvXG7aMj3SwbQgFrq/h4KAdV3G+IPsFz5VmQpCQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=oracle.com; dmarc=pass action=none header.from=oracle.com; dkim=pass header.d=oracle.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.onmicrosoft.com; s=selector2-oracle-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=0/sd88coQ6lgIZsVSAWGs93BgI0y/tbo5viUxeeuwM0=; b=yt+HF7ILaQJwYfxfBmnQC/w+xzsqbAxE3ZJ6faJGpNVGv+PRG9jyuvS/U2cBJLIUvPsBGiI6f1dNveIqB6y8YtogqJsjQnnnC8czHCKgFMQ6NM5MNr1C5ZNoFeww4LCTgOlNguHrLrjAyd5ppt50eHBv00OQrYsJcIlz9alEHyA= Received: from DM4PR10MB8218.namprd10.prod.outlook.com (2603:10b6:8:1cc::16) by SA3PR10MB6949.namprd10.prod.outlook.com (2603:10b6:806:319::19) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9228.10; Thu, 16 Oct 2025 08:34:18 +0000 Received: from DM4PR10MB8218.namprd10.prod.outlook.com ([fe80::2650:55cf:2816:5f2]) by DM4PR10MB8218.namprd10.prod.outlook.com ([fe80::2650:55cf:2816:5f2%2]) with mapi id 15.20.9228.010; Thu, 16 Oct 2025 08:34:18 +0000 Date: Thu, 16 Oct 2025 09:34:16 +0100 From: Lorenzo Stoakes To: Zi Yan Cc: linmiaohe@huawei.com, david@redhat.com, jane.chu@oracle.com, kernel@pankajraghav.com, syzbot+e6367ea2fdab6ed46056@syzkaller.appspotmail.com, syzkaller-bugs@googlegroups.com, akpm@linux-foundation.org, mcgrof@kernel.org, nao.horiguchi@gmail.com, Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , "Matthew Wilcox (Oracle)" , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 1/2] mm/huge_memory: do not change split_huge_page*() target order silently. Message-ID: <350b69d3-0680-41c9-8b3e-578504894372@lucifer.local> References: <20251010173906.3128789-1-ziy@nvidia.com> <20251010173906.3128789-2-ziy@nvidia.com> <9F4FC13E-E353-4A4F-BEB7-767CF4164854@nvidia.com> Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <9F4FC13E-E353-4A4F-BEB7-767CF4164854@nvidia.com> X-ClientProxiedBy: LO4P123CA0225.GBRP123.PROD.OUTLOOK.COM (2603:10a6:600:1a6::14) To DM4PR10MB8218.namprd10.prod.outlook.com (2603:10b6:8:1cc::16) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DM4PR10MB8218:EE_|SA3PR10MB6949:EE_ X-MS-Office365-Filtering-Correlation-Id: 74fe22e7-1ae9-444a-0326-08de0c8ecc27 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|7416014|376014|366016|7053199007; X-Microsoft-Antispam-Message-Info: =?utf-8?B?b09LSThXZ1J1U28zdUJiKy9LY3BhZUFERmMzQmZMcFBFaWptclZCdDYxZGp3?= =?utf-8?B?akN3V011MmdHMnBRMFFKcHZVT09pTFY2dWhyZUtENTRGdHNWS1VtSkVQUUwx?= =?utf-8?B?LzB0YWR6eHR3K2VkSlJTVnU3aXNQL2p5NVozNVhiTEI4NWpML1dRTEJYbk9Q?