From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0b-00069f02.pphosted.com (mx0b-00069f02.pphosted.com [205.220.177.32]) (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 6A8972E36EE; Sun, 20 Jul 2025 11:05:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=205.220.177.32 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753009541; cv=fail; b=P1ENS77L4Yn1WNQ8A90gUZ6ffXz9J9wuuZr08Rc+qOpyq3EY2rKe2HQ6IQ9G0TPZxjmB5HaF2XLBJ0CQH3WksZF6eFDTcQmj1vouOUeY758aFY5SGeCQQi4+BQxwxpH63fa+6dxFifI6Y5TTV3fLvDGgvv0X/Cl89QogRKyKiyY= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753009541; c=relaxed/simple; bh=8BZm4KYkzukrczBVGUT4BtH3/b2M2KiH8rp9igDTaSs=; h=Date:From:To:Cc:Subject:Message-ID:References:Content-Type: Content-Disposition:In-Reply-To:MIME-Version; b=gwpkqaPtyslv9MKq//r0hMUAwScwm2CgBDGxYsSUNUUqeo8yw7O9SOFvwBU/HK8H8GJYrizZp9bMlhS826xZpHNJ2xWlF1YhKtyB5hCAmuGkIh6oW5zWKsJAQ5saFch0c5ECVXb4GWFsNDskXBO6cZQQ/hbsnlWKP9E+wp9PTW8= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oracle.com; spf=pass smtp.mailfrom=oracle.com; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b=nVBSfPPg; dkim=pass (1024-bit key) header.d=oracle.onmicrosoft.com header.i=@oracle.onmicrosoft.com header.b=BfYuyrZ6; arc=fail smtp.client-ip=205.220.177.32 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oracle.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=oracle.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="nVBSfPPg"; dkim=pass (1024-bit key) header.d=oracle.onmicrosoft.com header.i=@oracle.onmicrosoft.com header.b="BfYuyrZ6" 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 56K4lm6c032040; Sun, 20 Jul 2025 11:05:03 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=9FVVB80wixZwXbhy7Y PDUs1vkgBRLRDvh3ZhlcjnIVI=; b=nVBSfPPgbS8xGTZzh20yP6nDuH1hsl5O32 POReoEC/9SsEgQaFQC5G9194jszqwiO6MJ3y3PyxMR/L3pKCbP9Im80KLwCaV/Q/ cde7uvR+waZtA/BuQBpsdtYfb7faw85Pzm4DClkCd0GH9epsj79OkB5GZ6KEN0Rh lpzBC8HQbG6fVA4UpJxy6rTbcvZy9WbNc2STisuYZSnFL8tdOb2TyAYPQkJLesAf g6GY+iUn/quVXmN/0VE8jiD8gcWfst/zu33Vh10AhXBCnA+/rlj5MipjPjCQ7vJW s6CYmQ/2wzqmu/fmxHgTspvgRGW2mW6dOm5aJHNtCt24QXugQfBg== Received: from phxpaimrmta03.imrmtpd1.prodappphxaev1.oraclevcn.com (phxpaimrmta03.appoci.oracle.com [138.1.37.129]) by mx0b-00069f02.pphosted.com (PPS) with ESMTPS id 480576h6h9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sun, 20 Jul 2025 11:04:48 +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 56KAmLEv010797; Sun, 20 Jul 2025 11:04:47 GMT Received: from nam12-dm6-obe.outbound.protection.outlook.com (mail-dm6nam12on2085.outbound.protection.outlook.com [40.107.243.85]) by phxpaimrmta03.imrmtpd1.prodappphxaev1.oraclevcn.com (PPS) with ESMTPS id 4801t74f18-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sun, 20 Jul 2025 11:04:47 