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 C3850C00528 for ; Sun, 30 Jul 2023 16:56:01 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 34F5E280005; Sun, 30 Jul 2023 12:56:01 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2FF10900002; Sun, 30 Jul 2023 12:56:01 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1793D280005; Sun, 30 Jul 2023 12:56:01 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 0C032900002 for ; Sun, 30 Jul 2023 12:56:01 -0400 (EDT) Received: from smtpin17.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id CA4601C8B7C for ; Sun, 30 Jul 2023 16:56:00 +0000 (UTC) X-FDA: 81068880480.17.C9ED10F Received: from mx0b-00069f02.pphosted.com (mx0b-00069f02.pphosted.com [205.220.177.32]) by imf17.hostedemail.com (Postfix) with ESMTP id 721F94000A for ; Sun, 30 Jul 2023 16:55:57 +0000 (UTC) Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=oracle.com header.s=corp-2023-03-30 header.b=hkAgEgIs; dkim=pass header.d=oracle.onmicrosoft.com header.s=selector2-oracle-onmicrosoft-com header.b="TG/piX2Z"; spf=pass (imf17.hostedemail.com: domain of chuck.lever@oracle.com designates 205.220.177.32 as permitted sender) smtp.mailfrom=chuck.lever@oracle.com; arc=pass ("microsoft.com:s=arcselector9901:i=1"); dmarc=pass (policy=none) header.from=oracle.com ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1690736157; a=rsa-sha256; cv=pass; b=xRAFluGbMWSAsVtlXWx12JiMZ/QsJASLFFKJyj9dc3X+/vocr4WYWogbUkBkW04SzdBd7m TyuDMNI193SpJG4Qj+8ZdP9XGN1Bv3bVQdvUqThgbcPQN4DbpoE7grPwc1nFENwOE4Q90W IwIgtG5lhNgOavTuU3rQdxXAVhJUnGQ= ARC-Authentication-Results: i=2; imf17.hostedemail.com; dkim=pass header.d=oracle.com header.s=corp-2023-03-30 header.b=hkAgEgIs; dkim=pass header.d=oracle.onmicrosoft.com header.s=selector2-oracle-onmicrosoft-com header.b="TG/piX2Z"; spf=pass (imf17.hostedemail.com: domain of chuck.lever@oracle.com designates 205.220.177.32 as permitted sender) smtp.mailfrom=chuck.lever@oracle.com; arc=pass ("microsoft.com:s=arcselector9901:i=1"); dmarc=pass (policy=none) header.from=oracle.com ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1690736157; 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=Q9ZUIT1iO+MuMRYHr8siU7vWoEa0y0X8JBKxxx05Kds=; b=5DZGoyMDj0nTs5/OsTrTGza2+0UoCbjR71E4+GYxBX+zRSVbjjQsxhiJIIKBozwsCzfI0N 2J2iZoxgdlhxtFu767p9mLNhHOHieQwFSs7JvUCnNnbla4kkn5rTz27k15ouGiQi8VPOAl hVxUhtmf1zowCA0BkRmjkNC3biVDU5E= Received: from pps.filterd (m0246630.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 36UAEQLv004393; Sun, 30 Jul 2023 16:55:46 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : content-type : in-reply-to : mime-version; s=corp-2023-03-30; bh=Q9ZUIT1iO+MuMRYHr8siU7vWoEa0y0X8JBKxxx05Kds=; b=hkAgEgIsdLy7QeBPIIlwYEky+r0cfVOu8S/K2yg8IWVFk1Rbe9ydxZxpdzbDOMbiNygM 9lHCA/usb6DsM9fCkAuZYJpMPE73H+o872Z0SYV8TZntKkQMprAwvgLDP7olpUr8v4h+ gBpnfQlkdfqeV7nxY/4uONAls2MLQOjXpgNGoujeQq+nnomljJ4ceinqgb5tdmo4jixs