= =?utf-8?B?cU1qN3dCQTQ1bE5lQVMxNDkrNC9TY3o4bGFHVUlrTmM5clQ1TVV2dmJ2Q2tj?= =?utf-8?B?Qnc3cmp3UW0yZ0FpMWpWYmdqVUhEcnlUZjBPZVlzbDlCLzVUOWxlZHB2QnhN?= =?utf-8?B?dFNXRklFSlFvM2EyWnBaVWdSc2F2dFRMdzVUMFllVkJjRW9sUXJPaUNib01v?= =?utf-8?B?b3IvN1QrL2d1Q2Z2aExkWi9mL3pkQVErZ09Wb2hrWmVzQTR3cjZXdmpWTFR3?= =?utf-8?B?VWRzSkNrYmVmQURxSms2a05VMnZ5SkVPUGc4eVJJSTZWTVUwWUMzVktEaUVY?= =?utf-8?B?QjErUS82WW5Qd3R6R21tTmd3RUUzQlk5VHI2a1lhbncwMk9YR3M1dVlMUDUz?= =?utf-8?B?KzBYOEpmdm5COC9janVuOVVVWTNDTTdQUUN2TldZak9walNKV2YvOFoxWkNO?= =?utf-8?B?OHhNayt0YWJoN25ldXdhb1dPbGNZUTl5OFc5cjBFWjEvemZNTXRjb0xYL1ZZ?= =?utf-8?B?bFZ5Umtnd052NzMrbm5xMlJYOUMxL0liT0lrTVRwR2NwZktYU0lIcE02Y2ZE?= =?utf-8?B?WHlJOFAvbVd0ejBHNkwxS2loc3VlbWJaYVRMOW5lc3dvSFF5NDFUQUd4UEp2?= =?utf-8?B?M2hQMVVleDBlL1hvQjVFRnBLeUJ1ZVB2ZWNGcFpXcThQenU5eVkyYUZPL2RL?= =?utf-8?B?aGdGRk44Y2Zjd0tqOEhUZGtVbnVhQ3FzTk9mNGVRUGRUbEtMTXdaWEh0a0l6?= =?utf-8?B?aGhaYUZGZ0FMa0krSVFQL1BWaDBxekJJOGI4ak9QeGF5c3ZLc25YSFJDckVm?= =?utf-8?B?UFZYWVZnaXBaZml5UzNsV2ZjSzJ0SW5wV1NpUVJKNlcwR1dkUWtTVkhhekdm?= =?utf-8?B?VCtGRFlxVzViSmhYMkZSOHc1ZE9WN3VzdU1IUG12V2Z5TVNndjdqbVo1L25k?= =?utf-8?B?a2x2WXRXVXVZSUk4c0pTTDhmK2duYTNCUEdlS0tVS21QcFhvVFY4RU81b2hU?= =?utf-8?B?SFRlYjZaNUhscHBxR3ZCV3FRdVI3bWcvNmpESm43MW5YOVNJRXVzUnJHUGIz?= =?utf-8?B?dGx0cWhkUXhIS1NvSHJMSGVYcGI3TXdKT2k3TGtwT0MzMXhjV3RscS90dHFK?= =?utf-8?B?eklJWUVBbnE5Q290ZU0zcXR5WldCMitKaUk1S3ptTktLQ0w5bWo2RUl1U1d2?= =?utf-8?B?Tk5LU1cwOXdtUzlLOWs2UzkvTUdKdGVnRnlBZ2xNK3hSM1lab2V3dDYxNlhK?= =?utf-8?B?ODRJY1U5WjRtWHdLbjFIdWV4UFJqMjcwQUR4RGR5MzZHYnlmWnM2bG1tcnNp?= =?utf-8?B?Umk1QTdlQmRjWGxrbFN4c01JTExockZKZHBBY1ZLZXBrUnVyLzRRTEpyV3RQ?= =?utf-8?B?QThUNVFBS1VOakJVZXhiSjhGWFE4azh3R25tTmVTMmp2ekd0eDdWQUVGRlRr?= =?utf-8?B?UDJZZzVGQU5XWmVIMEFBd1hRcXprZ2RWSEx3U3p0Y21iZDZHR0dDUzFJYVZr?= =?utf-8?B?UjdmV0l3blBvWEd1Ty9IYU9JMmRDcVpNN2lWWlpPOXpwSWF5cHllNjRRYWwr?= =?utf-8?B?T1VVQWhicDIyOUprbjlXMFpsNFJTOUFxUC9uVXFLaGZwRXlxOFlrZWFIa3ZD?= =?utf-8?B?bXBaV3pNZ3JnaWM2MUVrc0pDcWQ2TktoZnhGWmZibkIvMEptQTZUTnN3UktB?= =?utf-8?B?NWVaR2hYK1FvY0F1TzRqODBNaTF4TktGaGFQZCtBVko1WklOY0Nuakt4OUlx?= =?utf-8?B?cUpiYnBkcitWbWZJUkFUMFk0Q003OWgrUzFZWng5NDV1SWc9PQ==?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DM4PR10MB8218.namprd10.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(7416014)(376014)(366016)(7053199007);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?aVVPUmtkdVN0WTVRUGw3N25OTzBFU053eG1ZQjcrU2pyUEkrM1BEcDRSZnk4?= =?utf-8?B?OFl5VTM4MmQ5cHpvYVBVUkhrUUgrMW9wSW9OZjlZSkJjbUJjUnVJRE1oNTRw?