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 7F9B6C433EF for ; Mon, 29 Nov 2021 22:09:23 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0DE746B006C; Mon, 29 Nov 2021 17:09:13 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 08E626B0072; Mon, 29 Nov 2021 17:09:13 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E235F6B0073; Mon, 29 Nov 2021 17:09:12 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0060.hostedemail.com [216.40.44.60]) by kanga.kvack.org (Postfix) with ESMTP id D4C5A6B006C for ; Mon, 29 Nov 2021 17:09:12 -0500 (EST) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id A57708A3E4 for ; Mon, 29 Nov 2021 22:09:02 +0000 (UTC) X-FDA: 78863358924.20.FC302D7 Received: from NAM02-DM3-obe.outbound.protection.outlook.com (mail-dm3nam07on2085.outbound.protection.outlook.com [40.107.95.85]) by imf07.hostedemail.com (Postfix) with ESMTP id 5316F10001C6 for ; Mon, 29 Nov 2021 22:08:57 +0000 (UTC) ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=RIMOJQ3k/Jx3Gxb3BcTDYTqrojjKOBTI2EanJFhZYLwcAFHcBotXaa4KpJVuzHwWcJcGRstkOuA971n6UoMv1D5Y/B7HrPAQ31hpdBOMkKzSz4k8CGw0tgXPOHsXZjxeRxz3uziaDKcFmn82BtR6qgs4jfQqQsxF78JNTp4NlABCUQeSIvvrBuBpLwKtiJlYnU9OxqwbljD/bmS5a5efCCU7lKQjYdHonjnmWZcEc7WvK7K27OFgQc5dkl+zbAk/3P6DWEyTo1evwtAMPjbR3nLPZyJb+lzmGDd7lZnWUeDeJX5rSm+GAV7WUJF28kXj77tiZ2XHChGwzfXrp7k3zQ== 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=8zwazSGCLjIMi3AqEDquB0s4llI/Xb/R+68c/to+kpI=; b=ayq0DxD8Dv30VnBSeHTtN7iZbEjtTI/etuWBYDDQx8tuzdHOiLDOgUZNwOE5eq5ilLcgb2kNZ9cch+6TkOTGIwyQGXlhfNjSvFnypRXp/vxcIIVjCzjhc+7epcoKzIcZnZ9q6KKHVos92WvEi4s6LcQQrVXOx1PD5+0B4kk3OfR2Wmy6ZISxeE2IHKPyQ3gKQM97LkA6JtcAgflwX3y4s4HWNO4HSyv75wp0BjD6dvb25C04N3PUYCKxrUHrJCCDKBw8mOg+oNqU3yNev3IrPwkcpOVzxQWNG8zFF14B+wGYXPI5UFEqfq/i4FHZAJKAGkboduEHSRbx8t+Ckng+XQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=nvidia.com; dmarc=pass action=none header.from=nvidia.com; dkim=pass header.d=nvidia.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=8zwazSGCLjIMi3AqEDquB0s4llI/Xb/R+68c/to+kpI=; b=Fib1Lp1xkXUoDEg/NZZGQY7j9UHkpiOgKfx6OaQI5H2AjwPYIizmwvSU1DYRIV7vCkw5uYHoXPxtGC7LJltvOUV6I02kl5VgE0owp4/YcpfXxlfb8jVu8n+iiDOuphmoA7RrBF26i/l13hKevhsQYW1cmqz2Jdh2GmqOJI/hr1kPQ0Sz0txXoVN09sJnlqU/Wxe1/NdlVNU7Co6++JS3F5Ip0ZDJYtO88gB+I29qJ5DN2jZfaChg/OzVVt8Ai3lsbdlvCrNLrKzh/hXpOS/RgthS5jKLywi2yGNtKpXxDOFd1wL6Dwkt9fGW++8i14XLmRsjS3nl4Ndcu2uqFGMTVw== Received: from MN2PR12MB3823.namprd12.prod.outlook.com (2603:10b6:208:168::26) by MN2PR12MB3983.namprd12.prod.outlook.com (2603:10b6:208:169::20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4734.23; Mon, 29 Nov 2021 22:09:00 +0000 Received: from MN2PR12MB3823.namprd12.prod.outlook.com ([fe80::2dea:e478:592:6d66]) by