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=qDQcdn+2/T+fNpC1xDYyMMo/vfg0psrPO43RHKebExbMgFmlz4J3WfkcP9yzHn4C0inzHutIV9h70ZCzFgj8yF0z/h6p1WZ9noLe6dfW9eNpCeM3YJZuqcr2hyNm8vdUoZV3dDGcSkThfJOYSvz66f59SXdMSyjcw5DS6YkO86L8RI2OUOs6uDs67YkHxDPcK8JPY2Dg75elfaAP8cjo3sWmgZGhxk6slafTMNVlsjZLZ3odYWa2yMEKefdCoYGSqUpv/6RmQzx+DTIEucCvN6arT+Rqhz5ka9W/mWZ5fglFo0Xs4YbVC0ggP2XR758Fe2rQfbSArWOb6rAjWlLXcQ== 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=9FVVB80wixZwXbhy7YPDUs1vkgBRLRDvh3ZhlcjnIVI=; b=xIQq85BUdN8CgGstjd0NTduRHs+9g0E1Y3BpVub13EUFR10lbDOVubIZ423rJiqnOz+WKLZM2cKzinyacC1ecdacxbpiwfJlLrVP+wQMsA2quX+Tnpv4v8whjkU2bNJu1R+hiVVluRI4FHd/LHNzOSpdD52fuENpgF9VHQzon0hnvJTzu2iYZx11FARBOsoiDy8XvUy1gV5tu4zvGmc1bIZlEOlQ26nTVaMCp5GP2PEgelwJ0TRT+n3Uidz6mjiS+J17dGwhOBCffYEOCBpnzHQul12qCiBPW+blSfoIqdFzXTuP2q0B3gpHAYoJOKLvPvBTJKDz6Wb1Ta2LU26lMA== 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=9FVVB80wixZwXbhy7YPDUs1vkgBRLRDvh3ZhlcjnIVI=; b=BfYuyrZ6qNxrMEy+B+Q894QC0yI1NXASEQ9mrCO/ad1IQfGivm9KRkTYh2wCCH1VKB/SsVfk0jCibFdJVDRFRQdVw0ZjVnnG1Kb+4djtJaV8ssm7vNC6cgv31xE++wXL3v5enQyU6R1gXTX+pehsL6P23l3DbEoju64B2D6uvB8= Received: from DM4PR10MB8218.namprd10.prod.outlook.com (2603:10b6:8:1cc::16) by MN6PR10MB7465.namprd10.prod.outlook.com (2603:10b6:208:47a::13) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8922.40; Sun, 20 Jul 2025 11:04:45 +0000 Received: from DM4PR10MB8218.namprd10.prod.outlook.com ([fe80::2650:55cf:2816:5f2]) by DM4PR10MB8218.namprd10.prod.outlook.com ([fe80::2650:55cf:2816:5f2%4]) with mapi id 15.20.8943.028; Sun, 20 Jul 2025 11:04:45 +0000 Date: Sun, 20 Jul 2025 12:04:42 +0100 From: Lorenzo Stoakes To: Andrew Morton Cc: Peter Xu , Alexander Viro , Christian Brauner , Jan Kara , "Liam R . Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , Rik van Riel , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org Subject: Re: [PATCH v4 06/10] mm/mremap: check remap conditions earlier Message-ID: <8fc92a38-c636-465e-9a2f-2c6ac9cb49b8@lucifer.local> References: <8b4161ce074901e00602a446d81f182db92b0430.1752770784.git.lorenzo.stoakes@oracle.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8b4161ce074901e00602a446d81f182db92b0430.1752770784.git.lorenzo.stoakes@oracle.com> X-ClientProxiedBy: LO4P123CA0174.GBRP123.PROD.OUTLOOK.COM (2603:10a6:600:18a::17) To DM4PR10MB8218.namprd10.prod.outlook.com (2603:10b6:8:1cc::16) Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DM4PR10MB8218:EE_|MN6PR10MB7465:EE_ X-MS-Office365-Filtering-Correlation-Id: bebd8e44-83cf-42d9-14ff-08ddc77d3bfd 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?IzMMeoLTnzofTAUatytQjBjjbycdP5zxoRmHJSSqZD5ex32zQvKKImIG0mQh?= =?us-ascii?Q?0a/4KHFBOYoWVULrFB90PQeWqKGjFitu9jeUSXMyDKGg5raUzWDncXldwEFf?= =?us-ascii?Q?zSvltHoFbc43/LbvxH4bYhOeEA9ih672UmjzL7Wb4docQd7dVhxP1mM8dIOX?