= =?utf-8?B?OHhTMWptbWRKR0JZak5UNW1LWDlTNVB1OTBKZnE1VTN1Q0FGTmcxbEh0WVRC?= =?utf-8?B?SmhrS2RHVjJpV2o0RXRHK0NQa1hUYmR3R3dRTzZvWXg3U2FlV3g2YXFDUFNS?= =?utf-8?B?RjZlZ1ZWLzZoN2VzODQrOWk1UkFPY04ySE5FNnE2S2MzWkFuc21TcVJuTjM3?= =?utf-8?B?UytxaU95QURCdHRQR3dpNEN5T05PUmpqcnE0a2xVNHptWFg2bDd3K2hIOEdy?= =?utf-8?B?R25HdDk5VlAzS2RMaStuVFVDcHF6NHIzYmFGNlFtbndHOGM2TzZxL01SR3Nz?= =?utf-8?B?R0RpeUp5N0l6NERRTlB3N1JzUnN1ZldndG96RFpNcC9aQ3NCZGROOWQyNlJV?= =?utf-8?B?T0xsa3NzQm0xbXZaZkk0clNtK0dkWXVMOTdMeVN2bEIwRmZSVnp2aThQeTlC?= =?utf-8?B?MHR5cW9FcDFoOHAyRHVHV2pUTms0cnVuVGpnc3VQN0VGQ2g2NExkMDhPQTRt?= =?utf-8?B?T2RkRzE3K0pNSFJCR05rRlVsaW5rZ0pKYU5QMmZ6WnhNK0U1Q3AxN3Q3N2h0?= =?utf-8?B?VTNibnFwWkxvdERUTEZVeEwraXRMdTNnZ2ZSZEtzd3QyaEFQL096OEV0em9L?= =?utf-8?B?MkxhSmtvVnJUY0JRT1FwZk5WUTl1K1dsUkFFU21WdkcxcnY1aHJlYTFsZ0ox?= =?utf-8?B?T2tGTFIvOHRVZ3pxVVZmOEt2TzFleC84ei9zL3RQck94cFNnNnFhb2Ywdjgv?= =?utf-8?B?NXBUNDV2RDd4Z2Z4WUs4SnpTQWRKNDU3djRDOXhkdW9rajR4QVVjakJjZkFp?= =?utf-8?B?aE44VHA4c2REM2xIWXBTYk5VSk1YWTQvZ281Q0xhd2V5QnJocHEvVFJMbGtk?= =?utf-8?B?RmZ0cC9OZjF1YkszUnNtbFd2RTcxK0x6UzNvZGZHVFZkbTN6MVJxSkNXU3Bk?= =?utf-8?B?OXhUdzF3TlNuTnIrcU1lTnQzeG9pc0ZlNmZjaGhxc0lZWXEzakd1U2JVazE5?= =?utf-8?B?eFh5bUVQdEhWQ0xZQi9NVy9EWHQvMTRwemlacnJ2M0dzTGpaTjM1eDhxT0NQ?= =?utf-8?B?WFR1RlE2cXU0UjRBclltdnRyZzRGMWhSZHFJU2xIa3lGMjNjNzUwMm1VajBF?= =?utf-8?B?OG52d2JNb016SDZMN2Z6TFQxTXB0aWVBRnRsWFZXeFVSM0wrVnIrejJkUEls?= =?utf-8?B?b1JwOS80RzhZY1NOa0I1ZTJKbmZsaDB1ZDYraFlwSW9TSXQyN0hPcFVxZ0g3?= =?utf-8?B?b05RN3ByVVFtN2dLVGZJM2s1MXBNQ2dWcWxUVFZWeUEvOS92ZFhWS1dqd200?= =?utf-8?B?U3BaQjQwS1RvVy95amFyVStZS1BxZ21Ia3lGQUF3cFh1VnltVFZqRjdhSFpt?= =?utf-8?B?SHZETjRJMEpxallWRHFpWm9IRFBudnpJb1I0L0RaWGdwbEQrU0xzTHpQTU9r?= =?utf-8?B?ZlF1a2dNbm5nSWdFMXJCNngrT1ZPS0dMN1pmZE9NYnNPd09XR0tuY3ZrM2wy?= =?utf-8?B?MEpxQ3IvYUJ2ZjhrN2t0NitwRlpRUThEOWVhWVVWUU1lRkRncWtDRWFmOGNq?= =?utf-8?B?Ry9MbHpmc1pCSGk1ZTh4ei9lMEJ0dHJHdUNmV3lWUFo4dUthVGE5VUxDSWFL?= =?utf-8?B?NXJsdWw3b0toQTR4ai83MTZXWkJZM1RRcnpPd3h3VjhkWEw2WDdLbjJUZ1F6?= =?utf-8?B?UWNpSmNtZmVNMFZGNURZUGVnZjdDb3FjNEFsRFFRUDRKZ0RqWHp6VzRtLzM5?= =?utf-8?B?SDBwWGlMRVNlZlZiTmFNS3hxUXRZL0FUWEtiU1FhOG5tTDAzekluNE9FclM3?= =?utf-8?B?TnNyY3d2dE9SYjRlb3dHRGJmSDl6K0dWZlFvTGE3L2Z4Si9lTEVha2tJQXk3?= =?utf-8?B?WTZEWnBjRlJlM2s2VVlsdklyWE8wV0FPbGc1ZWJ1NTVkdmxZN3YwSWwybThh?= =?utf-8?B?ZmkrWE5zOVFMNnA3RERIRkI5WlZPVTRpUGY1MDE4ek00MnhQWWZGNDZQUjl1?= =?utf-8?B?ejBmZ0JidVZndE13ZGM1a2t2cmsyWHlZVXUzZGovNzZzNU9ZdE1tNHo2c2RF?= =?utf-8?B?YnZ5bU44Si9BSGE4UWtVNlkvZndWTmhVQU5aVDY5ZlpEaHQ3WGxHRlJQb3lM?