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 742B5CCFA05 for ; Fri, 7 Nov 2025 09:19:26 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id ACDE78E000C; Fri, 7 Nov 2025 04:19:25 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id AA4048E0002; Fri, 7 Nov 2025 04:19:25 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 96C328E000C; Fri, 7 Nov 2025 04:19:25 -0500 (EST) 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 810268E0002 for ; Fri, 7 Nov 2025 04:19:25 -0500 (EST) Received: from smtpin03.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 3D0D912C853 for ; Fri, 7 Nov 2025 09:19:25 +0000 (UTC) X-FDA: 84083262690.03.7856119 Received: from mx0a-00069f02.pphosted.com (mx0a-00069f02.pphosted.com [205.220.165.32]) by imf06.hostedemail.com (Postfix) with ESMTP id C11CA180009 for ; Fri, 7 Nov 2025 09:19:21 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=oracle.com header.s=corp-2025-04-25 header.b=GMj5Hpnt; dkim=pass header.d=oracle.onmicrosoft.com header.s=selector2-oracle-onmicrosoft-com header.b=XX+DeFsI; arc=pass ("microsoft.com:s=arcselector10001:i=1"); spf=pass (imf06.hostedemail.com: domain of lorenzo.stoakes@oracle.com designates 205.220.165.32 as permitted sender) smtp.mailfrom=lorenzo.stoakes@oracle.com; dmarc=pass (policy=reject) header.from=oracle.com ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1762507162; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=nI7sOz/uhQ+cdqtVjqLqeS96avmFNaf811UJE33p3UQ=; b=VBeNCJeKmnsCb1pN7tO+byqrLqIza5NL5uyrGFdXoirUctQ7rGrYQnNqXGDR2uwyJ8ej58 CIczOsEAWUPV5Cadw9adqpeG7BGRdgz8hhaC2UMTmm1JaxeezGSgo6yl61E6eS4i1xHNQd O+msHfwz9HBBali41v0+LspeH9ASji4= ARC-Authentication-Results: i=2; imf06.hostedemail.com; dkim=pass header.d=oracle.com header.s=corp-2025-04-25 header.b=GMj5Hpnt; dkim=pass header.d=oracle.onmicrosoft.com header.s=selector2-oracle-onmicrosoft-com header.b=XX+DeFsI; arc=pass ("microsoft.com:s=arcselector10001:i=1"); spf=pass (imf06.hostedemail.com: domain of lorenzo.stoakes@oracle.com designates 205.220.165.32 as permitted sender) smtp.mailfrom=lorenzo.stoakes@oracle.com; dmarc=pass (policy=reject) header.from=oracle.com ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1762507162; a=rsa-sha256; cv=pass; b=k5vdnLO+edNAa7FHHOXbfvqircKfl1RK3C+eJHkWutmKlvGMNq2PFptsCJIMrG7aESgWj4 ezgu200klJbcLCGJcE52E0FsTO0OawoSMaPt4x/vz7NNQGsV4PZDCQBIY0NnNmmgKNWW2+ HjWHcNoB9g8N184LKdZdmUKK33lWcFE= Received: from pps.filterd (m0246617.