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 E7E41C433F5 for ; Fri, 22 Apr 2022 16:38:45 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id EFC906B0075; Fri, 22 Apr 2022 12:38:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EAB298D0002; Fri, 22 Apr 2022 12:38:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CFE1A6B0089; Fri, 22 Apr 2022 12:38:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.25]) by kanga.kvack.org (Postfix) with ESMTP id C2F2A6B0075 for ; Fri, 22 Apr 2022 12:38:44 -0400 (EDT) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 9378B24C2D for ; Fri, 22 Apr 2022 16:38:44 +0000 (UTC) X-FDA: 79385073768.14.9B02074 Received: from mx0b-00069f02.pphosted.com (mx0b-00069f02.pphosted.com [205.220.177.32]) by imf02.hostedemail.com (Postfix) with ESMTP id 5BB4280032 for ; Fri, 22 Apr 2022 16:38:42 +0000 (UTC) Received: from pps.filterd (m0246632.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 23MGb3tQ013493; Fri, 22 Apr 2022 16:38:40 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=message-id : date : subject : to : cc : references : from : in-reply-to : content-type : content-transfer-encoding : mime-version; s=corp-2021-07-09; bh=9Dh9m4dRXnjgFlbU+Vvi1NYJaq0yb86t6jHcYKItQsM=; b=aMBBR/ORybHCyxCVjt3oJdI12b1hc5YT5I7oxBgD03VGDftEbnz0HF3U1wpQe0TDOMPF 6GU9l5MO25Oa136HJcgHoPYTelShwYtTsnQfBL+MVnnboF1GLSmyxUHm0ikZBLHflQRz fSuhc3dnzTqpQ865K79qmFcg67II95msWDUUXpD+CFj6SIFTH6lMKNciyrOjCMYOGehr fW2+xouV0GfZZeRtEZ8gK7OxQuSa34jtenZtfVPeOdiZ8Iylfip9lB8WMODD+e1MIBDf 3LBHTtTupvyLVcClix4JNJ+kQEQ2ZuAlFGGhclKsCwupG0TYsCxu6swQwj8AVOM+hg3o 4Q== Received: from phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (phxpaimrmta01.appoci.oracle.com [138.1.114.2]) by mx0b-00069f02.pphosted.com with ESMTP id 3ffndtq8vw-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 22 Apr 2022 16:38:40 +0000 Received: from pps.filterd (phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com [127.0.0.1]) by phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (8.16.1.2/8.16.1.2) with SMTP id 23MGAKi3036754; Fri, 22 Apr 2022 16:38:39 GMT Received: from nam11-bn8-obe.outbound.protection.outlook.com (mail-bn8nam11lp2177.outbound.protection.outlook.com [104.47.58.177]) by phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com with ESMTP id 3ffm8dwpgs-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 22 Apr 2022 16:38:39 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=iYyKGyX02d0YL7ZU8BnszMt+QYFOh4L4PnVwLDpBXlfVmEAySXX6nqeFzSVwJU+RjEmkq5tztoDdpnLrc0PA8JJB3lGpMgp3U4bZTI5htYF/WeujqTicXlRb6hpx64bO9Uis0HYKFUwd5TLcvelRhaGCKRAE4F4Eo0/eoW3TvFlrqRzO1lghFbT2B9gLhefggSact9Immp3S0H387lEhzXxVnMCP5H0X0eTfhVh86I5yvem7+h4zM/k1idxCzeHCMVDlU+fraG/dluK1hGwh/qJAuNArw+dYbbyifwVookj8vIW2H/0NrPbpA/zEbTVmBcbPJZ1qnQq/u2RVWRoecQ== 