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 939DCC19F32 for ; Wed, 5 Mar 2025 21:08:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 25A47280005; Wed, 5 Mar 2025 16:08:16 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 208C1280003; Wed, 5 Mar 2025 16:08:16 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 05CEA280005; Wed, 5 Mar 2025 16:08:16 -0500 (EST) 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 D5EE4280003 for ; Wed, 5 Mar 2025 16:08:15 -0500 (EST) Received: from smtpin09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 44650120B66 for ; Wed, 5 Mar 2025 21:08:16 +0000 (UTC) X-FDA: 83188735392.09.6197A74 Received: from NAM04-DM6-obe.outbound.protection.outlook.com (mail-dm6nam04on2048.outbound.protection.outlook.com [40.107.102.48]) by imf19.hostedemail.com (Postfix) with ESMTP id 7916E1A000B for ; Wed, 5 Mar 2025 21:08:13 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=s5OpZnv9; spf=pass (imf19.hostedemail.com: domain of ziy@nvidia.com designates 40.107.102.48 as permitted sender) smtp.mailfrom=ziy@nvidia.com; arc=pass ("microsoft.com:s=arcselector10001:i=1"); dmarc=pass (policy=reject) header.from=nvidia.com ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1741208893; 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=fFuSZXbmc8APE4wrOzdBdMzELWP5V2p3sNY3S4ztZHw=; b=AcxvsvBtJCBU9xyOpwThAbRXkdJSRrdY5rBySPbgHIkn80+6CUDtux7oGsX7vChikqacoM XzfAZ3pv9Lpi1GLhkWmhATkMqczlnEfTGtM7IHLMijdwRZjaXhAV1oQeOjF2XwzH3DtY3O Ho/yblMFR+75KcMBikSSlPjXAERa+cs= ARC-Authentication-Results: i=2; imf19.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=s5OpZnv9; spf=pass (imf19.hostedemail.com: domain of ziy@nvidia.com designates 40.107.102.48 as permitted sender) smtp.mailfrom=ziy@nvidia.com; arc=pass ("microsoft.com:s=arcselector10001:i=1"); dmarc=pass (policy=reject) header.from=nvidia.com ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1741208893; a=rsa-sha256; cv=pass; b=LDp8z8yG5yOHyVp6dhPcinTiOnsPbY9wwzRUCZMNBQeXMSqUT//Xg2CXeOE7PwO+4d9/qj swjZ8kJhJ3QnPgeR9AzFHhDfOvkXze0wgoVrtfpEVYTW6YjYOYSLeSq7xNvYR/mkK2rtiL dNkyLCVZT3BUBrvLduj15BQ4hM2++Lk= ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=vEdgB6azp5IZiWeGV46m61q77FcU1nmfCXJffjT+vYCBZjcVLwEqfrrDCkR7Zvn0BZ1FISO6PibM1Gs8NG/VaOTf2qOQadXbwNxt5t8j9EWbWEgaE3mMxq4QmAIf332kNW0GkjOqcdoq34usxVjX7KZrHWgW3ZWNarXNXahTysx2JqmNVpiHnk3ELsjntr/88oz012ybv4EXNEz1WpXo0yKjz5O0uh0LtO4QZQM1h/EKdnr8vvnzCFwJalmhSw3McQaFRqwDwCpczYNSerewZ4CMpgR+qZJ2WkZN3ggVGGnVPjPvy3hLb9Wsq3PEFWYlvg5HvVQtKRSc8jf9tC3VTA== 