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 5A78udKs009785; Fri, 7 Nov 2025 09:18:56 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=cc :content-type:date:from:in-reply-to:message-id:mime-version :references:subject:to; s=corp-2025-04-25; bh=nI7sOz/uhQ+cdqtVjq LqeS96avmFNaf811UJE33p3UQ=; b=GMj5HpntLcLD5K3U6VS0Z7mDV0jUc9BRdU a1dIM/8/bJyL/lmmKVwVMVw9QvcbNiJKVcaL87Znp9npw/EKTrahiY2jmT15tGuw R7Zjt2qeIMiIqMfszfRYhA4sU/xW7FZvc8Pky8BrmCoZOHhgwL5tfNPRXE18xF8N kC5wut2KSvLLY9LEM9Zw/paSjYl29PlAKPlcPxywFSmmy0gCuUobFxWQvTfa7Hyz c7wvmLEc0rh3A3On4cFjH/5o8lFBYz0Uq0CfpH02NkkQ/3DgwNiYE5KlYaS4V6rO Cv9jAL9HK+grmbrhK7Slmn4/mzAwJEyO7+iGHoAtG5365UJAKATA== Received: from iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (iadpaimrmta03.appoci.oracle.com [130.35.103.27]) by mx0b-00069f02.pphosted.com (PPS) with ESMTPS id 4a8yw9sdgs-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 07 Nov 2025 09:18:56 +0000 (GMT) Received: from pps.filterd (iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com [127.0.0.1]) by iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (8.18.1.2/8.18.1.2) with ESMTP id 5A78gqDt035963; Fri, 7 Nov 2025 09:18:55 GMT Received: from dm5pr21cu001.outbound.protection.outlook.com (mail-centralusazon11011069.outbound.protection.outlook.com [52.101.62.69]) by iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (PPS) with ESMTPS id 4a58nqc0n1-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 07 Nov 2025 09:18:55 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=Lh+N6QBrRBEHHoDCpELWHKKuNL3szFi7mQ3rPf18zGKYurRaku+m/8ToxVGh8il1cfNjj/QULJzqlX39iwcTvDVdb9tGKIeA6wHd0/Nss56T+xzicCaW7eF3urnbv2Lxpjv2i8i5EQvte5g4psEHAPs5pLfn/8me3cmvfAtp1CfJwprZDABhXmjtue8fhMaOpHEQsQXof93U5Z7L8JaUjy1APIHF6BUoD41jXw+8iZWlOw/te82NiBtfvLJE7vW9l6M/rO5Y/ips5UWLKGJjGdGW8mdQdhZ8E2Z0l5XmPbyg/u4ExVRZOJMqMmVytYPicRJd5HCXZJYyJM5RoJ998g== 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=nI7sOz/uhQ+cdqtVjqLqeS96avmFNaf811UJE33p3UQ=; b=ZzqS1eRhydFqW+vl2fetNwMiiuFlAEP+QfZQcEQfQjlGpWIpTJ+hPkJf3AcaVDatjSmig57ZCTbDHpGmH15LCG3KBPAFVKV/NZ0/qnJbByOEHxY72SPuQIuLcs7U4IJXwsCcQJVjnEavf4E+FoXzdvCqqrFC/Q80ECKavBlm0nKgtmYqDhYpIUGoMa14ds73mNbvpnMhbPEVIYmINZYA24+DXfVs+eTqxD7gN5ccmv41QA634iDmEcj3+NkQUbNm8QY2US76+ZUrpMvSwDgN8Xhx8uLceFlO4DBD0EDGVYdXugpdWUnpUw7e0ARUw+u1WRM1lK+RlRbqeHVS3sFnHg== 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=nI7sOz/uhQ+cdqtVjqLqeS96avmFNaf811UJE33p3UQ=; b=XX+DeFsI9zw2tunM/hNDOwhUKPUAmJas5RQ3mcf/n4r8a3oxuVbf5PcNEr+vW7YDUNF51G2+6PMckfrCavgcBVugQhJWOaBfzh/0s1r5Pr29VqDvEppHazTo6g/lEAl+14W6uiVt5kobEm2DFr7Nn3B3k0ppzobJo2uhh21VNvs= Received: from DM4PR10MB8218.namprd10.prod.outlook.com (2603:10b6:8:1cc::16) by PH0PR10MB5754.namprd10.prod.outlook.com (2603:10b6:510:148::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9298.12; Fri, 7 Nov 2025 09:18:51 +0000 Received: from DM4PR10MB8218.namprd10.prod.outlook.com ([fe80::2650:55cf:2816:5f2]) by DM4PR10MB8218.namprd10.prod.outlook.com ([fe80::2650:55cf:2816:5f2%7]) with mapi id 15.20.9298.010; Fri, 7 Nov 2025 09:18:51 +0000 Date: Fri, 7 Nov 2025 09:18:46 +0000 From: Lorenzo Stoakes To: Dev Jain Cc: Nico Pache , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, david@redhat.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, ryan.roberts@arm.com, corbet@lwn.net, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, akpm@linux-foundation.org, baohua@kernel.org, willy@infradead.org, peterx@redhat.com, wangkefeng.wang@huawei.com, usamaarif642@gmail.com, sunnanyong@huawei.com, vishal.moola@gmail.com, thomas.hellstrom@linux.intel.com, yang@os.amperecomputing.com, kas@kernel.org, aarcange@redhat.com, raquini@redhat.com, anshuman.khandual@arm.com, catalin.marinas@arm.com, tiwai@suse.de, will@kernel.org, dave.hansen@linux.intel.com, jack@suse.cz, cl@gentwo.org, jglisse@google.com, surenb@google.com, zokeefe@google.com, hannes@cmpxchg.org, rientjes@google.com, mhocko@suse.com, rdunlap@infradead.org, hughd@google.com, richard.weiyang@gmail.com, lance.yang@linux.dev, vbabka@suse.cz, rppt@kernel.org, jannh@google.com, pfalcato@suse.de Subject: Re: [PATCH v12 mm-new 07/15] khugepaged: generalize collapse_huge_page for mTHP collapse Message-ID: <4cdec7ba-373b-455a-b1d3-330246e8b2c8@lucifer.local> References: <20251022183717.70829-1-npache@redhat.com> <20251022183717.70829-8-npache@redhat.com> <7b6b5c6b-0298-47c1-ae48-17d603401bac@lucifer.local> <1c05c28a-a4f7-4562-8799-6f08a03bd3eb@arm.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1c05c28a-a4f7-4562-8799-6f08a03bd3eb@arm.com> X-ClientProxiedBy: LO4P123CA0266.GBRP123.PROD.OUTLOOK.COM (2603:10a6:600:194::19) To DM4PR10MB8218.namprd10.prod.outlook.com (2603:10b6:8:1cc::16) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DM4PR10MB8218:EE_|PH0PR10MB5754:EE_ X-MS-Office365-Filtering-Correlation-Id: 836d0ae4-eefd-4d63-f7b7-08de1ddeaa67 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|7416014|376014|366016; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?2ZcXS+juAbyvmlaif80mMVe1c4WxoG766Zslszhz7jLz9pnTiRwQg+VFyDvp?= =?us-ascii?Q?m80Yocj4ySmyyWzv4UUNgEMAmHBQo4Vv9ih916yi3iMMZC4fl+9bHtPg0ryq?= =?us-ascii?Q?NbBNETAPEC6IDEuYpSlmX2sRonXkaXcCiczMiK9fs19x10lKzvnwHoFuNiaB?= =?us-ascii?Q?+c/JlaSJzjk7iF6/swPlydiVYRpkJv0RUm0X/de9l4l6OwwLf+o29M2ueemz?