From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from CO1PR03CU002.outbound.protection.outlook.com (mail-westus2azon11010060.outbound.protection.outlook.com [52.101.46.60]) (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 2E1B23FD128; Wed, 13 May 2026 12:06:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.46.60 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778673993; cv=fail; b=jF3V6I7nu40Wz6TZesq4qUs1sgNBbrjdJEwrPEXy1mqaV81DIB4zqECcWAyUoLDDNvflbTfHg4XRVsUpMEz1Zq/j9kGsZo/WrrDOn8OLYKmHjJtaRqFgEZ2reesjIMwsAbtfyGpeAFfUxisqxLX6qUTsIM8GZ5n0LgOESPWvcRI= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778673993; c=relaxed/simple; bh=aZwW7ae5qdlVXLy+HqvdpEMiXPZYKiw0QT7p8yE9vvY=; h=Message-ID:Date:Subject:To:Cc:References:From:In-Reply-To: Content-Type:MIME-Version; b=IqLxr6Rs4gfZJvAo870p92TgvPS3v9eifSuGfguEU6ZWrL2czeieQhrijyA/VxgnYGCkuOhUlZF4olyPyqAozuMwpYKiD/vgxqXlfHFuWvR9wv/gzmLCdE9FmDNf52liGATqbVaggPyfvDtivrbhHOhTmj9Z3rcodehWr+ULKyE= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com; spf=fail smtp.mailfrom=nvidia.com; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b=M/HsxqJY; arc=fail smtp.client-ip=52.101.46.60 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=nvidia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b="M/HsxqJY" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=ymjESS/uJse1v7fZGUFF6kWDzTwpR1bP0S74A50IQchsJK6WenrVvs+8S5t4H+UrceWDxCvY6HwQ3ww/yRwpkUUQvKY3R/xwM9AHs60k9c06pXiMukDOimLVvGjwDhKfW7EOrXXwISxDlWTXdeChhuxb+8wOk31T3LSgKsx9nKQ22k603zUmiOfkcEkgg1faB8eYDYdQPDgHHsK6kCTZkzxAumceCTsMaecykJHJW6yzl06agWrmXQ8EryaCxkJ25pLaj2MknNuNpct4us9mihUZVM6GEOJqUWS3ET+F3XPWjNVcHIt78MZfJyDoId6nlihFQMRoRQha+lcNKpV17A== 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=0o+loa06WTgPZxij1Ofn7VOfJnxWmqooT6LwKwNV+0I=; b=sz6tqn1Y9zg9oMhHrnhCULbd1hpHOplA0UEK6mcsuHD2zKavRBewHFILNONKW5f+x21bJcWRufSmHyp8k6G2sVW6Jyh8av/8siOvsoFRiyxtNWr/J7wlkBJWuzl5iPVlAx6MTw/CZNMDbs+pbvJNlOeyj7xFDU0siMkpqDTfGfuUrD4ytbNLQ/4krA5zlJBR+JoNxGDVykK52Uab0TSC4GdCyjDXXH5CjovTVKvoR6AK9JJU/jhZX+IxcmFRRpISyyztzQdfpqxAtw6ZdfEE9pd/VemlbK+mt/LU2XkoibcbDYs4I18D7xlW+k1kJkj0KWBEBIl53tISwTW97+foww== 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=0o+loa06WTgPZxij1Ofn7VOfJnxWmqooT6LwKwNV+0I=; b=M/HsxqJYepRfqwkkrBrcdhKbFSh6NfVRj1Yi83/PucirDPugQ+/XjtNU9fnNWtEectWQL046V/U7tDa0o4Rg4Jv2XaYU5k2Xq+86wlUlNEQ4/950zSZ1MQEnfqZai3so4v0d5st1/jmltWwyC2JpFxX/VTcU8iH4kVJym3taga65ZNRlOnnJTNbTbYDLP4iyUo6ieFpOJelU16VuzVSj77+BJy5CqLf+XfJGp/yEN2O0LWzdA2Ee4xrTr9B37ZD1Pmt/5NIMRiclQV8caXgiEfRNfBKJzgckRHX0Li2KSct3E9M2f7DOSUUhki5CWCQyfo/Xq++D8+wVYKQ6+CdWIg== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from CH3PR12MB8728.namprd12.prod.outlook.com (2603:10b6:610:171::12) by