= =?utf-8?B?a0E9PQ==?= X-MS-Exchange-AntiSpam-ExternalHop-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-ExternalHop-MessageData-0: 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 X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-Network-Message-Id: 74fe22e7-1ae9-444a-0326-08de0c8ecc27 X-MS-Exchange-CrossTenant-AuthSource: DM4PR10MB8218.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Oct 2025 08:34:18.3865 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: i+Z1J8utVXn/w/T1A0pALEWEWj+9AnXbvRILit/Fu+myLb2qiFOqfo7X6R9l0Cz/6Fha0m+hsf4QBi0KRFwpvbddEH9af4GzjYiyaAF6E1I= X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA3PR10MB6949 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-10-16_01,2025-10-13_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 phishscore=0 mlxscore=0 suspectscore=0 spamscore=0 mlxlogscore=999 malwarescore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2510020000 definitions=main-2510160066 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMDExMDAwNiBTYWx0ZWRfX9+2fArU5ka01 VgRngPNnIiUHDvNpqBewJk7eK6qmTE46hZ/ULQDw8vPzASx3VREByHTnLh4iEnF3CjFbnU0afl5 BBWCzX7eqPqX+d/Kvou4Si7eDhJ/0CA90gphFaU3bBbfEluRyF3tVt1pO4uRRg4uQA0q1qQFBWS uDJnQq0bnrzqGwu+F1MG927kij+5/eCpwKsOUWLqcONZ9Af6pKhx5rZrtkV0gvnPbzP0coY7TrM NMt0GQhws/seobdT7D4mm/UNxSga6Wz74LD7LG0yxmQQ5iEGN/N5AwnNcoaaYal2L+jANUN8Rlp P51ZXckoL/a2Qs6g9gAvhZRu6W7Kl0CLIVTsKKJhEg6G3Vthx5Fj4ltstnYdGXFAZqKa3TnghQM Eri72lvYtgcfOFBUNkoJ+FF/y2an3A== X-Proofpoint-GUID: s0MfEy6C1NYzR3uCPEHKr1bLpvlVxR-8 X-Authority-Analysis: v=2.4 cv=ReCdyltv c=1 sm=1 tr=0 ts=68f0ae12 b=1 cx=c_pps a=WeWmnZmh0fydH62SvGsd2A==:117 a=WeWmnZmh0fydH62SvGsd2A==:17 a=6eWqkTHjU83fiwn7nKZWdM+Sl24=:19 a=z/mQ4Ysz8XfWz/Q5cLBRGdckG28=:19 a=lCpzRmAYbLLaTzLvsPZ7Mbvzbb8=:19 a=xqWC_Br6kY4A:10 a=IkcTkHD0fZMA:10 a=x6icFKpwvdMA:10 a=GoEa3M9JfhUA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VwQbUJbxAAAA:8 a=1XWaLZrsAAAA:8 a=hSkVLCK3AAAA:8 a=Ikd4Dj_1AAAA:8 a=jDO9k1tB2vECKtU-ZyMA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=pnI2m26_WTs5bHz79ivh:22 a=cQPPKAXgyycSBL8etih5:22 X-Proofpoint-ORIG-GUID: s0MfEy6C1NYzR3uCPEHKr1bLpvlVxR-8 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 77473C0006 X-Stat-Signature: e7rmkc5aqn73qfgows8oj4kr7wri7mmq X-Rspam-User: X-HE-Tag: 1760603680-879490 X-HE-Meta: U2FsdGVkX1/sxmi4AP7lOVYe+a+Ib0kP+MlHOlL3UuTLieO2YRMZhFzBCOud+HdutMxDfDYTpYf57WnhABiIjkfYSMZ6kgtq+gtG4eFDRa9gqbqtCm72j0Rf3pCmxyfGyTVzO2An8XfIqAm3Kf44BYBOQhkVQo00Fe0bQGtjvkZpMi0bJx9HjEWQxP324h127krxy6ASopEiAf+TW33gqOfkYLkESv/J5t5LJrN6e1Qmr1UqvdRYFEAxYJkLwmGDa/88HPPluW357MiKjPiTm9FZBpB47cnUJI8iGpy6t/5ybRUa5ALjTRuUU2rARNcFs1VurAD7kMwV+E80gBzELb4oFTZ6B2OhzNSywXBoBjcXoRblgYWVPExW2sE6oANRnwSqzYfFhpFa8miUeXH77p/tfEr1Z4BztJHwkFLAhSLzSNyay6V3JasYZI2GWsVq4Jo7dfKGbMLPS4G40AC8ai3aCTigaqPKfs2Gc6BC52N0AdssU91EGUa2+dek6c+jIe7vGp+Ubp8lafbs/1k90f+/dVDmNazfAcJG8UbFxjSpqFlXHF4bs5xjJh9LbfTGuVCaN+c5RdB0Uuh7hMBXmovUHoKPCJPDq3wHM4YcRcrigQdxGi733rLsfJwYEIKWLShi2lBUxgoIGZU+3N0zeORC/WFLSHw8+Q61T7QVjzNQnbLUHqfhDJ/mF4UrCkT+g3Io7NtVPn8mqPAslyUzhxuIWB9UaDg9ja5FvGK5rQbY2ZPsJ5An1EK1J26E8Y0KbK6k6dVpjIM9RVR59NxsU3Q6VZezl/6vk1idT10ayVS/s4cei3tWpVoOScO6AJu8TYQXmtm+KCWEHcL3huOFPg9J8bkKgUP8UqkdvIYm4j4qQ6zuKqI/MWiMD43pbdGObqv9cyCONY26vlGcSBnPsG80OAyQs1CKQJ+9BHUkKn1XPqsHw3g4RBHK+He2e17iNu+yEXeBY7MY24HiccK jlG3I6Mt 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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 Wed, Oct 15, 2025 at 06:57:37PM -0400, Zi Yan wrote: > On 15 Oct 2025, at 10:25, Lorenzo Stoakes wrote: > > > On Fri, Oct 10, 2025 at 01:39:05PM -0400, Zi Yan wrote: > >> Page cache folios from a file system that support large block size (LBS) > >> can have minimal folio order greater than 0, thus a high order folio might > >> not be able to be split down to order-0. Commit e220917fa507 ("mm: split a > >> folio in minimum folio order chunks") bumps the target order of > >> split_huge_page*() to the minimum allowed order when splitting a LBS folio. > >> This causes confusion for some split_huge_page*() callers like memory > >> failure handling code, since they expect after-split folios all have > >> order-0 when split succeeds but in really get min_order_for_split() order > >> folios. > >> > >> Fix it by failing a split if the folio cannot be split to the target order. > >> > >> Fixes: e220917fa507 ("mm: split a folio in minimum folio order chunks") > >> [The test poisons LBS folios, which cannot be split to order-0 folios, and > >> also tries to poison all memory. The non split LBS folios take more memory > >> than the test anticipated, leading to OOM. The patch fixed the kernel > >> warning and the test needs some change to avoid OOM.] > >> Reported-by: syzbot+e6367ea2fdab6ed46056@syzkaller.appspotmail.com > >> Closes: https://lore.kernel.org/all/68d2c943.a70a0220.1b52b.02b3.GAE@google.com/ > >> Signed-off-by: Zi Yan > > > > Generally ok with the patch in general but a bunch of comments