= =?us-ascii?Q?e3hsf2HY6A6W7ps+iU9JdOA27C2+uYHEureOzdGiX9dmgT221wOfpkc1KvaP?= =?us-ascii?Q?aHUFGVytz4HFO44pdyFCp4YdgyisvG+9hbbNU3Jp4Ki/xzt8Qqw7xa3O4otW?= =?us-ascii?Q?Q9YMDf54D5hcvyuo7FekIyysfdE8xZH+FGHQ7HckFWvMT5dl+jEKKLMNNiIe?= =?us-ascii?Q?69z+rTR+rzv+73rV4IFtc7fsGtRK+zSciX7qQ8l0z9mSq6MlwCTyKnN6B8Mb?= =?us-ascii?Q?0DkHFubVrB4afddLPWWLREUrX7EAEo5YH8VdW8gvlRHTtIIh7hMqtsnz6j70?= =?us-ascii?Q?M7JMdY7Zew7/FL5Bs6ldwKf2Ec9bnpYZn14/+FOKTI3JXbmpqqWzNLkzLnfw?= =?us-ascii?Q?n2IUl2pMcw6EeVBMjDVFnLkl4Taaf+Aby+fkAyQOSeShfciIeDbegpBoQtVE?= =?us-ascii?Q?7oiqUSIS0K5FLTvjLZoEA4y/jfG5we66J+B8h67oXT4byASSgq7KUzTVhtg5?= =?us-ascii?Q?LYLrLz1FfG+Swp0xYij1VNTzqszBIMWHV5l6IaAJH6Wk7OmZWgfQTlvFlGcq?= =?us-ascii?Q?s5H7Fhe+MZ6Luxy3/BmUwhNJlbh/U/o0C/TH0NCC5PR8mDH6RtMqFCxddTHI?= =?us-ascii?Q?n+0XLjuU3Ix77F9mEOlDNJvXGitJnHXU6A6iAHDXQZ1hjxwkydQrlARYscUY?= =?us-ascii?Q?jNZ57E95jOLHn0LLUlij9h3Xe+4xBFaaze07M/5QrVxVDR8B/+rGeEAmIm17?= =?us-ascii?Q?oDTYsxzVi+XSQ+9/DLgDbUhWNzhnGBTZPNw/AS1dodhtDk9OncoG9Lpf1HOw?= =?us-ascii?Q?DmY7+THOuxfdWa8ZH6gKBeiGrtMfd+DNABIOT5jwcLsB8oCQOHvAr9cjZcqz?= =?us-ascii?Q?lpD8kHVBcBrbsUvJ/PVHwE2G1ckJqLKttBrjOnnyKGT1QJfptxBauBPYLGTR?= =?us-ascii?Q?O6O84aGCkVe2D7FcX1DP6WnsbkDsVtympUOr/xuv9nWw6q9FRyyPygsPlOLH?= =?us-ascii?Q?2mZj0nk/MdaW4miORL83iwQS6gx/V1KPrzidIAuRGum0abpjwYUajbmP2xee?= =?us-ascii?Q?p86fLITCHGUMPni4iF1RSeY09DXZooDA2n8EDmGVLvLvNUyoJbftd6E/lebv?= =?us-ascii?Q?zwimZeEp6MLhQVyiDbjI8n2kPhZcFUP3nZdduR3KpzeHqy0OzZl80PqIy0Gd?= =?us-ascii?Q?8sDVuarbmTsfMj+uNxKS1qqBpiEoC2ddl8D0cr7W4P7xVE8t1hdzbjgpudyI?= =?us-ascii?Q?hHRPBxAo1noe2PfvrLn1gKeMMP3hqS62?= 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);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?HpjwQgE8YBj/OfMSV++2UpecjkZpUFtLX7gZfYoY435bGu1adFJPoUVmfpAx?= =?us-ascii?Q?AgzazjJndh/bIfWlouR54VJk5/xtYsKGU6MURRgHW7AvP8SaWmFmZ/h4nkj/?= =?us-ascii?Q?yAHtn66kGDk/YqkomidyCdxaaK1NySyYC16pvNyJTR+gWbLSw3TZTuMx5bvH?= =?us-ascii?Q?ZjhVW3Ja11n5xPfwghSdiY64tmt1QJV+YzNofQzg5VVjY9R0DLzPhlUEZCiT?= =?us-ascii?Q?ypaGoczCW1F8OydX61YxeX1prGhcjZ0sPcnZuXY9wFZMAh79M68t8ZzIF78M?= =?us-ascii?Q?FHuqWRhTzOhtsytD7mwqA3dx7AjY87vk2yDsozMUFSDSoP7HR1zBycQnUt52?= =?us-ascii?Q?PRB/tlX9xnF4xt3ePlxb6RD+rGVp/IUIod1UiqN8LKhmbM0xcA8dlbRaER2j?= =?us-ascii?Q?GmM4bjV4TYJ5iZwKysOccELgeYjwSEt02cudLzpRLqLvj1q+DCTyrb1bI4pq?= =?us-ascii?Q?Tn1nktlaZN0IPqkilry/NVUgv+Aby41/UCnfkiGA9A6ndQlnAHLan9RQGF8L?= =?us-ascii?Q?k81tNg2uj8ydFiZgekkrWBe6NRPdGmnPvrBB9KF+8wVx1aOsyaCN1hZu9j7w?= =?us-ascii?Q?RMcNunoLKIwNXPhhEbUGhRAvIK9qDSR6yN0oMRKr81g5SxoTpadUlRMQf1D4?= =?us-ascii?Q?XmngvcMY/prtffqpXb1jcoYVzP+ppVT9lgbgbdxJWnC24PO8GgthE85HAsIL?