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 EC4CDCCD1A5 for ; Fri, 24 Oct 2025 09:59:58 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 216EA8E0071; Fri, 24 Oct 2025 05:59:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1A01F8E0042; Fri, 24 Oct 2025 05:59:58 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 040BE8E0071; Fri, 24 Oct 2025 05:59:57 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id DCE8B8E0042 for ; Fri, 24 Oct 2025 05:59:57 -0400 (EDT) Received: from smtpin17.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 6B28949781 for ; Fri, 24 Oct 2025 09:59:57 +0000 (UTC) X-FDA: 84032561634.17.DC6F915 Received: from mx0b-00069f02.pphosted.com (mx0b-00069f02.pphosted.com [205.220.177.32]) by imf09.hostedemail.com (Postfix) with ESMTP id 02D0F140004 for ; Fri, 24 Oct 2025 09:59:53 +0000 (UTC) Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=oracle.com header.s=corp-2025-04-25 header.b=UtWC+NeN; dkim=pass header.d=oracle.onmicrosoft.com header.s=selector2-oracle-onmicrosoft-com header.b=WKNVSSlX; spf=pass (imf09.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=1761299994; 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=8HNai879ittFyaIK7X0844+y204AEgAEoE/iq0gJD0U=; b=6Bwbk+d4QWeiad+P3OXlfmj0IL9il8zQfI+fq9GIqUjheKtYi+xDhqEu6LqHkm/WZUM2/S 1XYgx3LPzV56AXIkK+eNhZPQyzgTA2MN2gQF6qT0j88d4FVC+m1iPM7qD7PyCgWWwhptp+ DInoZv40hdRjTGEc5HJPrkql03p1ld4= ARC-Authentication-Results: i=2; imf09.hostedemail.com; dkim=pass header.d=oracle.com header.s=corp-2025-04-25 header.b=UtWC+NeN; dkim=pass header.d=oracle.onmicrosoft.com header.s=selector2-oracle-onmicrosoft-com header.b=WKNVSSlX; spf=pass (imf09.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=1761299994; a=rsa-sha256; cv=pass; b=SFRQ2vtiMFxpKSL1yPY0CAA/BJvFuNgrDyFMSQRarTjzSAiuwRrEI/qbzPTpn7kAbGagaE Nf0gYuLWxSSGvOvX1z+L42MkpTjDDL7ctkXDl2hl+0AA9GQaiYWoX1gqMDV7b227tSQ92E QTtGWDQLYE7fkET56CcPbWEhlF9VSQE= Received: from pps.filterd (m0246632.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 59O3NZCU019283; Fri, 24 Oct 2025 09:59:49 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=8HNai879ittFyaIK7X 0844+y204AEgAEoE/iq0gJD0U=; b=UtWC+NeNL0kuugWuISZR04apDq4cA8MnWE TDhHb8DWpPR0WDhHa6TxmenYQfN9LQUDMqrzvH7+r7Xq+xMKVmFo0BwhcB33Y1wF DGwxhZLlZEcibn4zYWS+SPIYMJ82RqE5GRQ6pw/WYGmGWKxVT9fI562giWDj0eXs gENBdCO7RFaVJhFhF1FoSRHUacg0Is5Y60R8RC0lqYy1gBkBs7OXkJRaYmbu5JxG VwQqyTw6Td+mW6M5zOfxTwvHhmo5IO2/XtXv4ELdDeKbkRpD8Ms89diAKqkeYAyw /qoN1dEgd6PWJIctWbK6+4BYikWn3I99gnSQGIWJfxtZ1gTGcC9w== Received: from phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (phxpaimrmta01.appoci.oracle.com [138.1.114.2]) by mx0b-00069f02.pphosted.com (PPS) with ESMTPS id 49v2vw3jvm-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 24 Oct 2025 09:59:48 +0000 (GMT) Received: from pps.filterd (phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com [127.0.0.1]) by phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (8.18.1.2/8.18.1.2) with ESMTP id 59O9Tmjr027809; Fri, 24 Oct 2025 09:59:47 GMT Received: from co1pr03cu002.outbound.protection.outlook.com (mail-westus2azon11010070.outbound.protection.outlook.com [52.101.46.70]) by phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (PPS) with ESMTPS id 49v1bfq4jn-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 24 Oct 2025 09:59:47 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=WN07yswxqp+MKBWOj3p/ZSzWrb+OKiBBk9TFMGTZnUXjJFbAtO7RDJCN6Rf4andUz82tKT8XL21Ye9PZQhuB5MesQNwJUEtj6HnlWQOhXwMgl40uhzYNTuUCwckBpv27tlAflDXQdVO38IzPPIFHK4e0pxtSpbQZTn/nfqBeQ8ivUHZhzLVc0jBQtCQfa7SUdvG8Z7WoZUr8y6YTzX+FIQ8TW3GAgvgMGNj9ybxGA1svrsFmRFm5OQobS11gju3JMKKe+fhmhaFs2DTCwcbJ9w03wBiB7eDk09CxPA9ezdOMO6HA2TCslPjR0fMqWMtLrRyIHuTPTDSeBgx4nBcnOw== 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=8HNai879ittFyaIK7X0844+y204AEgAEoE/iq0gJD0U=; b=Nv9gXI2yQ8ZJnUZSR4ssPMwT5sr4Mmea+Yh1CfslqoWTCT5mwGbbu0kWw6p4Kcw/j5WVEJYfym4YhaGcFP7abc/cBcR/r+qmr5nRNmlEb2fnMYCwi89mxQrigytiLiHSwxj2hkmpskWMjsZWBOMuvwQugoZgT6O30IjA/n7esM9XKAInB7OQAonWvRCiPqhEeg7+ZJ5b4pWvnORsx71Hkxf8HgIU+H1k2EzlZRfQMuu2OvsaEQB6Ffjhi/vkaBh7sDfc+j23+kPgRruRXvZAUbH3acVre0zHSzeTw82b9wlgptvtj2NSyfPrkGM3Ewf3rATojZBHnd5Rg7yB/Hc3CA== 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=8HNai879ittFyaIK7X0844+y204AEgAEoE/iq0gJD0U=; b=WKNVSSlXNqdIIagv2eJT0cD+qLvF4FDQ3wnF1B1aZ/cdUzJO1WE1Ah5BnLp06j8lfEYMcrVMQaGTpYbyNgvhH5ADeONy/4afPIli6bc4eX1zB4VyOcFYjH1ur+vrbRndIdjomNH3pTC7zRNJLuhLvHAqClRmRAegZtyFjhdQIEE= Received: from DM4PR10MB8218.namprd10.prod.outlook.com (2603:10b6:8:1cc::16) by DS7PR10MB5086.namprd10.prod.outlook.com (2603:10b6:5:3a6::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9253.13; Fri, 24 Oct 2025 09:59:45 +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 15.20.9253.011; Fri, 24 Oct 2025 09:59:45 +0000 Date: Fri, 24 Oct 2025 10:59:43 +0100 From: Lorenzo Stoakes To: David Hildenbrand Cc: Jann Horn , "Uschakow, Stanislav" , "linux-mm@kvack.org" , "trix@redhat.com" , "ndesaulniers@google.com" , "nathan@kernel.org" , "akpm@linux-foundation.org" , "muchun.song@linux.dev" , "mike.kravetz@oracle.com" , "liam.howlett@oracle.com" , "osalvador@suse.de" , "vbabka@suse.cz" , "stable@vger.kernel.org" Subject: Re: Bug: Performance regression in 1013af4f585f: mm/hugetlb: fix