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=fFuSZXbmc8APE4wrOzdBdMzELWP5V2p3sNY3S4ztZHw=; b=Zduwb6qmhYq05vsrLVyaPvEIBHz+M7zp/PElAQIFyDS8DrO+E6KRXn54B4GDHd9YtaZtWZymzZFEVzcivWItBgRL3SAMiCCrKdPncTIIEuJpl0dI7kjdsQwpbpBuVNudRWqptZ/5IW8hTseeIWwTlmvC3gguCddwNyJPFNb6k8MVLviJ3K9rCEJefqdQOTklk3pjlYku2cL5camMGvqc7e1YpYjbw+s2X3Rsi+761fwZ0EfbwF+d42F7ZYyPdn2TZLEPlFImOaVBHX0qdLeWkcZnWbLF65hT6I8p/tPAjzeh9d/t+pYQOOQaLn/txn5+S6noRNHJmAKdaiiEidIzfA== 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=fFuSZXbmc8APE4wrOzdBdMzELWP5V2p3sNY3S4ztZHw=; b=s5OpZnv9q1EcJ7PVnXdRjnb7sA5AAwSFN9zRx7SBhen6I1m27fozblgUHuNo2Ikj75iFK+VHdDqr+aJ7HicCSqxbGSaeiYN9Nkg6LVAlNBKHL6q51ZOc1EDmd9w7WFbaigQcl2Jhk8x+DDXVmnQj9POinnxhiaY9CJiYclXhOnX8lLwbV8nS7/hOEO7BZ0Uhsy17RdU88S80j0nkpxHTGbmhlgXS7vGS/1MVPflsusBaQ5jDr7E3PKk/F5CILR8m4SW6Rav7NgooWL5VLVlNVTX2tmH2perjy/dPtIMstF6xt+i1PNM9IY6x1IJkLdEwhm8drI8xffQ22aKcmE6uXQ== Received: from DS7PR12MB9473.namprd12.prod.outlook.com (2603:10b6:8:252::5) by SA1PR12MB6971.namprd12.prod.outlook.com (2603:10b6:806:24e::18) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8511.17; Wed, 5 Mar 2025 21:08:09 +0000 Received: from DS7PR12MB9473.namprd12.prod.outlook.com ([fe80::5189:ecec:d84a:133a]) by DS7PR12MB9473.namprd12.prod.outlook.com ([fe80::5189:ecec:d84a:133a%5]) with mapi id 15.20.8511.017; Wed, 5 Mar 2025 21:08:09 +0000 From: Zi Yan To: Hugh Dickins Cc: linux-mm@kvack.org, Andrew Morton , "Kirill A . Shutemov" , "Matthew Wilcox (Oracle)" , Ryan Roberts , David Hildenbrand , Yang Shi , Miaohe Lin , Kefeng Wang , Yu Zhao , John Hubbard , Baolin Wang , linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Kairui Song , Liu Shixin Subject: Re: [PATCH v9 2/8] mm/huge_memory: add two new (not yet used) functions for folio_split() Date: Wed, 05 Mar 2025 16:08:04 -0500 X-Mailer: MailMate (2.0r6233) Message-ID: <43642DB0-17E5-4B3E-9095-665806FE38C5@nvidia.com> In-Reply-To: <238c28cb-ce1c-40f5-ec9e-82c5312f0947@google.com> References: <20250226210032.2044041-1-ziy@nvidia.com> <20250226210032.2044041-3-ziy@nvidia.com> <2fae27fe-6e2e-3587-4b68-072118d80cf8@google.com> <238c28cb-ce1c-40f5-ec9e-82c5312f0947@google.com> Content-Type: text/plain X-ClientProxiedBy: PH7P221CA0016.NAMP221.PROD.OUTLOOK.COM (2603:10b6:510:32a::20) To DS7PR12MB9473.namprd12.prod.outlook.com (2603:10b6:8:252::5) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS7PR12MB9473:EE_|SA1PR12MB6971:EE_ X-MS-Office365-Filtering-Correlation-Id: b8c08d10-85ca-49b4-fc0e-08dd5c29d4b4 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|366016|7416014|376014; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?QQ5TKV7cwWSC/R0rckTBReA2yy6eWH2iyRC28D0PadxdF23nH7kTlqOotfKq?= =?us-ascii?Q?Lqr248zHAW9/ugM7UskE7Jtbk9AyeAXHlekm2r08XPsDT7hKcrlMaxJWQg+9?= =?us-ascii?Q?pwEd0Qjch2diGZQwXY1oVNnQkwbCIj0JzkKhAFBJqbrUlXSpn02t9pbHoohh?