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=9Dh9m4dRXnjgFlbU+Vvi1NYJaq0yb86t6jHcYKItQsM=; b=ftF/gr+Lbq0Qyy95PNJiTAkK47V9+G+DD0Kwe2yIWXJsToWp27UaM0ShfCnuNPQHCiZvEi0BidLX3yJn7hc2cZL7YFVp17Ns7b0VbWcpoiHDT0PduCB/7aqmLf77YaR3SbkNC8CR8vQhdTMw2jNXtfzeRiDQxqGRN2BzYX52R/211h4HoisUFFvAbI1zUgg35OMgDpTKEIYa6zTHHjxGPWTF3NeTu9gCJiZSRaOHKn4ecNQhCrtfz83P/lG2LpMVqDiHU+Ft9onKE+/hTlhNvf5uxQAS3sjy12eeFca/yxX8uM6NC2iUheaISf5ekx23fBSK+Sy/QHTxJWVOgyVY+Q== 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=9Dh9m4dRXnjgFlbU+Vvi1NYJaq0yb86t6jHcYKItQsM=; b=YOrLAPP1oN7fUMXpf25S0mQ22WgquR4fGBJOPfw5fB7auYYVqWpi4UciggqujMrHzBcbRf8So1RcYF53G38fNwuizrfClTVB472W6zBFpaV98iiUdj9+vGY8v6aBPK5uIrp5q8YvtoiEPwfhbHQ/eyGg0Z7reO/9NY8EDI2vfug= Received: from BY5PR10MB4196.namprd10.prod.outlook.com (2603:10b6:a03:20d::23) by BN0PR10MB5335.namprd10.prod.outlook.com (2603:10b6:408:127::23) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.5186.14; Fri, 22 Apr 2022 16:38:36 +0000 Received: from BY5PR10MB4196.namprd10.prod.outlook.com ([fe80::bd4a:8d2e:a938:56af]) by BY5PR10MB4196.namprd10.prod.outlook.com ([fe80::bd4a:8d2e:a938:56af%9]) with mapi id 15.20.5186.015; Fri, 22 Apr 2022 16:38:36 +0000 Message-ID: Date: Fri, 22 Apr 2022 09:38:33 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [RFC PATCH v2 0/6] hugetlb: Change huge pmd sharing synchronization again Content-Language: en-US To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Michal Hocko , Peter Xu , Naoya Horiguchi , David Hildenbrand , "Aneesh Kumar K . V" , Andrea Arcangeli , "Kirill A . Shutemov" , Davidlohr Bueso , Prakash Sangappa , James Houghton , Mina Almasry , Ray Fucillo , Andrew Morton References: <20220420223753.386645-1-mike.kravetz@oracle.com> From: Mike Kravetz In-Reply-To: <20220420223753.386645-1-mike.kravetz@oracle.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: MW4PR03CA0163.namprd03.prod.outlook.com (2603:10b6:303:8d::18) To BY5PR10MB4196.namprd10.prod.outlook.com (2603:10b6:a03:20d::23) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 8e71f5ad-1395-406f-7ed5-08da247e8c45 X-MS-TrafficTypeDiagnostic: BN0PR10MB5335:EE_ X-Microsoft-Antispam-PRVS: X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BY5PR10MB4196.namprd10.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230001)(366004)(6506007)(38350700002)(7416002)(38100700002)(52116002)(6666004)(53546011)(186003)(44832011)(6512007)(31686004)(26005)(36756003)(5660300002)(6486002)(508600001)(8936002)(66476007)(66946007)(66556008)(83380400001)(2616005)(2906002)(86362001)(316002)(31696002)(4326008)(54906003)(8676002)(14583001)(45980500001)(43740500002);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?cUlXZHlZQjRxbnZoampzRGYxS1praHFmYy8zTmFhczRId3p1dDNWNmNUK3Fx?