Kxh1yn65AB2AEp3qYTDunqr8kYuJTFKlx+d8KYuhBRLqZwI3jnee8j9DNZQaznjGBXAI erx8IRa2KfEkkNjTAW0Lzpawg5b8cTxIusRtOfeUjNFjKjpuanmG3jDMAqcGe758P6Nh Cg== Received: from iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (iadpaimrmta03.appoci.oracle.com [130.35.103.27]) by mx0b-00069f02.pphosted.com (PPS) with ESMTPS id 3s4s6e1av8-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sun, 30 Jul 2023 16:55:46 +0000 Received: from pps.filterd (iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com [127.0.0.1]) by iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (8.17.1.19/8.17.1.19) with ESMTP id 36UG5Pgp008734; Sun, 30 Jul 2023 16:55:45 GMT Received: from nam04-mw2-obe.outbound.protection.outlook.com (mail-mw2nam04lp2169.outbound.protection.outlook.com [104.47.73.169]) by iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (PPS) with ESMTPS id 3s4s79w2ek-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sun, 30 Jul 2023 16:55:45 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=fU6G47doIh1pA6efCMifu0jmaK5T/Kuc/RzgIDyCTqByNeWHVP8A0Ln2QbER0VPaCms42Whk3skfVnCdtH1chZa/h7Carji4qJXb4mBrAPGn5XTbUmJuCnCAi39ECr0VSnSwhVCuUCndoYwX8GWjcxu8grLCYPDh3ACN/dcMg4KGbYSXtt/LjeLykXfA6XEdVa7f9KI6K57glsOo82nAeUCpUjhFyJUXiEq44NrIM8kwPpO2eGVDw+yvF5lRGYPTWhKkGsjzogjx8PDFmBI/HQnfRh2QlWYclHKHG2iXztDPG81ABGpmvlRTNX4xasi5BSLlL11NFTMqngMfwlNSWw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; 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=Q9ZUIT1iO+MuMRYHr8siU7vWoEa0y0X8JBKxxx05Kds=; b=XZKakaoDYTU3eIJY3WIUKM9bMo9fQ5xGvplLbjatZHasBg4d3M3ahfI15mEQJ1snUfk97M2MjjhM4kYFc52ZDxUmI7BnM1k/7Y+JESvf3gt4oZN2UdaJJHMJlNQ+NOWFt5m6som+rZ0xcbLqIJEU+CXoehsoEz+GT4E8EZuoKadXEGpoWVh3U4ENYZk0elVvO/RnejdK4Yq0YijCFB+raglBqR6OqxPE0UrHDvgA/trkNhZVxBkpN976eX+X2kRHlksJuT6jjl2lYXxSgaq7z1I9fBcmCWo1F6AWiN8/kg9rJa757hEDwUBfSMyR0LWoxPFAyqiIf3bhyfmNLwNr5g== 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=Q9ZUIT1iO+MuMRYHr8siU7vWoEa0y0X8JBKxxx05Kds=; b=TG/piX2Z9D5qz1x22i4dSdO2Wc59PEbDg0s52quRo0s8vnvj/VWn9ZZuvoXOUk9XxZSGY2V6nzK/dKLlxoswKMjbV4K2ctKALzRTzaNSspITsijggnawIfWx6RujQ5LoJyK+Z2rjQj99o/ybjeR6k8XlHnpZ0zfEWDkKT9sPf5Q= Received: from BN0PR10MB5128.namprd10.prod.outlook.com (2603:10b6:408:117::24) by PH0PR10MB4679.namprd10.prod.outlook.com (2603:10b6:510:3c::15) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6631.42; Sun, 30 Jul 2023 16:55:42 +0000 Received: from BN0PR10MB5128.namprd10.prod.outlook.com ([fe80::2990:c166:9436:40e]) by BN0PR10MB5128.namprd10.prod.outlook.com ([fe80::2990:c166:9436:40e%6]) with mapi id 15.20.6631.042; Sun, 30 Jul 2023 16:55:42 +0000 Date: Sun, 30 Jul 2023 12:55:39 -0400 From: Chuck Lever To: Hugh Dickins Cc: NeilBrown , Chuck Lever , David Howells , Jeff Layton , Jens Axboe , Matthew Wilcox , linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] nfsd: Fix reading via splice Message-ID: References: <169054754615.3783.11682801287165281930.stgit@klimt.1015granger.net> <169058849828.32308.14965537137761913794@noble.neil.brown.name> <3082a8da-4a13-de28-ed50-8aa2e7a59afd@google.