= =?us-ascii?Q?6BRMm4V3CDULYzAiVm2vDkcC7YPXP2pENG241OVz90wJ0IjkItAPsNIbGwrM?= =?us-ascii?Q?5vLb/t0Rt732CUtIqIWmI/u7Bgc0JSiVf579wiSgQ9W++J/RYWfd1uKOE89g?= =?us-ascii?Q?DmY1SNo7WP1NaENJ+xA3X7B15ItWlf4MyGbGZJlfz4QDRJg9ZBTbizjjFFB4?= =?us-ascii?Q?DFUK32Gj1w0F5SXTgyulQDRUJ4xl3vZMYhMPm2dxNNfwm6FFb0Z4W+UIxogB?= =?us-ascii?Q?u0DT2bpgaKe0+etz2dxR1Lmh5fVI0JXJigoakLCLfwd2yUj5F52Toxg+mHno?= =?us-ascii?Q?PFOju9wgDVqIyuujBbU1jsm547yW22t4TECCVGPWbdmLy1+KRp9ZUV1QnOzt?= =?us-ascii?Q?FnS6FEPu7d4qIDJ59Q+OmAOTpkSEX/RzQeZwwLQiq1tZDPGKIPcJ9zAAMRW5?= =?us-ascii?Q?iKGaK2bir0xQp9ZzpZNcTZv6TZqHJukQ05/w+JlNcjxy5Yyy1ZYWxznHMgPb?= =?us-ascii?Q?9y4afh4JH1dY9XjDporfYLuBnz2D4FwpqBkKeZbT3w4VGBrw5uX9ZjSe9/rJ?= =?us-ascii?Q?mtRDSwqx98kSxFQbIlam1ywdS3DeDp0PncmeLOEy/R203IWC+1MaHA19vuSK?= =?us-ascii?Q?AtI+3CkQSXOLRAWab/n7JccEyTl7s4BvrdEcTMbWEiKCMu/w92PryoM0o0mz?= =?us-ascii?Q?Ri0sbza1Hkde9Ho2RS+7Tpja5WpEeuaXid4C5iAGog/mtxdrwrzedhbqV8Il?= =?us-ascii?Q?leB2kMtaFE7rHdS8QYQXOtcyXz+V7FdzPpjXZ7yrRWAydNw2/Tp5C3bumNHP?= =?us-ascii?Q?Mbs4L0ZEgF0LyqNh3FDSysX7EsI06fXmbVbcsbm/EJRMKnnxtSn68zG3fdpd?= =?us-ascii?Q?1LFiQX6ebbZoF/U+fI851uPWP5L/4Rc7PR0qHcuS12/pcT93+yJSEbd4p3w7?= =?us-ascii?Q?1mShUPBOSihpRJq/KxEjbrITPee5jbFDykm5xD9jDKLY5DRsxUmbE+OHpdZs?= =?us-ascii?Q?VFnlL7wNawP+qe/0e3V52x3Je0qBIEg/he5oBtAiC/zqIPTZjM17CUMJH3fy?= =?us-ascii?Q?96PqQaJJ92JusU0vpnOqgQeyMIEXgy3/e0LlogBcAbvP/AnKC/LYWAdkwFWk?= =?us-ascii?Q?d+77hg6urmfDz2zqUbqrY18tBz10jC8wWyUBO56pMTV93hiUHzjrGCbl6SZX?= =?us-ascii?Q?1KCng/bAD7trnW/Ism00OAZw4pFXpX1upjuPLYqX+S/go4UIZI7K94GWcKBI?= =?us-ascii?Q?+CwNWs7NSymlyp6XztczKAtJVhGF?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DS7PR12MB9473.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(366016)(7416014)(376014);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?L4d3/7JUvGi8E1faxTAusLSUaMd7C3NiErtdK8GJL56Y7efQ+9YMr7kWzHvx?= =?us-ascii?Q?pgfrpFwYOVBQ6SJwu439sCbX/blLQp4flneRYzgzC8KlKDZfsMFWBAA4lZsZ?= =?us-ascii?Q?c2PqLSk6VJTv6VD5bIXQBOdHvccfVJhA1WXrGmrqeBDP5ns6FUZubgLSNYlM?= =?us-ascii?Q?BGas8DzGpROhzG48BHp2ij0zr4yXkVC5rUw6YyyQU/2WMH2xQfJIkPm2SRfQ?= =?us-ascii?Q?fO/c23QuEIoA2FyHdNTcG36l2AAkml2OnfOA0CUeTi+ipPwvq6ggc1+maoYd?= =?us-ascii?Q?HrFDRIPbTaThWP6iwn1Sd26Bz18xdfRSl/OAdPjVwCfNayW56z7RzH89eDGN?= =?us-ascii?Q?anrO14U7cfQPDUayxKH5yNxa6ykTxd+heNktLxi1U5Gmj5ImUhITnBYdGJCh?= =?us-ascii?Q?zaHdCGs9nLYRj3VZezR66mO3pzBV8ztSxeFDdWjNGHd7jUYXteZGVn4IYBk+?= =?us-ascii?Q?uxFS2t9ZQipRxp/b+5TTtJV6C+eMzl1BTIWGaEQPVqJrQ78HrynIVFl88f6+?= =?us-ascii?Q?MSa8ZKzm/bRkLRFCUEctQ1hqUSVOxLBBSnkuC75kpDm3GlGLd+Tw/A89NtLB?= =?us-ascii?Q?FL9RxVsOxpfL/qg3b7MQiB02qdtf7DCFlHSwY/uGdPJerWO7//gkemadQ8GQ?= =?us-ascii?Q?zIPZxXoQ9ha/S24vrt6jTVbVFfgRNYGTnMky/V7pN99FVefScq6QegB4AhuH?= =?us-ascii?Q?WImo2aZ/Nc1+xcyJ/iQGPhNj69JSG9Oz6aIf0a0sITxcY+vbZEMk0zIw4EC2?