= =?utf-8?B?MFdpM1oveThTQWdvR21sWW1ESllKNXhJTkJrS2hVbUdDY3pNZjJ3bCtxYzFC?= =?utf-8?B?YityV1k3YVlVMmQ0VTBwOXR5am1wM2xiRkgzeDl0WWw3bjYvV0h4UXRKZHVr?= =?utf-8?B?ZElDbUppZ1FuOEdvckNLcSs5YmpoSzVTaGJBMUpMaVIvWU1NRzFVU1dPd1Y3?= =?utf-8?B?QzlvcVh3bzhZVi9JbzRSOTBNT1dvK2szN0Znb0xmSU1sNUg3cWdxNG1wM0w2?= =?utf-8?B?OHM1dVZDeldUYUJHelgrRHNEYzdjTjVRZTFZbUVHdHBIOFdUYlErUngvU0lW?= =?utf-8?B?QTRGbkt4Q2FuUm5iWDF3dTlUWTNXSWpadkZ6aWFINzgxSjhtK1d6TUoyMmNV?= =?utf-8?B?QmxSOG1QK255WFZ4MkdXY2VMOFhxa1F6Wkk2VVl5YVFyaVVvc1JoRm93QUFJ?= =?utf-8?B?VDRtTWxJd2NjcGpxRzJnbHUyQUFEZ1VzVmtnZTdmTFBzMUNrR3hTdGoySk9z?= =?utf-8?B?NzlrSXJIOHBXZkhnQXpQaVZod1kwRUl5RDN2U0lFUzBKaWwrVkpqb1Bka1VY?= =?utf-8?B?d29JT2E3WW42K1NqQnFJbExvanpsN0tZalk0M0xBVk00MktSblQ1MjRKYlRI?= =?utf-8?B?M0FocUdUMng2MVFpbGdWUlQxMnhHWk11V212Zm5xSGM4aDRqTHo3UUNkUS9Z?= =?utf-8?B?VGowaWtha2R4M3F2M0lid3JVa1RUaHpzYnVDYVMvVVdYYjhLa2tqZjVlNXZ0?= =?utf-8?B?dThZQ2oyNFhyV2IyblZRMUwzMWVOS3FXV2JuemtYVFloNHJueW1Eb2MvL0xV?= =?utf-8?B?RVk1NUtyOUsxOXlMblZheS82dzh4UElxTWVzbnBTWTBHZFAwM2YxWHBVWHp0?= =?utf-8?B?NTlISkQ2M3NmSmU0YXFFd1BadWc2WjR2QnI0OHIrTGJidTEvR1dhOU1XeXRQ?= =?utf-8?B?MGdqaDBSTTBIQ2lHaFA2eUgyNWg0M0VqM3o0dkc1NXMvQ2Z6QWJCajQ3OG5X?= =?utf-8?B?dlV6Yll5STlhY0VMdjRJU216L3lJdXVzN0xiRlFOc3ZoM3RwWGRJQU5RemVC?= =?utf-8?B?SzNmNGQ4bGpGS01Lbm9heEczQ2U5N0thL29BVVRtd2NXR20xVyt1RWxaTjJB?= =?utf-8?B?cGFIaUVGdjRqaUNheTJ6QnRHTFJrQTZ4ZlI4NDcvK1NXc0E0anozTTI1R3g3?= =?utf-8?B?NnFBU2MzeFNJMWYwM1hHdjdtWUdHeEc0NTUrcXVVbUQxQVU4akIyalI3VEtV?= =?utf-8?B?RkZIUkRwTWJmNFprOThJSWNUaWwxTGREVm5JZWYzbS9kVkFTenBRUExBMW1u?= =?utf-8?B?bmY4M1pBR1VsanE0alpXOCtEUUlJMWd0Vnc0UWNnVnFhMTJCMDlvWnhSUS8r?= =?utf-8?B?UTlsM2xIaisyUENVMmU2YWNrL0F1YWZ1QlM5ZDFyOUxTRGlPRWVTYjhRVU52?= =?utf-8?B?bE9SY1VMRXFKaTBKRWRHcmUrUTVLdUprNS9MNm9kTHFiMk16WHZYMU5xNytP?= =?utf-8?B?Q25jRVZGeEhhaXVjSEFsbnpFUEZOYmQxZm9EaXQ4U1lHUGVkaU5jUGhHbEdm?= =?utf-8?B?d0tJTHY1TXNkT3BmOVFrblV5byszNHVnWEU3TFNCVlN3TVBIQnJhend2UFk3?= =?utf-8?B?aDBWOVBOcDlVT0NaeFZLd3dLZ2x2ZWR1eUNqZGU2RlZTUjkrNWFWZG1waGt4?= =?utf-8?B?YnhudmNwNkRCMWdiT0YyN0xpV3dqZ1BUZi9HWGphRDdqTWhHS2xaZnJVd29D?= =?utf-8?B?L3p2QTM2V2xYUVM0cXppcGJJbFFDZ0lGL2VOMWcyam54OXpqR2JwUFZNZkkz?= =?utf-8?B?cjR6VWZVMHlBcEMxSFdlTGxjWkVBVjN4VnZCaDF1RlZPRXI1WCt6NXE3SEhH?= =?utf-8?B?bm5Jb0doeGlNVW02TlZLRDJMTEg4Vnh2QytSaW0rRnF2NDVGRWpxQUlKa2NH?= =?utf-8?B?Z1N5QmZBMEJ0eEJXd2gzTXJKMFBRMXhXMFgwdm5JeG14MjF4Zko0U3pnVEp3?= =?utf-8?B?QjVFZjg3c1pVa3IwZTMwTHhwR0s4Y0E2OTd6MWh4R0ZDejZiQXlEK0RFK09x?= =?utf-8?B?alBCOXpNT01wdFpmNEJndlJOc0xOeG1lckFSRDdHVEVZdCtMUUdDQnNDeGpC?= =?utf-8?B?K0dkWUF2N1BMM1FuY3crTmdwOTRUdjVCVHRtMzN4ZWljQmFmN3BBaVJQL1cy?= =?utf-8?B?UXZOeUtWSFJoNFlNSW9XYWR3Mm10WTFvSTBnMmNsOTk4N1hHaWxHR0N3ZHdN?= =?utf-8?B?YU5TWm9ISjdsT0h5RXowS0pnK01CSEFJclJlMUpBMm9CdUordlp4ZGtTSFFt?= =?utf-8?B?eko2V0s4T2NCci95azFNNXR0cWJ4RmVWZ1hkV3E1UGxaQnIvdDBXNmRsRjJV?