huge_pmd_unshare() vs GUP-fast race Message-ID: <071533c4-6e16-45b1-a094-1882d4093b67@lucifer.local> References: <4d3878531c76479d9f8ca9789dc6485d@amazon.de> <81d096fb-f2c2-4b26-ab1b-486001ee2cac@lucifer.local> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: LO6P123CA0037.GBRP123.PROD.OUTLOOK.COM (2603:10a6:600:2fe::9) To DM4PR10MB8218.namprd10.prod.outlook.com (2603:10b6:8:1cc::16) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DM4PR10MB8218:EE_|DS7PR10MB5086:EE_ X-MS-Office365-Filtering-Correlation-Id: 982814cb-2f85-4c91-de87-08de12e40f4b X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|1800799024|366016; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?q86BVON45Vknq/29GMf+tiDXCbvR1h3ORtSwwkR6saCBmqJMKPjMVMaPASV7?= =?us-ascii?Q?ip+aWhkQjTIoNccQuDowLrkBTG/qW4V69vk3MPUQpuF/yjjZ/kxDqkxKsuwS?= =?us-ascii?Q?QN7zLGr8ZjSBHg4A0+rI1vKFcKmFOQrDJKnKrdlihDXrSCK2xjv7j7f+KKGg?= =?us-ascii?Q?/J8tR/4ECcVq4TxNJDvMZeLVj+nu8n7UfSTuko746+Cs8HqVYTF9wGvEs/2C?= =?us-ascii?Q?AASFOYTvVudq7plxXj0Z0AwxkroBSXLejA8RrG5kM5gxN4U6u/pt6TiZAmD4?= =?us-ascii?Q?Xu9UfviFgV5HDJ7jUS/fKdXuujtATAU7+bq8GVX58k1M3T4j6QVdCean5Q6M?= =?us-ascii?Q?+RCOVEai0XH1o4EjX2ntLV/YSfpnA7cuaAtGxf44HcHoy8Y8KlURm9dAsGLm?= =?us-ascii?Q?9jbuwfuU3dtCCwbV21i3LhuQzOf5grMTbCx/SFlu3KxPXPOCBi+1byRdIxNU?= =?us-ascii?Q?OK5Q0KMP+6zN3BNtKpOEOZFs1Kyj7/gsRB5wwgLAiRwhi+qQxV68Cs0j+HQ6?= =?us-ascii?Q?THxHAeATuFhc7MaWrWHvjR47K989amI9W1FvZJZfsZbyET5vRRAJG9qanU4l?= =?us-ascii?Q?Jhx4aAwZQRUSF2vy5r4QmTqlfcOrw1h2bgWWesnSmpfmHV2GIuZYzKAZo0Vk?= =?us-ascii?Q?7MGA2UgnPpdQOPmoP4cfoSugTnIUTWX2SzDGt/FIjJGOZUGpHCDq2SJblvrZ?= =?us-ascii?Q?oJqY/Ffb4kyLUR4jYI1J4VBqjhyHUtg6vULExcuudGHDQDCEwpSA46jp3u9x?= =?us-ascii?Q?/lqJ9M6/OB4f93TlWWIIjAsLmyTuDTVtE7ZPW2I1j7L03nca6hkKdQRiEfUz?= =?us-ascii?Q?hz6+FKfIgAZI4Br2weW8LHz3sCg6eeRzQA/0lTDpuIptx1ni9DgEeerYjw4u?= =?us-ascii?Q?YpZX7jx0kDVc/bS8bZxlpW399WjzbVKWMja6vkNcTxGIeis40yHInEJ689EI?= =?us-ascii?Q?ALH4AE4ibpLks1MmMC5o0H6PiER1mErOLLCPeFwVeAaw6rU/9lzRchTAdR6z?= =?us-ascii?Q?RxQbnBDGv2gJQevFkzB9qmUhtc5eYxJTrSkKhkhCffLBPFGRllhxdiKC1Kq3?= =?us-ascii?Q?V5uLFQ9akun2+N6ZlPe0S6C1Uapz+abPgP2Sinx7i3T2e/hdPfALWIR6ZR7W?= =?us-ascii?Q?IOc7kp6i9O/oZfLDRi5t3QwHyktIbS4aSCpSufMD/cJd5oNfy3GByikIk0k2?= =?us-ascii?Q?1L1cUZRLFew3OLNtcb5BnZp09u1vLmqNIBPuE2kL40lmGzxg5nDeqC4FlDAA?= =?us-ascii?Q?naLDjllvt26dewDHMOzBwYDk/yU2g/6itSTCLgrDthJP7+Z5HX00AcC2scUd?= =?us-ascii?Q?aBj16yItR13WIUse0WqJZ4TZNRdBEZ8VpfWSiDNt5B2lzx1rziMra2E+k3f5?= =?us-ascii?Q?nG9+/G5ykAkj8wSeXw8XSA5kjQ6usMwOzNhla/Ne2mSr3dgKFLixkHKWahdM?= =?us-ascii?Q?C439RUCm68Gv4J08YVRuthrerT2sRaqQ?= 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)(376014)(7416014)(1800799024)(366016);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?