DM4PR12MB7671.namprd12.prod.outlook.com (2603:10b6:8:104::17) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9913.11; Wed, 13 May 2026 12:06:16 +0000 Received: from CH3PR12MB8728.namprd12.prod.outlook.com ([fe80::2641:1046:bdf3:93d7]) by CH3PR12MB8728.namprd12.prod.outlook.com ([fe80::2641:1046:bdf3:93d7%7]) with mapi id 15.20.9913.009; Wed, 13 May 2026 12:06:16 +0000 Message-ID: Date: Wed, 13 May 2026 14:06:06 +0200 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4] mm: introduce a new page type for page pool in page type To: "David Hildenbrand (Arm)" , Pedro Falcato , "Vlastimil Babka (SUSE)" Cc: Byungchul Park , linux-mm@kvack.org, akpm@linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel_team@skhynix.com, harry.yoo@oracle.com, ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net, kuba@kernel.org, hawk@kernel.org, john.fastabend@gmail.com, sdf@fomichev.me, saeedm@nvidia.com, leon@kernel.org, tariqt@nvidia.com, mbloch@nvidia.com, andrew+netdev@lunn.ch, edumazet@google.com, pabeni@redhat.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, horms@kernel.org, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, ilias.apalodimas@linaro.org, willy@infradead.org, brauner@kernel.org, kas@kernel.org, yuzhao@google.com, usamaarif642@gmail.com, baolin.wang@linux.alibaba.com, almasrymina@google.com, toke@redhat.com, asml.silence@gmail.com, bpf@vger.kernel.org, linux-rdma@vger.kernel.org, sfr@canb.auug.org.au, dw@davidwei.uk, ap420073@gmail.com References: <20260224051347.19621-1-byungchul@sk.com> <982b9bc1-0a0a-4fc5-8e3a-3672db2b29a1@nvidia.com> <4af19eda-c29c-4302-92d5-c0915267fc0c@kernel.org> <1817a749-8232-43ab-a0f5-350e5aade235@kernel.org> Content-Language: en-US From: Dragos Tatulea In-Reply-To: <1817a749-8232-43ab-a0f5-350e5aade235@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: FR4P281CA0053.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:cc::18) To CH3PR12MB8728.namprd12.prod.outlook.com (2603:10b6:610:171::12) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH3PR12MB8728:EE_|DM4PR12MB7671:EE_ X-MS-Office365-Filtering-Correlation-Id: 8ffb8f3f-13e4-424c-c0b0-08deb0e8089d X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|1800799024|7416014|376014|11063799003|22082099003|18002099003|56012099003; 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:CH3PR12MB8728.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(366016)(1800799024)(7416014)(376014)(11063799003)(22082099003)(18002099003)(56012099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?UnlTT3kvMXRTMXVWeFhTR214VkkvWkV2b1hhL2ZHWWE5bW50dGJIdzBxaUZ0?= =?utf-8?B?WTZRV1dzSUs1cEt3WkEzc2VMdmtBNG16NTcvTWduNzFsSUlvcFBsRjVXYW9j?= =?utf-8?B?TS9FaTFJNlJocG1YbTZXSHRzaEFzdjJEbDZYNTV0OGdPWGY5MlhNRUpvdUl3?