= =?us-ascii?Q?ydoEUMCIk43kRLrcj8+Ggt6gVXrWvL8ZGkEKnFhfWuHNnYyttAridXSJ8qZ2?= =?us-ascii?Q?PncriiMaMi4ROOJcKZaRkDLorjEAbp40Nbjq4EuoO6T0V02jyRwt3lUZGLDu?= =?us-ascii?Q?44qFwF+BYvDy0EDF3Kbqk7voZes+bmmyaga17PiGomtuKPThwybgbXggjDWL?= =?us-ascii?Q?DVnZwBw/om199iwv4V/0cbcQYdGBUbnGjf4YmsY/gapvPKh8iHJWnxCs09u0?= =?us-ascii?Q?lMDRidr4II4bUN2u/3BPTUrNb+t83IhHwKkqyigziVVUFFxai8mDoiLXKUWh?= =?us-ascii?Q?BzEItpmOhJwSwU7htypwaWf7LaTUF13vtvw+2t1LselDgi5n5GYuubSwapRd?= =?us-ascii?Q?EEyePJREzFdYRVsnA5PRCEPJymkbOmjcyZ7FqznX865R2iGIyupyA+vfwyo8?= =?us-ascii?Q?3uP6OtI884ahd3CWje+rm/31KaYUqa3olOkavxlvu6Zi2hpv+dwE+zYErC2K?= =?us-ascii?Q?AcEpFA4lkWeqH8gQl0MtONhnSEhRXz/ETzuhdwtiUDQ+Wc56d0bA3ObG63MX?= =?us-ascii?Q?woa3nB6ntf1K/XrNQlGheVw81kNC7AibR67jmMuW7Z7Rok3rd9ZFFVKSm0Bh?= =?us-ascii?Q?nSzOa8tkXs2gawHw17RNvPLVvJ+NuzkOfXY3MZQMoh0mE0Ej1NsdoBb7JuQm?= =?us-ascii?Q?snpcb78h7B59GyTiTNVP69z0qvbhrPZE7rjffyIQRXh6W01xmbLHUlhnRJow?= =?us-ascii?Q?lgL5Xu5eXH7fMf2v48JH+1n/mCvUGtEXE7N/2KQaL+yK1DiAecNQmxl/KLbJ?= =?us-ascii?Q?azrNya460xKNQ5iLJEs=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: b8c08d10-85ca-49b4-fc0e-08dd5c29d4b4 X-MS-Exchange-CrossTenant-AuthSource: DS7PR12MB9473.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 05 Mar 2025 21:08:08.9797 (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: jhRtwYHhQuoynK+Frfu7QrXSG3g5gxcLpJ+/Jy0Ok42smtLm71DHE+c7WOfSmQ/8 X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR12MB6971 X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 7916E1A000B X-Stat-Signature: xqnn4eg1eqeegohzk694tby3gqxgm7um X-HE-Tag: 1741208893-617055 X-HE-Meta: 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 g25RSGwB WXbThteOUZ92mwur5FzQrWO24e3o4/c4Avjf+wTa1tzV2NuW6HacWvDGD2ilaPuB2E4pffkuIyYL678/SIoeIiTr0RW6YSd9Klc7rLfzLEBU46gPRL/51DJrhtA/Gwz7oi5YxrUrg79f3XcEkjC5kqBVgisQFVjysFWJRxcWMfirrIJQAiD/yzXauMCJIe/TZPtf87Bed2vXd+kd4s4DC9HNcxfA5T23QsqW2S/AL314bR2xAFsI9G9+28DIduWHUOipAg1NsnW5ADMk27xsLStzlEXkDB++x2bkF0VjQ4R3i2EFSA166j9G3HUvpx5Mh+/z8mynktMsffpLwwSXK/ep/Wmw4QOelv5h6gOP38nNY9ltYXL4pWjDHLw== 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 5 Mar 2025, at 15:50, Hugh Dickins wrote: > On Wed, 5 Mar 2025, Zi Yan wrote: >> On 4 Mar 2025, at 6:49, Hugh Dickins wrote: >>> >>> I think (might be wrong, I'm in a rush) my mods are all to this >>> "add two new (not yet used) functions for folio_split()" patch: >>> please merge them in if you agree. >>> >>> 1. From source inspection, it looks like a folio_set_order() was missed. >> >> Actually no. folio_set_order(folio, new_order) is called multiple times >> in the for loop above. It is duplicated but not missing. > > I was about to disagree with you, when at last I saw