= =?us-ascii?Q?1so3lT+7aRvBhSaOFp6j0hP3lgqH1HDKAkqVJ4VsBrzcaIxinhSnkD9Mrq/1?= =?us-ascii?Q?Xdj6T2JUpcO8BwSaO1McArp5Qm8Gcx3FJUypPWWS+WTnFUSzQ/owDfNQK3qy?= =?us-ascii?Q?nJSIuZI+VoMcqC7fUXJfQU+JI2tWKfh0Mi7MxRtxvUipzgWtLMWwNNdK7wc+?= =?us-ascii?Q?k5W5gX3o54+VaZk02N23zHpGIWByOmy8aN6JCtdrCMy60RZ+SWpTLhPUfdL0?= =?us-ascii?Q?ZUeH2xUOLNyKVyw0/lPDWiI/ycbaMDDs+qnuGNmuwELw0Z19k1NESWcQ8tD1?= =?us-ascii?Q?DyLjgf88P4Uyje8TVVbOqCoQK7tQWykB1dMLbxI7zCFbpNhvv3oF//m+Mmon?= =?us-ascii?Q?/ioTxfT28MN0coRcX+T03W+EcY2zWcS7A8pKOXs742Za4hiYynAEs2koArEy?= =?us-ascii?Q?hsBIU5MbTl8GXt8qA8W2zGFgWOQclgMrsYJ3PoD+TDPnao3eQa949JnFzE60?= =?us-ascii?Q?byhvtS4HTI4Ubg93RxHos5zVUZgFyKHhkzFPljXGrQGvbigkMb4MEFyOgozO?= =?us-ascii?Q?4w9LSQUrTG/Uj8cUbwNmN8C4GP5QYxDe1Dy+V3yr8Lwvprz0evvDqsJPQ1bV?= =?us-ascii?Q?naAycid2UJ5HSBxknpN+Kq1f30f7V79mlO8zSPwYKdmlwMxBSyWyL6/XcOzd?= =?us-ascii?Q?LjqtfI16fjhnMzzoRI6jKM9F/S5+EzSKerXlS7uSyIuQeAEpeJbm1Tuj7ikm?= =?us-ascii?Q?EH9Lh8mRjXSJiI5bIOD2J9CkHX7ClwrFXNsrdEa5oaOaxNLZQj/59Lsq/gQz?= =?us-ascii?Q?My3doa/9mZV6eaEFw3hraw04PPIXcXT19jI3Py8dI0kOF9gRFCEiPR4+YCMN?= =?us-ascii?Q?0LO/0tqZYeVduPFHs1Wm5CeJpGjB4cdeaBOaHtpoB/NG4Vo8Au2HIOscqNPl?= =?us-ascii?Q?H7o8KIjcJOznUZ945qRxrVEb8RP2tXR7of4l0O3JUmkcwh0vfJf0nUMMOPb9?= =?us-ascii?Q?29SmJSC76/cGJcGeQiY18Xh3FVOqTEXsQ5SUMl4i+0lI5qvS7+18FqlrM8sK?= =?us-ascii?Q?hAvPgFJExtEPdN2bYabBAheMBBuWxbs8flB4lp9xspcxFyZDrORfj1g8xQYV?= =?us-ascii?Q?rtXRA+Wf/j7/ZPlT3tbv26ZwTIUQsbstL+roxrksM/MHJSa7ky2kVK2fv9Rb?= =?us-ascii?Q?XzSFmUw9dsLqhcehXBgoqc/vwN0kbaRYZfjuNAhSJsLjQ9ZFCYWw26MWUPQ/?= =?us-ascii?Q?vCLE5XiWJNXu1Sb1a0Kqwy7JbJq7/nMbL1Acw7uYwDRAwYknS81ILp2ujAKf?= =?us-ascii?Q?OcCgSL0To54=3D?= 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?DK7nuyOzNE6gRqalJUrtDhyy/Sd/5t9ID/UYnKpcvfJFB5TgvlIZQaN6/usb?= =?us-ascii?Q?BPVeZD0qxbsT4TsMXjNJdy7g3PMhFa4wKog/M7biTN2kw5MwPpZuiV0eXVXK?= =?us-ascii?Q?4pcSKwzmThiNYVxbnxkdfKv2D4B5brZ2+pMvO2ug+k7/5uOOKDBEOpp5rvGB?= =?us-ascii?Q?avc8ASSxxaA65lwG52+NNcF1ixuVakLkSMolTeH48eolRLJnOWOLTzUBKbnW?= =?us-ascii?Q?aVKg1e2h5ktpW2iZF1rAFBQLLD5t7HOr0cAfZi1N4Z86OjIIKrwUjGXGt6Sc?= =?us-ascii?Q?KNCHsR1zA+93Fa/IYH+RphiR0Jlg9Mq1QUWMYpSx7GFIs6bbjhY0AZc5oG3t?= =?us-ascii?Q?98sQ0NS5NnJzWhDYTO1pHksTWUfBVcn9HwTBPv5WROrIZUWCJZdbRRniQ9zz?= =?us-ascii?Q?ZqY5na6Z5L/uebxtux2w3W4ZqkoH4NWi8Z1ewT8xeQ57Wct50ndBu76BQ0Mu?= =?us-ascii?Q?iM+02FU4sN1XR9X2fGsXVbJ+V9hPL3G5bvAfgt/chTXkB2I7pbsadGDfWthD?= =?us-ascii?Q?9Ncyy3FRF4y9Fsb2nbt9QSqde0h/6JaRiX33UC3IqhEGGO9jEEMvKlPqzDdN?= =?us-ascii?Q?o/sLSCskYva4YjFGuudr6vcyoztEdnJzoWZ7NpkIHE9QcDUrbuQ0C8WCW8tZ?= =?us-ascii?Q?LCatymOJ25KU7y1pyaSuJKDYRQjahBU08cFt9oWGEdVP13HX+dPQjq4oKG4v?= =?us-ascii?Q?zTyZN69mK/p2vfLFEm6BspB1GkeTeueMPAKnm+KzE3rPdwGU4gLxaKCw6yf9?= =?us-ascii?Q?O3eu8nNTsDYD96avyYzBKJNgqCSYBcoWnXvQ7l05flhWDSaEGnqlDThfA1D7?