= =?utf-8?B?a0Vwc09xcHU2OE4ya0NWTkliWHpTVkErT20zbVlaeHpQK3hISnNzeHhrMTY3?= =?utf-8?B?a3JuTVUyd3JvSEhaVzFJd0lrL2dCd0w3QVdiRDViSldXVVFmZU1qK1hqNUw3?= =?utf-8?B?TFQwbGRNV3U1RlFEd0pKUlRDTEpnRW5EeUoycjBzZVVOajFwRVYzL0s4bUtR?= =?utf-8?B?bit1T2ZTNmZKU0NQTzBnZlhETVFNa1FCZmpJS1FCMXBHemxYUDcrd01PeUlR?= =?utf-8?B?QjZtNzNIRGF1V2hLWGV1aWJqSUVRZFROMERlVHltMjE3K0twSit5Wk4vR25z?= =?utf-8?B?WUNKUTFSTEZnckZoVzliZmtES2p1QXA5NTQvRmp1RkFWNEJUdWlVYWp6Ry9W?= =?utf-8?B?eHhvUDBiRXBpRHlBMjNCUnJoRHNmYitOdWJJcWFNWXlQVXhiSWppZklRV21m?= =?utf-8?B?MHYvc2ZxMWZvWGxVQXRheVk0YkpOYVRIZmtzL1VWMVZ1QTlmVFpFS1dQVDNS?= =?utf-8?B?RXNQZklLZWZxVzdvb1BFQitkY0xCbG55cUxudXJ4WWRLVm1PeEh5Nm5yN0hV?= =?utf-8?B?a3gyTjgvR09GV3NTT0FUTlFVL21ESGM2NFArSlFpUFpBbTkvYkVHWElSZ3Av?= =?utf-8?B?NldwOXpqYWNFYTlueURTNTlFYVMzTllzUVJBcDBnUlRQYi9rRlVWSWtTL3R1?= =?utf-8?B?d0tYVGRmV0tqK2tFeWpSdTBlblRCZ3pSaGVOSkN6US83bWl1VU1mQ3pwbFMw?= =?utf-8?B?Zy9xWHFSbk4waTlDVFFUVmg4ZUY2TzlJQ2JSVXlhWGVOcWVMSTdXa1R1NlMy?= =?utf-8?B?c1lBN0YwT3NCam5QODJPUG5UTHgzUzRKdDJHQk45VDRVMEozbVdaVlJtWlFQ?= =?utf-8?B?VDdNZGE5Q2wraC9vVmIxanpkeCtiamRhRGs0OGVoMlgvSGpOdUFiUmVtSWh2?= =?utf-8?B?d3Rvc2dFNlhZZStJSUxFMXA2U0xuWkxVazIrUW5UdUlhTzdEc3lUMnNZRE9U?= =?utf-8?B?THlhRitpczZJQ1hIc0VMMUhZQzk2eEdDUWVBYjZiZmlkbkZHT2dsQ0FjZk5j?= =?utf-8?B?eDAvbzR3dkNrMTdFSC8zcG5qbW9sNU1FYmpielBpRXRzUlhqaUtmeFYzR2I4?= =?utf-8?B?NnFmTTM3TjJWN1FOYW5YU2VmZ2pKcWRKZXFHV0FrWXlONkNTM0VXSjRILzZN?= =?utf-8?B?dDVzUzdHVmFpZmluaVlyQkNhZ2Q5UmFybVd1ai9BUDFkc1VDM0FncjlYVFBW?= =?utf-8?B?aTRwSllwbUJwS2s5VnEzdENEY2FqSU1KYmkraC9kVkFVN1JaVG4xZE1ieUJP?= =?utf-8?B?YkJnQ0hLUDhRV1cxak5NQVh0ZE5kQ0ZXT3hCVzdWUWxSMmNsS2taejZHR2or?= =?utf-8?B?c0puRnlrb09uaVhDVTl6OGdGOUI4cHk5ZjFsV2pqaDllRWlGZ0o5WS90RStG?= =?utf-8?B?VVF3RjRHOHI5aUhoRjFYcVlSc29qT2VtTWpaRFZqK0xaNzlrMG9nU1FYdWsv?= =?utf-8?B?YW9CWG9iQTdxa1Aya2paSFFnQ0grejVPYVdCRlRtbjNCK0E3d3lJUU9xd0Er?= =?utf-8?B?TVRlNm9HRXhYVzRBMFpqT0FvTFIvdXJaWDlJREh1N2NLdUdQV3k4TXU1VUU2?= =?utf-8?B?b3grSXdOV2RtdWNXdExhT3NaMW1yK1R0MjlDYU13RXBBa2FIVUlTbTRLa3FL?= =?utf-8?B?WTcyaXp6dHlRckJvRk5kYTNCM2JpVVhoMGpuYTRERzFnRHRibmtMUVNyYStw?= =?utf-8?B?WTA0Rkl2YlpPMGVRZndPcVpwZ09ObmExUjN6N2VtOFd3MFJDMm9tbVcwZmhQ?= =?utf-8?B?ZnZOajVKSHpHWWNPekQwV29ZTit3MCtTWFo3K3hZTUszRmVXM2pMdFdKTzdN?= =?utf-8?B?N3B0NnRJcEZXaDFhNCs1OFFoTVFlUkVybWNvODk5T1MvSUt5aTZxS1I5VkVL?= =?utf-8?B?VUNGUzUxYWZCdnJtcmsxcGVqMW9nKzEyMjk0d3hCcDZSaWRNd21HeTRVWmxp?= =?utf-8?B?amNjS1E1VjV6c3Q4UC9sYnUxa29TUThqdFF4aEVNOEdBdlNraU95WlFEeGly?= =?utf-8?B?QVh0NFFFRDBUOVVXR3o3VERwQ1htYU4xUm1pRDRhSUp1QnZvTHA0eVJNZmcw?= =?utf-8?B?Nk5ZZkVzb2swWVJOaUkxZS9zSE43VisrRzBnekZlZ3F2NEYxN3c3S3VteDln?= =?utf-8?B?UFdQWm9NeXVTRGNMd2RvQ1FEbEVYMDNMNjUxL24wRWZZTmxiejBIdz09?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 8ffb8f3f-13e4-424c-c0b0-08deb0e8089d X-MS-Exchange-CrossTenant-AuthSource: CH3PR12MB8728.