that, yes, > it is doing that on "folio" at the time of setting up "new_folio". > > That is confusing: in all other respects, that loop is reading folio > to set up new_folio. Do you have a reason for doing it there? No. I agree your fix is better. Just point out folio_set_order() should not trigger a bug. > > The transient "nested folio" situation is anomalous either way. > I'd certainly prefer it to be done at the point where you > ClearPageCompound when !new_order; but if you think there's an issue > with racing isolate_migratepages_block() or something like that, which > your current placement handles better, then please add a line of comment > both where you do it and where I expected to find it - thanks. Sure. I will use your patch unless I find some racing issue. > > (Historically, there was quite a lot of difficulty in getting the order > of events in __split_huge_page_tail() to be safe: I wonder whether we > shall see a crop of new weird bugs from these changes. I note that your > loops advance forwards, whereas the old ones went backwards: but I don't > have anything to say you're wrong. I think it's mainly a matter of how > the first tail or two gets handled: which might be why you want to > folio_set_order(folio, new_order) at the earliest opportunity.) I am worried about that too. In addition, in __split_huge_page_tail(), page refcount is restored right after new tail folio split is done, whereas I needed to delay them until all new after-split folios are done, since non-uniform split is iterative and only the after-split folios NOT containing the split_at page will be released. These folios are locked and frozen after __split_folio_to_order() like the original folio. Maybe because there are more such locked frozen folios than before? >> >>> >>> 2. Why is swapcache only checked when folio_test_anon? I can see that >>> you've just copied that over from the old __split_huge_page(), but >>> it seems wrong to me here and there - I guess a relic from before >>> shmem could swap out a huge page. >> >> Yes, it is a relic, but it is still right before I change another relic >> in __folio_split() or split_huge_page_to_list_to_order() from mainline, >> if (!mapping) { ret = -EBUSY; goto out; }. It excludes the shmem in swap >> cache case. I probably will leave it as is in my next folio_split() version >> to avoid adding more potential bugs, but will come back later in another >> patch. > > I agree. The "Truncated ?" check. Good. But I do prefer that you use > that part of my patch, referring to mapping and swap_cache instead of anon, > rather than rely on that accident of what's done at the higher level. Definitely. Best Regards, Yan, Zi