= =?us-ascii?Q?8UJGy1FRa0Awe1QtB/8gr8ZKEn5gR/cIZwxfSLEmsR19Kf08huxt1/K4vM+6?= =?us-ascii?Q?slegdiKMRnA/AOR1M3pM/gHdY9Yo8XWNsbvm9m6WB+3E3d+wEiOXb1A5cY/1?= =?us-ascii?Q?4SF8ZRCZJJ178bMRdid5AXncveTq4ujGM5i8EP/VIeDuhNTMHr89ZRgDG1fo?= =?us-ascii?Q?1pnPyXnynCkbIWS7YSwOQHmCiCDW/W8h7UTi2AOIw4mId6suLFC9Ug6yr1J7?= =?us-ascii?Q?x0dMB/cna3OfbL9DSC/M4XQ8HYpCqIKjvHicBbzJnLtrj7n2WOhy2Nv/bW/t?= =?us-ascii?Q?FpyHGj30BtMj1rvvqY5Uu1DOPZ1+pgTp5+qIEnE7OX/xjD99F93Szixfc96w?= =?us-ascii?Q?yXp4urJztX6GWf25diwxBQtyVD0Wzhh34Ebn/Tkp4bCQMMCiAzctj8m5aeWW?= =?us-ascii?Q?yHF5b1vQmbj1ShvOvuro0jWtlW4Jss+Bdn5LHPoIFHSxZobqIEXh2uOQn2Xi?= =?us-ascii?Q?XnERSweJBYqsgo4QsxJHysHBo/tsgy2rH/ZKy1pepIGT+sxhxTX+yl4wv3o0?= =?us-ascii?Q?oj8gSqZhM6TygJLJ33Fmrlq0KkCcsZBmIa0KeIFJ8msyPAW58Bwrx0FoGnsI?= =?us-ascii?Q?lx9sMrIOAA0FCeGQjgBhW1ZDZjsv493m/Ie1fnLOH/lRL4CeME+wrQsf3JgH?= =?us-ascii?Q?6r2gdhfYuhk06cm1HmB6SRqjewaFWm4UxlKq2RCSVRyZMdIFNyYtXFDZEgr1?= =?us-ascii?Q?3f2/rzNFfIIStupSRtaWfgN4BDYAXv/mZkKoyqhziFzDlbrpix8Yn9+pht6d?= =?us-ascii?Q?9urj9SecVFB9qrZkBKTpcY3Ud5pcWJMbvaUBBRg68I08t4Ic1iCdoNu7lJ4e?= =?us-ascii?Q?B7p/OUPCLJsaOKERgdMjLNTlb6lRAkecTKmS100Q5KxBem9g3uNhA4YjBj9J?= =?us-ascii?Q?gg=3D=3D?= 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: 836d0ae4-eefd-4d63-f7b7-08de1ddeaa67 X-MS-Exchange-CrossTenant-AuthSource: DM4PR10MB8218.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Nov 2025 09:18:51.2821 (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: Oq35nsg6k/+ehPchRZZ+HMzvNY+6zEVXcHpv+te/DIwLCp4Q8e3f1h6y6LYYUjh5n6tzbBwYSq+RpOpDhvAHBuhx6PT3588/1CVOJfzblcI= X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR10MB5754 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2025-11-07_02,2025-11-06_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=806 bulkscore=0 spamscore=0 suspectscore=0 mlxscore=0 adultscore=0 phishscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2510240000 definitions=main-2511070074 X-Authority-Analysis: v=2.4 cv=GJ0F0+NK c=1 sm=1 tr=0 ts=690db980 b=1 cx=c_pps a=qoll8+KPOyaMroiJ2sR5sw==:117 a=qoll8+KPOyaMroiJ2sR5sw==:17 a=6eWqkTHjU83fiwn7nKZWdM+Sl24=:19 a=z/mQ4Ysz8XfWz/Q5cLBRGdckG28=:19 a=lCpzRmAYbLLaTzLvsPZ7Mbvzbb8=:19 a=xqWC_Br6kY4A:10 a=kj9zAlcOel0A:10 a=6UeiqGixMTsA:10 a=GoEa3M9JfhUA:10 a=VkNPw1HP01LnGYTKEx00:22 a=1B0iEbWH250DWWesQxkA:9 a=CjuIK1q_8ugA:10 cc=ntf awl=host:12101 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMTA2MDEzOCBTYWx0ZWRfX1xVDEm1dbWIG RnFPmsj3rlD/9hY5a9WwPIEAyeSq8lR0mY38IjywGaBOvdm4jsg6qtU7yEujWnH8EjSqYCgeo5Q BoIWpmC8aEL4kcvMtdVLHBGPF7Yq1mZLaFsKsDRA4MGcGtstC38/9Q640JhhcKrWzxECfO2907e