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3082a8da-4a13-de28-ed50-8aa2e7a59afd@google.com> X-ClientProxiedBy: CH0PR03CA0051.namprd03.prod.outlook.com (2603:10b6:610:b3::26) To BN0PR10MB5128.namprd10.prod.outlook.com (2603:10b6:408:117::24) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN0PR10MB5128:EE_|PH0PR10MB4679:EE_ X-MS-Office365-Filtering-Correlation-Id: 8d011b71-3135-46ca-c631-08db911dcf71 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 7yvUrOyZ1ntq/HvZMjYJmBYyIRfSEcXa0O9AMwthD0DSd8CG2zLvHb1MshsZDLolCh5wP0ZQ0FvyzWUpc5L20WD9dGRrewE7f0Gk8b5RqvzTMB5b44kuXAQ7fhHLugPobxfgRifRyuWK38ItLuRiU6BZjczTB+Jgljhf02sld8JNPYnxmbopSE/+MppAcVb4WQUX0QruVGtyChoMzN0ilCYY6pI8r1R1FE2OpLZkNJrlBs4i9SlDGfRH7gltAwY1xgkHT3W8e8BqbiU/fQKNfV5cCvdy/Bm7sQA2MQeWoCXpdlujWZw+ulFmd/mByphvXZCqg8Bfch+eh2aqE6eVIpnQf6FxZPKS8rR37KIPUCKXZ79xIWHX8YFeMnte0efmydymjmWZB0KQXeZCSCbRFqFGObT1JI0ge9cafDXhdC+1/swRXcg0/WCCPnui9cx5qW3BYj5+m18zg1IYG9Sn7S5bM6oERb2zfkFlR5gn3JYON96n6KyzmMD8C+IkriYEuatTg/QtQbPf4g/qqHBv0G7vsamP+kSm2qNg7xGBynK4K4vnn2/1kj5UL2pAWkR/ X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BN0PR10MB5128.namprd10.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230028)(366004)(136003)(396003)(39860400002)(346002)(376002)(451199021)(2906002)(5660300002)(7416002)(8676002)(8936002)(44832011)(316002)(4326008)(6916009)(66476007)(66556008)(66946007)(41300700001)(26005)(6506007)(186003)(38100700002)(83380400001)(9686003)(6486002)(6512007)(6666004)(478600001)(54906003)(86362001);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?0l5C2GtEcU11mu03OVLZRSnVCZ1WkKleUwbUexR5UYwl92SEqabGGne1eu+0?= =?us-ascii?Q?vwQg7gTcCNsZdI1pnUKySGqcUG+cOFxSPO1qud+/B7v6yUYhxdIhlDsn0Dv9?= =?us-ascii?Q?A/iLKWG8PLWTQa/Frn1CgIH9abt8dtY2lQ25FQJ6osKB9dM9nCThOt0/rg9y?= =?us-ascii?Q?d0YN8+8tiv8ckV7y4RdUS1k3cdoG9/9AwppeRNOIbrzqApjz1csXXd8tVVF+?= =?us-ascii?Q?1vZIBnc+N6dZOKZjJKxznt+HeyKTrxQVnHp+T3o1ERRZnw9eIneSnBCKrZzQ?= =?us-ascii?Q?N+yOaHcolXk+/RswRowD4X6PSTBATZb/Qi989nM+YzWW3zuZCEntc8Bfgcye?= =?us-ascii?Q?Fu191uYBM8BxBh8oPlFqKhVs1xteG2Dvkq4HmD6jFaZJ6lLSHT9fcHtZ6bOS?= =?us-ascii?Q?43sly8xGjUqgYJ6a09YI7prYv1n0WR2m4Ka7fw5NABwJJ99d4aDj+ypOv4/B?= =?us-ascii?Q?iSN3M2tmkijkY5r5ge2cxs08/bMhs/8ERnU9GnVT16Rm5J/owELuvtR++CAl?= =?us-ascii?Q?NiDxElUKWAbYSuiLO/1JmYHaR8D1jiYe1kWBTBbFAAZAyO2dFSG887coHB9c?= =?us-ascii?Q?o64/+rU52iDMn5oqm4dv8sGzYHlO1ThzkJ9vR2u8S9WCrST0ZQ/cZTX5QfUq?= =?us-ascii?Q?WtUjGaBGktm8DGr8WWmOUEJnRyc+7Jy5W7cgc8sAtskNfRVwMqdElZf6FVLA?= =?us-ascii?Q?1MJQemTX05qa0wzgD/hLy8vNPb59g/9CfKtT1iruPZCctQ/YSy5ooO9bl2V1?= =?us-ascii?Q?BhIJBitwii/lp2J6pbAoHkGhzhB/HhsnUfXFDkIADopzCnoo5hC+A8d9cUCP?= =?us-ascii?Q?5Wj/vIs3nDGEADKA3IXoBDfnZdzNljqBI5RNoADKgYm9TjV9Vxsk4043zA1d?= =?us-ascii?Q?bCeixaXOPPFs96h/em4xoBYmiBBWjSvbPUUJjcNDjqCGkNDLOqqFNO43c5mc?