MN2PR12MB3823.namprd12.prod.outlook.com ([fe80::2dea:e478:592:6d66%3]) with mapi id 15.20.4734.024; Mon, 29 Nov 2021 22:09:00 +0000 From: Zi Yan To: Vlastimil Babka Cc: David Hildenbrand , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Michael Ellerman , Christoph Hellwig , Marek Szyprowski , Robin Murphy , linuxppc-dev@lists.ozlabs.org, virtualization@lists.linux-foundation.org, iommu@lists.linux-foundation.org Subject: Re: [RFC PATCH 0/3] Use pageblock_order for cma and alloc_contig_range alignment. Date: Mon, 29 Nov 2021 17:08:57 -0500 X-Mailer: MailMate (1.14r5850) Message-ID: <35A20739-152A-450E-8535-2236D2B28748@nvidia.com> In-Reply-To: <52dbf824-76be-cc34-3983-d45510b1b618@suse.cz> References: <20211115193725.737539-1-zi.yan@sent.com> <3083463d-978b-fbe6-dadf-670d400ed437@suse.cz> <52dbf824-76be-cc34-3983-d45510b1b618@suse.cz> Content-Type: multipart/signed; boundary="=_MailMate_4B5044BF-6C2C-47FF-8D31-06E6118699F1_="; micalg=pgp-sha512; protocol="application/pgp-signature" X-ClientProxiedBy: BL1PR13CA0184.namprd13.prod.outlook.com (2603:10b6:208:2be::9) To MN2PR12MB3823.namprd12.prod.outlook.com (2603:10b6:208:168::26) MIME-Version: 1.0 Received: from [10.2.82.121] (130.44.175.231) by BL1PR13CA0184.namprd13.prod.outlook.com (2603:10b6:208:2be::9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4755.8 via Frontend Transport; Mon, 29 Nov 2021 22:08:59 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: ef4ec0ce-0b24-40a2-1f6d-08d9b384d85f X-MS-TrafficTypeDiagnostic: MN2PR12MB3983: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:10000; 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:MN2PR12MB3823.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(4636009)(366004)(6486002)(16576012)(26005)(2616005)(6916009)(38100700002)(8936002)(53546011)(54906003)(36756003)(2906002)(66946007)(66556008)(956004)(186003)(316002)(83380400001)(33656002)(508600001)(86362001)(8676002)(4326008)(235185007)(5660300002)(21480400003)(66476007)(7416002)(45980500001)(72826004);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?KFivDfphpzyNfU4JRr13Xl4z6stZwmv+etn9zR/VX9AHy+HXuyQaG85Lm0Z0?= =?us-ascii?Q?zaz0TK6n3ZNT0hUVUDL0F29Lpn4z8VsmYdfx8UaQTn8kKu3Xx4K5zs9G/wgs?= =?us-ascii?Q?/DNDUSSQzNvvSGYsVq1L/7nrrpuimkZawcAJIlU6kM15/Xir2tDnqnlC9jgW?= =?us-ascii?Q?bNH6MHIiLYovMNpbHPWISng/f7zro6FTjrGHNWXxSz209zhn5MCkwyewwW6V?= =?us-ascii?Q?zoO4DM3UnyQNurmHgIjHl48ZPw2FcrxQ68/OmgS0jkiaDrfAQhF+gYjF1552?= =?us-ascii?Q?MvJ2Afp22509JAJlkObLJWCUjNlRY75X/cHlde9MtwNU0jkvbWIO6w5aeFDG?= =?us-ascii?Q?7s7aYnILH8DRDb35Wa3uNTTM9dKGOwJ94oTPqU2N5eMsRIWMrVImo3tk9Qt9?= =?us-ascii?Q?Ec1ssTMBM810nywI89apRMSUaR6sCIbCuPoHPxmspC4zES0J74h+GoO023du?