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 13 May 2026 12:06:16.0121 (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: 3HpqWrBp7H5acuLUCJMTZZvfWsRotzxhWlNItFBZgaPzuf6kvWzyagWlxSvwxYjgK60WOX1AndayWwBttBe9kg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB7671 On 13.05.26 11:36, David Hildenbrand (Arm) wrote: > On 5/13/26 11:26, Pedro Falcato wrote: >> On Wed, May 13, 2026 at 11:12:43AM +0200, Vlastimil Babka (SUSE) wrote: >>> On 5/13/26 11:00, Dragos Tatulea wrote: >>>> >>>> >>>> >>>> Seems like this patch broke tcp_mmap because >>>> validate_page_before_insert() returns -EINVAL due >>>> to a page having a type. Here's the full flow: >>>> >>>> getsockopt(TCP_ZEROCOPY_RECEIVE) returns -EINVAL because of the >>>> below flow in the kernel: >>>> >>>> tcp_zerocopy_receive() >>>> -> tcp_zerocopy_vm_insert_batch() >>>> -> vm_insert_pages() >>>> -> insert_pages() >>>> -> insert_page_in_batch_locked() >>>> -> validate_page_before_insert() returns -EINVAL >>>> because page_has_type(page) is now true. >>>> >>>> The patch below fixes the issue. But is this a valid fix? >>> >>> Hmm the check traces back to commit 0ee930e6cafa0 "mm/memory.c: prevent >>> mapping typed pages to userspace" >>> >>>> Pages which use page_type must never be mapped to userspace as it would >>>> destroy their page type. Add an explicit check for this instead of >>>> assuming that kernel drivers always get this right. >>> >>> So uh, this doesn't look good I think. >> >> Yep, you fundamentally can't map a page with a type as page type aliases with >> mapcount. Even with the given diff, just mapping it will increment the mapcount >> and wreak havoc. I think we need to revert this patch for now. >> >> I'm not sure what the long term plan for this would be. If page types are moved >> to memdesc types, then the two stop colliding and that could work. I don't know >> if that's Willy's plan, however. >> >> (then there's the other question: are page pool pages really folios? not really. >> they are mappable, but they aren't part of the page cache, or anon, nor are >> they in the LRU or have rmap capabilities. perhaps we need a different memdesc >> for those. we're one step away from reinventing class polymorphism from first >> principles ;) > > Zi Yan is working on this: non-folio pages would no longer mess with > rmap/mapcounts, and page table walking code will identify them to be non-folio > things to skip them. > > It will take a while, though ... > So do I get it right that the path forward here is to revert this commit [1] and wait until the work from Zi Yan is ready? [1] db359fccf212 ("mm: introduce a new page type for page pool in page type") Thanks, Dragos