/omonk6FtwyGLLH7JA8uTeYmHd6EwMeh5hNWToM5mz/L85f8K9SY1GnUOWdY?= =?us-ascii?Q?JYFnjT81OqdMjGlXBq+hSZqjGyU4speoIW961XrCdfuGLbImvfUp/BMlN6rU?= =?us-ascii?Q?i+TMZOS7OkJYgSWtvJCl8EKqzzU1292UHAmQs2TZeRh5oWGGqufJoRSxjrv8?= =?us-ascii?Q?T+T38CGTobi1ET0ziCB/1+TAaVrYiB7rB33zADgEPA7OwOwRvxPMnLjHrNLK?= =?us-ascii?Q?komBai9To91TNnOFsMEzCECQcZvZqBTLyT2BwBuRdzMCVhcSAmv3Qhq+EqQh?= =?us-ascii?Q?nnrhvaxB7iP63av285B3zOBs3kbVazmRNBZ7ESciC9AHIpyWdfJSINyvBfCS?= =?us-ascii?Q?o3SgNrtPiXkhS5M1IMmPK7kPHvoj02K1IUl3KtV6J01fxfs3iVh4lEgR+rUw?= =?us-ascii?Q?f8zrG0o0SxX9P/08SOUWOD42jtKvbFcgoG+VJ6YMaK0XSAuz/RmNGYAU54AU?= =?us-ascii?Q?iOSHOuzVQVo1Ctj7KONcHraHKcotMygVL6WD66fTAOMLJJEgj4F25ZQup+Fi?= =?us-ascii?Q?XIjNOD4dmuUwH/2louvX4QKP/g7ROy1svJD8fM1k8jJDAFdwoQ1KrPnkhvzJ?= =?us-ascii?Q?YLx2VwRE6etQYI6mXR59OU9P8rJ6tXQHxhExuAMB0gr2+Be/fLIiqAvXRsLb?= =?us-ascii?Q?puysjRs88KzGzW0WMOKJ0K+xbOzDsuLeBVf+yMJpnDu3kDRROBFLQVTf4BIP?= =?us-ascii?Q?mCN5qBenLTjWvOMyjMJ+uAGJZzxI2MRVtf47a9gJXyLZaGO/7Vl8kLG96ZAS?= =?us-ascii?Q?+sFn9zocQnQiAenwmK6qps8GyQm1MrgzR6zd+le7G9Zl1D2cQhPMU3ChMWzK?= =?us-ascii?Q?UzVzs0wvUnjUZa37qEbzPwySRRDvgdrvIOCwh3hD/Rav+uUBhpRIcqvZ9F8C?= =?us-ascii?Q?syPWuhycAe79JyrhhF4t9yXPns00V7w/6VXEI+MMiOS3TLFJ+IDSYvunYvVX?= =?us-ascii?Q?X0IcV9GQcCToi6Agger7KiKSPjXz+TvOrCJ6f0yKixwA4ERR3LyGmB8WfKLR?= =?us-ascii?Q?+d/J1zaZwHB6TPv9UF3O/rmtiHNCJ/+O0jObtTxxSPwIP/+2vJkLdJO2qDgC?= =?us-ascii?Q?RNQts1efJGKKe7Vehz1nfvqL2WL8n5+zOq20TyNIB+3TBdpTIcFOgPWO7LgF?= =?us-ascii?Q?c0sTJbtS2409WGTD2mBAgq9GRP15vdBmWd0bIPPi2hxc7wYyDusvDx7sZzOw?= =?us-ascii?Q?m4xOpUKHibi6hfbCj5GaYVg3qTRq9DxMRq8+kFRBZeLboRJDimkpToDaiFyX?= =?us-ascii?Q?QRsqxUofPaPraHG3rlokqw68Quhkt0WPqga2AH8bXhi5Ecec4o0Z2pMjf0AB?= =?us-ascii?Q?Zz3D3qr4iWMFxOSvo3zsjp96bAS1zHgkxMD+SAYYMNDUd4pFF2g5XE3h8LCS?= =?us-ascii?Q?oSZ6WSO3Vlc5WVa9Oma0nop1jXRZQFFfnudXHu/cc7iOmJGEM3CnljID5OHB?= =?us-ascii?Q?kvDPXrq81kBhoHJ0HNSuXtLJGTqgiuwvfqlKXQUJjVnFCUS91jsQkxoTwvPi?= =?us-ascii?Q?nbSwhH9u57HWXu5X+wEKO+DyHGk7FIfBJD1nOQwYmnUfzeTPpAPxN6H7qm/I?= =?us-ascii?Q?hQipPeuag0cNX20Y6qow9Fk624irlHZUQt7QaQxOVdvSPRODHp8Sww3/8/i5?= =?us-ascii?Q?mA=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: 982814cb-2f85-4c91-de87-08de12e40f4b X-MS-Exchange-CrossTenant-AuthSource: DM4PR10MB8218.