= =?us-ascii?Q?M+Nw8rLSBVIFJNwU3vBkj7uKoAmUfRmNaOFML1vVY1YX8wU4DgLf+U6bk8a7?= =?us-ascii?Q?aw1aU8346oej/l5U36J569jKFGo7RlQNNWsNEKGfyqH9a91qLa5SV4scpSyT?= =?us-ascii?Q?0dbVykBlOnFjapTR3njXrWCRytVVEtIC41bjnRViXf2TLW7Gp1RC/eYljVJU?= =?us-ascii?Q?TUOrlUvn+haZYuMoiEcL7ctUoVizSG7BPeKEHG2WxKgom4hJYsnoR4CId2Pg?= =?us-ascii?Q?xAbenPwTPh7qG2A0mdCidff7kXsUhSg6OMuM1Yg/D0P4MWFB3PeRrCgFO/HF?= =?us-ascii?Q?5lLve2Eg7nyJL05o/8nmsQIcdc9mYiCLwJQNUuAwbhdCulaA6/Ogjw4dCBQv?= =?us-ascii?Q?3Zy2atXdf1fa8QJIITfOFYpn/d12NvcBBHCqgHE5x4GXqnR7x4+KXnsKx0FF?= =?us-ascii?Q?XvhcpvJ4IdQY8bVrK8tIlVT/yA9zfrIj19sCFTbPsRjYjdDoDc5t48PEm5KT?= =?us-ascii?Q?W80YawPwkRR9/8E+oTCU/ReFKqcjYeZfSXTb429uJ1Q7GtaokDxfIFcMq2Qe?= =?us-ascii?Q?3n2oKRyFhRYQwKuzgnL2xCSXK4QWEfTHCCjK+GKXcGlJcA5qNAMIwnSphnO6?= =?us-ascii?Q?Z8xdP3BbNTROvR2aTQHNKJ9HG438qt92g9luhP5+ZaDf4WfEXXc1eUgQlEnb?= =?us-ascii?Q?WfMdz7qgIAGByJXYJDEV1K5VX71F3kzXIAI6IN3qKxdjuZ8mUbukqRGpiB4I?= =?us-ascii?Q?junhmqzrg4nd4tF2E2kSDLVBZOfWtl1Od/gyrdUaIgS5+WJiYdDse0JvCjrC?= =?us-ascii?Q?YMZm8mYY78GgiGCtefkdnEU56fpPwrGH7zdd3AjpAA+Dkho1E/O4b7XKLAo+?= =?us-ascii?Q?03OF/sFRkK1eZ59/Ykgz+V2xbKlNVCiTs/7tKfI3XMz+iP1NBm/vp8I4A8Er?= =?us-ascii?Q?OmixYvP1v0g0kewwxE/IzYYNerx3N1Hy39HJjLoeYHgwAfd8z15I2l787fAd?= =?us-ascii?Q?qMc9XIGCZP1p7AhjRYL7Y+8f1/jt6Lqnhw5c12zHryug3PrzTQlo3m8TkXG6?= =?us-ascii?Q?kfQiQIv2GzeFce4UrqAEqgY4o117xP8EjqaZpxRJrR+yBMwrpMioAav0NeMU?= =?us-ascii?Q?katquDJ7xfSOGzK9/Hk=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: ef4ec0ce-0b24-40a2-1f6d-08d9b384d85f X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB3823.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 Nov 2021 22:09:00.0281 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: bklzwKCTclG+BWxJtbSwfaiA+ZwNF6OMSsZAkkBQ+FsXwnTcNz7Zf6S3SJ1zlbY5 X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB3983 X-Rspamd-Queue-Id: 5316F10001C6 X-Stat-Signature: c5z3dysc5c45og11rqtrdapm3jzd6m3m Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=Fib1Lp1x; dmarc=pass (policy=quarantine) header.from=nvidia.com; spf=none (imf07.hostedemail.com: domain of ziy@nvidia.com has no SPF policy when checking 40.107.95.85) smtp.mailfrom=ziy@nvidia.com X-Rspamd-Server: rspam02 X-HE-Tag: 1638223737-525419 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: --=_MailMate_4B5044BF-6C2C-47FF-8D31-06E6118699F1_= Content-Type: text/plain On 23 Nov 2021, at 12:32, Vlastimil Babka wrote: > On 11/23/21 17:35, Zi Yan wrote: >> On 19 Nov 2021, at 10:15, Zi Yan wrote: >>>>> From what my understanding, cma required alignment of >>>>> max(MAX_ORDER - 1, pageblock_order), because when MIGRATE_CMA was introduced, >>>>> __free_one_page() does not prevent merging two different pageblocks, when >>>>> MAX_ORDER - 1 > pageblock_order. But current __free_one_page() implementation >>>>> does prevent that. >>>> >>>> But it does prevent that only for isolated pageblock, not CMA, and yout >>>> patchset doesn't seem to expand that to CMA? Or am I missing something. >>> >>> Yeah, you are right. Originally, I thought preventing merging isolated pageblock >>> with other types of pageblocks is sufficient, since MIGRATE_CMA is always >>> converted from MIGRATE_ISOLATE. But that is not true. I will rework the code. >>> Thanks for pointing this out. >>> >> >> I find that two pageblocks with different migratetypes, like MIGRATE_RECLAIMABLE >> and MIGRATE_MOVABLE can be merged into a single free page after I checked >> __free_one_page() in detail and printed pageblock information during buddy page >> merging. > > Yes, that can happen. > > I am not sure what consequence it will cause. Do you have any idea? > > For MIGRATE_RECLAIMABLE or MIGRATE_MOVABLE or even MIGRATE_UNMOVABLE it's > absolutely fine. As long as these pageblocks are fully free (and they are if > it's a single free page spanning 2 pageblocks), they can be of any of these > type, as they can be reused as needed without causing fragmentation. > > But in case of MIGRATE_CMA and MIGRATE_ISOLATE, uncontrolled merging would > break the specifics of those types. That's why the code is careful for > MIGRATE_ISOLATE, and MIGRATE_CMA was until now done in MAX_ORDER granularity. Thanks for the explanation. Basically migratetypes that can fall back to each other can be merged into a single free page, right? How about MIGRATE_HIGHATOMIC? It should not be merged with other migratetypes from my understanding. -- Best Regards, Yan, Zi --=_MailMate_4B5044BF-6C2C-47FF-8D31-06E6118699F1_= Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQJDBAEBCgAtFiEEh7yFAW3gwjwQ4C9anbJR82th+ooFAmGlT3kPHHppeUBudmlk aWEuY29tAAoJEJ2yUfNrYfqK0ToP/3xsHoF15mPR7E4A+wmWq5NufZnqLsDp/BYx fTspt0RwFFCCYfGmltjtvaR3oJ6ZR/Zq4VGAH4bQqhV3RXW3ln+J10tGEr2P2/c3 jkSlXj4buDI+7M310afqzeTgp4OKZ2Bl5cEg2VcgGfSi4peM3ndSzc/MFwOzh3vH L7ObLigzaUvuJbD3Rp6xq3GDj+53JUZh8wkjZuRlX2RsGVu/tjS2Or+jtP7+wL50 WkcsyrEfOR8I7C92uArBGifAJQEP9jevsnwN6GJwI/ZEmga0djUBOL5AZcS2HEd4 ikd9vESjZNs7WSO2j7Y84LhPojaHA5v1xlkoNOdTbw3ndg/LP4nwlAMqs6/2fP3Q 7gmDAfOW8iZ9r9inH0HNFn0O+vtc+2X2TCgU0FPjv6osUzRc9SXJmTASPmwAa38C SUol5lwxsl78vG+A0knxOyusiK1Mb5iouJy/hPmuteobiCXS5PGe4ZL7WAm0Qv0U VdCBpuxcoB0GahO9KXWBuQ7EqCo2ubYKvsKQBeyByScKecbuKc55KMIUROPWONiB 7jsNUrZ++nQzRQ176Az5Ig69f09f6e4BnphGCkLhhEvmJUu7MDbQT4NPEOjippHY MbAnuKkUDEF8xY904hlNFcDetthF+ARWVNlx8qWBKqSzfVDodRwNqNBsqoMs1X8o /QiCLa1r =neNK -----END PGP SIGNATURE----- --=_MailMate_4B5044BF-6C2C-47FF-8D31-06E6118699F1_=--