below! > > > >> --- > >> include/linux/huge_mm.h | 28 +++++----------------------- > >> mm/huge_memory.c | 9 +-------- > >> mm/truncate.c | 6 ++++-- > >> 3 files changed, 10 insertions(+), 33 deletions(-) > >> > >> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h > >> index 8eec7a2a977b..9950cda1526a 100644 > >> --- a/include/linux/huge_mm.h > >> +++ b/include/linux/huge_mm.h > >> @@ -394,34 +394,16 @@ static inline int split_huge_page_to_list_to_order(struct page *page, struct lis > >> * Return: 0: split is successful, otherwise split failed. > >> */ > > > > You need to update the kdoc too. > > Done it locally. Thanks! > > > > > Also can you mention there this is the function you should use if you want > > to specify an order? > > You mean min_order_for_split()? Sure. No, I mean try_folio_split_to_order() :) But ofc this applies to min_order_for_split() also > > > > > Maybe we should rename this function to try_folio_split_to_order() to make > > that completely explicit now that we're making other splitting logic always > > split to order-0? > > Sure. Thanks > > > >> static inline int try_folio_split(struct folio *folio, struct page *page, > >> - struct list_head *list) > >> + struct list_head *list, unsigned int order) > > > > Is this target order? I see non_uniform_split_supported() calls this > > new_order so maybe let's use the same naming so as not to confuse it with > > the current folio order? > > Sure, will rename it to new_order. Thanks > > > > > Also - nitty one, but should we put the order as 3rd arg rather than 4th? > > > > As it seems it's normal to pass NULL list, and it's a bit weird to see a > > NULL in the middle of the args. > > OK, will reorder the args. Thanks > > > > >> { > >> - int ret = min_order_for_split(folio); > >> - > >> - if (ret < 0) > >> - return ret; > > > > OK so the point of removing this is that we assume in truncate (the only > > user) that we already have this information (i.e. from > > mapping_min_folio_order()) right? > > Right. > > > > >> - > >> - if (!non_uniform_split_supported(folio, 0, false)) > >> + if (!non_uniform_split_supported(folio, order, false)) > > > > While we're here can we make the mystery meat last param commented like: > > > > if (!non_uniform_split_supported(folio, order, /* warns= */false)) > > Sure. Thanks > > > > >> return split_huge_page_to_list_to_order(&folio->page, list, > >> - ret); > >> - return folio_split(folio, ret, page, list); > >> + order); > >> + return