= =?us-ascii?Q?KzpRgcP7GkKJNNLxKbtVq0kYvytGH7I7jzIzUABlK/gAEKEfXqrXQXxVDLdG?= =?us-ascii?Q?TUYbu+ZCN26zNIwIl+ypy6Lg4dAcw3Tf0ULgdHCCvO0NEnTpJz+rmYY7stme?= =?us-ascii?Q?sXjKw3wKQCfMUezsjXIxyoe0Rw2thFtTD92UhwR1ZxCX6lUQb/C5oTujIgR7?= =?us-ascii?Q?GzbhSBPBkUjhvqHtWafYTZRBYGC2hdHQHIbw/ZTonu3KFGgdGt2RMxhgzK/Y?= =?us-ascii?Q?Q1s7SBsn/o5fBDHjFNqznNrIjXDCGR4YO3VCEjJ1HVijDt2J/xxfegYTh6gW?= =?us-ascii?Q?9Gp4BRKX90//rcrISoIO/Xczkb12ArAnxp6dzo+g6AB5DTRHN9G/QvSsGDb4?= =?us-ascii?Q?k4rBx6QzL8kTpDfaxxHBrK02eOOZJRLT2IKbs0MW7OdlUqEN3Y4h3Zm1iwL5?= =?us-ascii?Q?zqy36poZVKjFzM4KhB6TAlQb2Lclk1XkupROeUtSmVqkaB6nr7yvKRUU4CB/?= =?us-ascii?Q?s/0802YAYqD1kgyLRQncRlQ0lBd5a4UF38jGKnlma8b8lORw6SAknTdJMsyq?= =?us-ascii?Q?xofECbhJDOv15afwYjBVjms1DkDH4BCTbq619hXYsl67PiKnp8gbcHt6u4jR?= =?us-ascii?Q?069AwPXJn1LIj75O1iZj1dM8RGX6a8YOG16hR1hhZM5LkocSzztgjNVACzHh?= =?us-ascii?Q?yQ=3D=3D?= X-MS-Exchange-AntiSpam-ExternalHop-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-ExternalHop-MessageData-0: =?us-ascii?Q?QCHSe3paoOL9jKD+9GqqeYftecly04ASfjUwgdJXlUMJSTjVooVnQLfZ1RSd?= =?us-ascii?Q?YEjtCUINjexJc8vqxlvPe7T9EDCqpCpYGtTlQlYtXrAbgx3S9t1xKFIj6PI8?= =?us-ascii?Q?HzA9igM5tiBy33rEBE/DqR68m6C7ANwLasNazl0llQp/zjF1gB+nZ12SBk9m?= =?us-ascii?Q?9wYDCcFrSAwmmrdH9WE5Od+ipfeAyPha/tn0eH2wiLhdPUVPFiqkJE3NfZZC?= =?us-ascii?Q?B2mbrX/GbugGJzHhiaGIil56quRWewM4aULaEpI3jZvLE/eYkKi6vR+YdJwW?= =?us-ascii?Q?9uyV+sBZNhrosSYXSnCLCoJw7Nqzyhq3hOQmdE+1P0VUO/KOY9xBokKtQ4We?= =?us-ascii?Q?y7u0boGKg8W7AXm6zi680UTZkEXq+wPNXPHSTpvNY/dQEvIz12szZSgQNXaH?= =?us-ascii?Q?DVvh7HTP3CrILKj/eOhn5ZzYIahuDUOM6k+mIORTCd8SpRdp2OAJAs82hw9/?= =?us-ascii?Q?Xkm2rl6AAGBtsW3jUNnMQnFmANrpqTehfTb80bIIOqSzZ3Gf8ct1vwzXjfP/?= =?us-ascii?Q?pMRXrMngkL3FXq4+dOhat2lFAwIpu5lLFsR8F4nynF92BBpPG6mo+LH8Z/xg?= =?us-ascii?Q?YR+k7I44PqXFcriMQE2tLgaMOcS4kFt7M/tEEdfyVmNo7smKQDo7mc6U8F45?= =?us-ascii?Q?B2zD//T9UGtqkhugcQiHikoZ2/Zz69AMIorY1na6o2VON0xT1k6skZAG3wWY?= =?us-ascii?Q?38pNZPAoKcl6OowY9BpP3qK3ipo753ow5sO2jCH6Ar0LjDI6TWeSTWIMa/XS?= =?us-ascii?Q?KPyhz7C9041Kq9ztpfBrugmyt4L2DIsUW3+TYs+rSIrAFiEhdpeLIJtEoKOE?= =?us-ascii?Q?P1whhvieUprKS+FHtr8opLs69jiHBi+/iok11xO6DELzbwKdTCaNqPP+ZLTu?= =?us-ascii?Q?r6+LMBUkjHHWGsjNUMM2/Yq3AgUmZqX2+SKHXKL0SilO2Jsk6cXG1o+lsXaq?= =?us-ascii?Q?OhWhBgvnBI4f72RuA79DKg=3D=3D?= X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-Network-Message-Id: 8d011b71-3135-46ca-c631-08db911dcf71 X-MS-Exchange-CrossTenant-AuthSource: BN0PR10MB5128.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 Jul 2023 16:55:42.4826 (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: b1IHx3uWU3sMdv7CzoBz5cpUwlC9EDybnUg1Quo49LXfIZNU19KDoYW8Q8d5hxp6u1VDI5vYl850SFf5Z4pk4Q== X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR10MB4679 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.957,Hydra:6.0.591,FMLib:17.11.176.26 definitions=2023-07-27_10,2023-07-26_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 mlxlogscore=943 