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Oct 2025 09:59:45.2447 (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: Y6uyFx1v3qtEGOnPAAucvLefRq87Aw7gehl+9+PQCAZXTBrIPdSyihEpZrmdvaPCUuA47MFEA3JrZntm4YvqsCXP4Kw5qllJVfErO8q7e8I= X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR10MB5086 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=2025-10-24_01,2025-10-22_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 mlxscore=0 spamscore=0 adultscore=0 suspectscore=0 malwarescore=0 mlxlogscore=811 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2510020000 definitions=main-2510240088 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMDE4MDAyMiBTYWx0ZWRfXxmH4ZGK/bj+0 R0gO8ZgVNe/0LBYTe2J9N2Wb1NCLu1/2XoO5g2MPVGpKYxyWJiwqLFfpZ6LVyCmLKBDteQ6CDEm VbOJrqmVKdYbq4FILWOCFD5p1IqMF4m0p2vbs7YQH5YFPigsMHgBeelcAGENpa5ut2PxqU2+WV+ NAV7ruGJyKq0Azd5LGWzcT40tlEtoOfB9rM4IqUdPUb7or+NnkolqswYvj1aopDBeRQjvcMoMfu sSshm7qfW8spjhXsNPLpydsBo8VPASq6pXKwcSED9kNFbB5IPNTLQiDXXrcassUSoBqWRv6P3iW 5L1EScg66OlQR0mBrt6vJq/WF0HKA2XFWCwGM5g4aGmbHE8p2j6z336FvGGFOmG/559LdbwrVe8 eo2oPCBh3XSZATv52wz0+NU5gUt8/A== X-Proofpoint-ORIG-GUID: 4pe7B8SEIL6IKkFGEMWKRt_9BBCjpMeC X-Proofpoint-GUID: 4pe7B8SEIL6IKkFGEMWKRt_9BBCjpMeC X-Authority-Analysis: v=2.4 cv=FuwIPmrq c=1 sm=1 tr=0 ts=68fb4e14 cx=c_pps a=XiAAW1AwiKB2Y8Wsi+sD2Q==:117 a=XiAAW1AwiKB2Y8Wsi+sD2Q==:17 a=6eWqkTHjU83fiwn7nKZWdM+Sl24=:19 a=z/mQ4Ysz8XfWz/Q5cLBRGdckG28=:19 a=lCpzRmAYbLLaTzLvsPZ7Mbvzbb8=:19 a=xqWC_Br6kY4A:10 a=kj9zAlcOel0A:10 a=x6icFKpwvdMA:10 a=GoEa3M9JfhUA:10 a=VkNPw1HP01LnGYTKEx00:22 a=NhkHRpLaeFYgUjmVBz8A:9 a=CjuIK1q_8ugA:10 a=cPQSjfK2_nFv0Q5t_7PE:22 X-Rspamd-Queue-Id: 02D0F140004 X-Rspamd-Server: rspam11 X-Rspam-User: X-Stat-Signature: 3sa3gyfu66fnp1tpm1jc8q9x4izoh1kf X-HE-Tag: 1761299993-156032 X-HE-Meta: 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 vgKP4lG6 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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 Mon, Oct 20, 2025 at 07:18:18PM +0200, David Hildenbrand wrote: > > > > > > > > > So in case the page table got reused in the meantime, we should just > > > > back off and be fine, right? > > > > > > The shared page table is mapped with a PUD entry, and we don't check > > > whether the PUD entry changed here. > > > > Could we simply put a PUD check in there sensibly? > > A PUD check would only work if we are guaranteed that the page table will > not get freed in the meantime, otherwise we might be walking garbage, trying > to interpret garbage as PMDs etc. > > That would require RCU freeing of page tables, which we are not guaranteed > to have IIRC. Ack. Yeah Suren is working on this :) but don't know when that'll land. > > The easiest approach is probably to simply never reuse shared page tables. > > If there is consensus on that I can try to see if I can make it fly easily. That'd be good, I'd like to see that if viable for you to put something forward :) > > -- > Cheers > > David / dhildenb > Cheers, Lorenzo