folio_split(folio, order, page, list); > >> } > >> static inline int split_huge_page(struct page *page) > >> { > >> - struct folio *folio = page_folio(page); > >> - int ret = min_order_for_split(folio); > >> - > >> - if (ret < 0) > >> - return ret; > >> - > >> - /* > >> - * split_huge_page() locks the page before splitting and > >> - * expects the same page that has been split to be locked when > >> - * returned. split_folio(page_folio(page)) cannot be used here > >> - * because it converts the page to folio and passes the head > >> - * page to be split. > >> - */ > >> - return split_huge_page_to_list_to_order(page, NULL, ret); > >> + return split_huge_page_to_list_to_order(page, NULL, 0); > > > > OK so the idea here is that callers would expect to split to 0 and the > > specific instance where we would actually want this behaviour of splittnig > > to a minimum order is now limited only to try_folio_split() (or > > try_folio_split_to_order() if you rename)? > > > > Before commit e220917fa507 (the one to be fixed), split_huge_page() always > splits @page to order 0. It is just restoring the original behavior. > If caller wants to split a different order, they should use > split_huge_page_to_list_to_order() (current no such user except debugfs test > code). Yeah makes sense, though now they can also use try_folio_split_to_order() of course! > > >> } > >> void deferred_split_folio(struct folio *folio, bool partially_mapped); > >> > >> diff --git a/mm/huge_memory.c b/mm/huge_memory.c > >> index 0fb4af604657..af06ee6d2206 100644 > >> --- a/mm/huge_memory.c > >> +++ b/mm/huge_memory.c > >> @@ -3829,8 +3829,6 @@ static int __folio_split(struct folio *folio, unsigned int new_order, > >> > >> min_order = mapping_min_folio_order(folio->mapping); > >> if (new_order < min_order) { > >> - VM_WARN_ONCE(1, "Cannot split mapped folio below min-order: %u", > >> - min_order); > > > > Why are we dropping this? > > This is used to catch “misuse” of split_huge_page_to_list_to_order(), when > caller wants to split a LBS folio to an order smaller than > mapping_min_folio_order(). It is based on the assumption that split code > should never fail on a LBS folio. But that assumption is causing problems > like the reported memory failure one. So it is removed to allow split code > to fail without a warning if a LBS folio cannot be split to the new_order. OK fair, we shouldn't be warning if this is something that can actually reasonably happen. Cheers, Lorenzo