= =?utf-8?Q?CFxTo9t2NA54fOLI=3D?= X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-Network-Message-Id: 8e71f5ad-1395-406f-7ed5-08da247e8c45 X-MS-Exchange-CrossTenant-AuthSource: BY5PR10MB4196.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Apr 2022 16:38:36.6377 (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: RmxdW0leQgmMtOJ9U13XHO0w3Uo7ezwotmt9Vxpzl16th7PAb7NWbsNSeHm5a2gJAKhQ327+T3QXKTGtWBtB/w== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN0PR10MB5335 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.486,18.0.858 definitions=2022-04-22_04:2022-04-22,2022-04-22 signatures=0 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 phishscore=0 adultscore=0 malwarescore=0 mlxlogscore=920 suspectscore=0 spamscore=0 bulkscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2202240000 definitions=main-2204220072 X-Proofpoint-ORIG-GUID: kVpScXRzhvzQIMtyscnYSqm8IICyweBQ X-Proofpoint-GUID: kVpScXRzhvzQIMtyscnYSqm8IICyweBQ X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 5BB4280032 X-Stat-Signature: u1jthoka48gqj49o1ojre5e7o7pscdi7 Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=oracle.com header.s=corp-2021-07-09 header.b="aMBBR/OR"; dkim=pass header.d=oracle.onmicrosoft.com header.s=selector2-oracle-onmicrosoft-com header.b=YOrLAPP1; spf=none (imf02.hostedemail.com: domain of mike.kravetz@oracle.com has no SPF policy when checking 205.220.177.32) smtp.mailfrom=mike.kravetz@oracle.com; dmarc=pass (policy=none) header.from=oracle.com X-HE-Tag: 1650645522-193065 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 4/20/22 15:37, Mike Kravetz wrote: > > Patch 5 in this series makes basic changes to page table locking for > hugetlb mappings. Currently code uses (split) pmd locks for hugetlb > mappings if page size is PMD_SIZE. A pointer to the pmd is required > to find the page struct containing the lock. However, with pmd sharing > the pmd pointer is not stable until we hold the pmd lock. To solve > this chicken/egg problem, we use the page_table_lock in mm_struct if > the pmd pointer is associated with a mapping where pmd sharing is > possible. A study of the performance implications of this change still > needs to be performed. Sorry, this approach is totally wrong!!! If sharing pmds, we MUST use the pmd specific lock as that is common between processes. If we use the process specific lock in mm_struct we are not synchronizing pmd updates between processes. I am going to rethink the idea of a vma (process) specific synchronization mechanism for pmd sharing. I abandoned this early because of some lock ordering issues, but think there may already exist code to handle situations where we run into trouble with lock order. -- Mike Kravetz