= =?us-ascii?Q?m1cnj8EHbKww/pf+XwNiGTj28N5CmlEsCS17lR9rbTyX2F9HOsrMNv/f6IbG?= =?us-ascii?Q?s496QaKMknuQderJ8HNfhcZZ9B/BRwhq3rp00zDo5eeshEkNe6VrikysccXS?= =?us-ascii?Q?O77Jx8DISz6F5T3uT1eXHLsosx3K7DW30v7N17WeeklaNPwiv4SWy2zuKAlP?= =?us-ascii?Q?B5e+IEmr6+lVnZ/ovoPn4Qinw39NPoSevD+KNyBCSChoWuP+Iv3KquSNZJml?= =?us-ascii?Q?RvIp/8LqmSkrPWZsMLf9h5UUaj8WtsUz4lDchxauBKQyZBHajRcWA1PEtu9U?= =?us-ascii?Q?LIHsM6+E2pcQb8h7WXuOGquK0P+6VLhfUe56Og1Tm7/E7mgJI2qUzwtWnoFe?= =?us-ascii?Q?fVNUf1f+D/OCsfMZ96qtb+WZJM8gYtbSDMpkSwKvBK9jMAoEINVOCirJJFpS?= =?us-ascii?Q?P0bt7U8hXeinjJGonJh4wRPHkkEYoNecU3UhVd/ZCZGizez8CAMQ4q/Wb+AV?= =?us-ascii?Q?U7znOGVR1TqNyz0EhVOjE+dtFVyFyKIuz4KNRIlDQKryAUbZSy2GDXm9sJlp?= =?us-ascii?Q?2B+vXT3s/LdRPHzUw30JVE7iCPWpukilvMU2uKwZ93VBi5XwBv2uPdOU/7gZ?= =?us-ascii?Q?x/3S+lBkO7o/2kIeVqw9YnuR5vBNxN4vGpp5/sy+gBOGZ8fQ7QS0g8ZTlKHl?= =?us-ascii?Q?PmK9KIODSz6DDpY+nD6O4rVTsQLGKEiLtxnT5sMq7NwSfnzhq0hQZAnzvtMD?= =?us-ascii?Q?gtZu3+3kQSzXJVdJ/3aU5ZrmqkbSUcOWKy/+M7GcUD07Brl18vP2btMTvxqZ?= =?us-ascii?Q?fQ=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: bebd8e44-83cf-42d9-14ff-08ddc77d3bfd X-MS-Exchange-CrossTenant-AuthSource: DM4PR10MB8218.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Jul 2025 11:04:44.8948 (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: 8I7pQYTwdGUHdXphpfW41YJA2f5Qw2lUHgLyYV/zWA+r17UaafphhFF2fodEsc+5jVbUwd+yNes09wmg0l8RXSo1JH3r+xDy+Krk5Kjn6FE= X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN6PR10MB7465 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-07-19_03,2025-07-17_02,2025-03-28_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 phishscore=0 mlxlogscore=999 bulkscore=0 adultscore=0 suspectscore=0 mlxscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2505160000 definitions=main-2507200106 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNzIwMDEwNiBTYWx0ZWRfX/M2nNsip85Rk KMwLlVP6qRa2w6BWZBYVHe4PWCttr0BT9K1HyN7dr/fRXJvNmV2Lmaxz1A8fxoFtgr7z+Ea3V9z HIr0/dD8H6S2x2/SiEihXrj+jLXwcYSEcajWQ0h++iF7+Y2LpohW2SHJ/ziQylFytSHxrH3o0pi lqkrdNnv3IhMZdsa1jqy1ZoF1ykxN5hrCC7oPGQfZoXGV4B0WtTWY3rukn8mim0+6P2aJLsusbk TPR/4eMPiU+rZuhsbWAw5thBAnOX9uG9unTiNf4QexNbrchdRtO6C0+/eYheZZzRVqXQAo9NUpr SYJxV022DMXhPrfYPIxthiIY9rQOghGm2x4uy+ReU4zdMogGvTSniIWkvXhQrXDnQGJahJafWck M5Nh6RzHyxUIWvFGEJNTTAiMTM7L21MEx4XkQbMq5rk8Uhfzxxru8hxOmjqSKvF0bmeO/sgL X-Authority-Analysis: v=2.4 cv=doDbC0g4 c=1 sm=1 tr=0 ts=687ccd5f b=1 cx=c_pps a=WeWmnZmh0fydH62SvGsd2A==:117 a=WeWmnZmh0fydH62SvGsd2A==:17 a=6eWqkTHjU83fiwn7nKZWdM+Sl24=:19 a=lCpzRmAYbLLaTzLvsPZ7Mbvzbb8=:19 a=wKuvFiaSGQ0qltdbU6+NXLB8nM8=:19 a=Ol13hO9ccFRV9qXi2t6ftBPywas=:19 a=xqWC_Br6kY4A:10 a=kj9zAlcOel0A:10 a=Wb1JkmetP80A:10 a=GoEa3M9JfhUA:10 a=VwQbUJbxAAAA:8 a=QyXUC8HyAAAA:8 a=yPCof4ZbAAAA:8 a=5W1CHJM56yEcQmTypBkA:9 a=CjuIK1q_8ugA:10 X-Proofpoint-GUID: 4V6fym9tyLFQr9EEUIaBNQNMQzpgWKaX