ziNvfG2CPnyrL2aLCD4InclZaIXsi1yE31qwRKZSicMXGg7jyVxz2tTK9L1DZu4BppSIASJdCg9 FPxAgO/brd6/Nv4J/kegz344mkz2ABxzqc5d918bg255zEhNb1FzgpQCNUqZqIw4/XO7Q7unDUE ue3fq+Nd6mhUWEof6utKDtP9+B1zWr9AdyG+/SBalyJPp1RQNLeZ0erinZ7krWhmTZIOIChvKm+ jf9m4mppEG1O6HrgedQPQEKJ6u0hZP78KAgM7zteG1U622ZLh48= X-Proofpoint-ORIG-GUID: ObbOKpXAdXfnS9fYN3zOGk38wzxnMUta X-Proofpoint-GUID: ObbOKpXAdXfnS9fYN3zOGk38wzxnMUta X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: C11CA180009 X-Stat-Signature: ykpxd49wqrsym43qk8xfrmd6b37w3kz7 X-Rspam-User: X-HE-Tag: 1762507161-31193 X-HE-Meta: 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 zSdt2MmB 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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 Fri, Nov 07, 2025 at 08:39:03AM +0530, Dev Jain wrote: > > ----------[snip]------------ PLease when you snip can you not snip way the code being referenced? That's really unhelpful and now this sub-thread loses a ton of context... > > > > > + > > > + spin_lock(pmd_ptl); > > We're duplicating this in both branches, why not do outside if/else? > > > > > + WARN_ON_ONCE(!pmd_none(*pmd)); > > Hmm so the PMD entry will still always be empty on mTHP collapse? Surely we > > could be collapsing more than one mTHP into an existing PTE table no? I may > > be missing something here/confused :) > > After this code path isolates the PTE table, we don't want any other code path > doing "Hey, I see an empty PMD, let's install a PTE table here". One of the > reasons why all the heavy locking is required here. That wasn't the question, the question was why are not able to install mTHP entries in an existing PTE table. I'm obviously aware that we need to lock here. > > Also, I want to ask a question about WARN vs BUG_ON: suppose that the > race I described above occurs. After khugepaged isolates the PTE table, someone > faults in a PTE table there, and eventually writes data in the underlying folios. > Then the buggy khugepaged nukes out that table and installs a new one, installing > an mTHP folio which had old data. How do we decide whether such a condition is > worthy of a BUG_ON (leading to system crash) vs letting this pass with WARN? To all intents and purposes just use a WARN_ON(). A BUG_ON() is almost never right. This has been done to death. Probably the WARN_ON() should be a VM_WARN_ON_ONCE() because this is something that should simply not be happening in practice. Or can make if (WARN_ON_ONCE(...)) abort, but then we complicate already very complciated code. > > > > > > ------------[snip]---------- > > Thanks, Lorenzo