phishscore=0 mlxscore=0 adultscore=0 malwarescore=0 suspectscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2306200000 definitions=main-2307300156 X-Proofpoint-GUID: PuLXP-tAd48jHwPpgPSSM5k684fMvCeM X-Proofpoint-ORIG-GUID: PuLXP-tAd48jHwPpgPSSM5k684fMvCeM X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 721F94000A X-Stat-Signature: ds7bxxguuccjxym1bth5pu7r3f44ugxz X-Rspam-User: X-HE-Tag: 1690736157-738332 X-HE-Meta: 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 eec60IDf /hl18CX7HP1IdPv7XC7MnVR5HIWSEXiaTP0xb4F+lryBP8e7bmAZ3eC5SBViwpCa3WHEhM/CHvn4nvzJBJmQSHHbgtU/tccKF7SSnnQNcKsoFd3yhlzoVivyBJ2yVbloTHxwcpOeKwmlvA9DfkNJHXgPNfY4hE7+Nc9F1afDuDKGkl/Wos7g4JXAD5nKfQeP3vSez3sPFE3YShGFB3I27OLo3wKww1DiLMfjw8vNaw4roYJv76bUB4rxb0H1qSACjZC7LThNMdXKFET1sTuMnK6b/rOBIp3kpIiZ9hUU9xbRvf/0vDasLEN1EE3ekwpiOvMTq0fi1mnJo6BpneHsMCB+vqxA9xaNoP75eCboFD23KNzOzr+T2XDxLt3RkRwfN9AGm7FQCK2c7gX7jd6KmF7QN32bjXKHGd1tC 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: On Sun, Jul 30, 2023 at 09:50:44AM -0700, Hugh Dickins wrote: > On Sun, 30 Jul 2023, Chuck Lever wrote: > > On Sat, Jul 29, 2023 at 09:54:58AM +1000, NeilBrown wrote: > > > On Fri, 28 Jul 2023, Chuck Lever wrote: > > > > From: David Howells > ... > > - This fix is destined for 6.5-rc, which limits the amount of > > clean up and optimization we should be doing > > > > I'd like to apply David's fix as-is, unless it's truly broken or > > someone has a better quick solution. > > I certainly have no objection to you doing so; and think that you > and David will have a much better appreciation of the risks than me. > > But I ought to mention that this two-ZERO_PAGEs-in-a-row behaviour > was problematic for splice() in the past - see the comments on > ZERO_PAGE(0) and its alternative block in shmem_file_read_iter(). > 1bdec44b1eee ("tmpfs: fix regressions from wider use of ZERO_PAGE"): > ah, that came from a report by you too, xfstests on nfsd. Yes, I thought we had visited this ZERO_PAGE approach before, but couldn't put my finger on exactly when or where. > In principle there's a very simple (but inferior) solution at the > shmem end: for shmem_file_splice_read() to use SGP_CACHE (used when > faulting in a hole) instead of SGP_READ in its call to shmem_get_folio(). > (And delete all of shmem's splice_zeropage_into_pipe() code.) > > I say "in principle" because all David's testing has been with the > SGP_READ there, and perhaps there's some gotcha I'm overlooking which > would turn up when switching over to SGP_CACHE. And I say "inferior" > because that way entails allocating and zeroing pages for holes (which > page reclaim will then free later on if they remain clean). > > My vote would be for putting David's nfsd patch in for now, but > keeping an open mind as to whether the shmem end has to change, > if there might be further problems elsewhere than nfsd. I'm open to that. -- Chuck Lever