X-Proofpoint-ORIG-GUID: 4V6fym9tyLFQr9EEUIaBNQNMQzpgWKaX Hi Andrew, It turns out there's some undocumented, unusual behaviour in mremap() around shrinking of a range which was previously missed, but an LTP test flagged up (seemingly by accident). Basically, if you specify an input range that spans multiple VMAs, this is in nearly all cases rejected (this is the point of this series, after all, for VMA moves). However, it turns out if you a. shrink a range and b. the new size spans only a single VMA in the original range - then this requirement is entirely dropped. So I need to slightly adjust the logic to account for this. I will also be documenting this in the man page as it appears the man page contradicts this or is at least very unclear. I attach a fix-patch, however there's some very trivial conflicts caused due to code being moved around. If you'd therefore prefer me to send a respin, I can do so. This doesn't reflect on the series itself, which with the corner-case VMA iterator stuff sorted is fine, but is rather just an undocumented and unusual behaviour that it seems very few were aware of. With all other tests passing this series should be fine with this fix applied. I've run all self-tests and the LTP tests against this. Cheers, Lorenzo [0]: https://lore.kernel.org/all/202507201002.69144b74-lkp@intel.com/ ----8<---- >From 23b95070152b22f7432c4a9da9e4b5718f9d115f Mon Sep 17 00:00:00 2001 From: Lorenzo Stoakes Date: Sun, 20 Jul 2025 11:41:48 +0100 Subject: [PATCH] mm/mremap: allow undocumented mremap() shrink behaviour It turns out that, in apparent contradiction to the man page, and at odds with every other mremap() operation - we are allowed to specify an input addr, old_len range that spans any number of VMAs and any number of gaps, as long as we shrink that range to the point at which the new range spans only one. In order to accommodate this, adjust the remap validity check to account for this. Signed-off-by: Lorenzo Stoakes Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202507201002.69144b74-lkp@intel.com --- mm/mremap.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/mm/mremap.c b/mm/mremap.c index 20844fb91755..11a8321a90b8 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -1339,11 +1339,18 @@ static int remap_is_valid(struct vma_remap_struct *vrm) (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP))) return -EINVAL; + /* + * We permit crossing of boundaries for the range being unmapped due to + * a shrink. + */ + if (vrm->remap_type == MREMAP_SHRINK) + old_len = new_len; + /* We can't remap across vm area boundaries */ if (old_len > vma->vm_end - addr) return -EFAULT; - if (new_len <= old_len) + if (new_len == old_len) return 0; /* Need to be careful about a growing mapping */ -- 2.50.1