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 958B2C61CE7 for ; Wed, 11 Jun 2025 12:34:31 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 03B7D6B0088; Wed, 11 Jun 2025 08:34:31 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id F2E1F6B0092; Wed, 11 Jun 2025 08:34:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E1D936B0093; Wed, 11 Jun 2025 08:34:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id C360B6B0088 for ; Wed, 11 Jun 2025 08:34:30 -0400 (EDT) Received: from smtpin27.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 7A0B71A0BDF for ; Wed, 11 Jun 2025 12:34:30 +0000 (UTC) X-FDA: 83543063100.27.279AA61 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf16.hostedemail.com (Postfix) with ESMTP id F3E46180012 for ; Wed, 11 Jun 2025 12:34:27 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b="ImD33hA/"; spf=pass (imf16.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1749645268; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=CeP4mQyu/RwYyyIh9i2z9hAz1X4g/i9DF9d0mMlEaXM=; b=PHyJH0njDM/z53dy7DEjUjBX2DJPdNDp7UsHMrCFY0MmFQeztAveCiuawnPf6ou05gUR8I Ihz3VtKjUF4DTaXEdToDwrqavww9oN4QgWf5EdHysWNb08bywpKdcY2PD1fshUwC52pDpl jcvaWxHe0sBf1GtbMRZ+j90P2arvVaY= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b="ImD33hA/"; spf=pass (imf16.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1749645268; a=rsa-sha256; cv=none; b=K0IlwILJkyV5KIw+xc6nalBH6I/FOfPZef/dFw0oZVaibyDcbykAaagpj5xbB9K1NNv9xg /rGh1aCGu8mLlbt/dZYHiXU2o3mAs6+qwPqc+oDsLuyiCa3XM/HCMm8KrETjEOMlAWyOXS 9Y1hECPo1wktbhQFqxAd3mdrNz5QYZo= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1749645267; h=from:from: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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=CeP4mQyu/RwYyyIh9i2z9hAz1X4g/i9DF9d0mMlEaXM=; b=ImD33hA/VFbZxbTW/gLYUfyACNyEbTivn1QZXc/MKtPO6/u0d26VZiZylstenQEDYfMcve 64m90zYVFF1jPdYd9TO+0GjZrmcX4KKAieaNEzX7lQPI9CHBcNdcp7wuyqmWqgNLFVgTyD wgQBdNq8iwHfZtetZDv7QD6+14ca3cU= Received: from mail-qk1-f198.google.com (mail-qk1-f198.google.com [209.85.222.198]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-500-smi4ohT1Nfe-lgRIO3eQmQ-1; Wed, 11 Jun 2025 08:34:26 -0400 X-MC-Unique: smi4ohT1Nfe-lgRIO3eQmQ-1 X-Mimecast-MFC-AGG-ID: smi4ohT1Nfe-lgRIO3eQmQ_1749645266 Received: by mail-qk1-f198.google.com with SMTP id af79cd13be357-7c793d573b2so1106582485a.1 for ; Wed, 11 Jun 2025 05:34:26 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1749645266; x=1750250066; h=content-transfer-encoding:in-reply-to:organization:autocrypt :content-language:from:references:cc:to:subject:user-agent :mime-version:date:message-id:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=CeP4mQyu/RwYyyIh9i2z9hAz1X4g/i9DF9d0mMlEaXM=; b=haPapsHjGGIXjPyflhb5zkQho6wulVHkXC2P6OIeSm2KxXiyfeDsdF5s7ir9ZYksVr gnxgC2vYd8erp2U5jb47BwXudstT777EGH1wxBZWrj4gUYP2qhE76UqR2ILwBnq7McU/ mcRFA/hbSmmZAPMqqwsVA9RjbLwbp5Or7wrEDOUTChjZlUmASGk2jpIsSliUrwXEtlt5 bd9meC9pJoDBWhJWupAUjSzkqyrEIM2sI0GYNi+TKlPZ/1vnVgN3R+uc54+CtYCVJI5S 8BPN8ND/q8Xa82RC4TAarFsrsEow7IIMI7vhGfe3F14ez4hwnBaR1P4fi8UlVflkE8/L 65gA== X-Forwarded-Encrypted: i=1; AJvYcCXas8k4M5lpXfFmO0uOzueWN+2dMWQJPPO+sQbOcbuPQarFeaaVaGhqPfcUHBzjXaeBRZgooOMRyA==@kvack.org X-Gm-Message-State: AOJu0Yy1+MwncrVEui/ecHivXlbdMuw81QyOC8kGrNBpy3INpFsKzwkI +MwYSEBqiDirRNB8tzb5sN5TBFMoz6yYyS6MY0TXfEWUw70rWXl0Ditoe0I9oKBlpIR1mXEn/DR wGR2Cg1SSW4q/OTfpBcB2SBwDFCagOySt8DhGpQ0a0IRZ2+skfvXx X-Gm-Gg: ASbGncv8AskI7Y61UgkX+t/DXKvvQVdxj2iB8X0w6A6e6U8c6oEeLE6nzAEsUJXJtsB ZG4pr9Zm2Vi+VUwgRElq1mVUP8CVtBultdO/iHX2y6RXkd/jIP+MBfYRQyNs1D+FQceJY7gRq1A lhT1kMV0sf9zh08rgREIQLmKfV5SQE1Fng3pLebvt/D0Kziz8gjX+yM/7gYM6FmMu7Xuh6VyF8H VE1DO3YF9rBPkmZQjizZ+3tWqS31JUyD7Mk3CFwBDLp+ZpO9vINt9m9m6g60gZxzzZRiQqAssyl RI9rmpT577NdGSYFIBqBz3A7+LAMBbha/OGm3d1qo51Y X-Received: by 2002:a05:620a:294a:b0:7d3:8472:7f9f with SMTP id af79cd13be357-7d3a89d9c17mr484257885a.50.1749645265747; Wed, 11 Jun 2025 05:34:25 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFAwzDboK/QnSv2d0esNXrw0qSuQbL8/45IXsgrBCmd4uKV+4TDuSnq++1f1FeKwz6ZXMg8Wg== X-Received: by 2002:a05:620a:294a:b0:7d3:8472:7f9f with SMTP id af79cd13be357-7d3a89d9c17mr484253585a.50.1749645265351; Wed, 11 Jun 2025 05:34:25 -0700 (PDT) Received: from [10.32.64.156] (nat-pool-muc-t.redhat.com. [149.14.88.26]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7d25a608c45sm856080485a.59.2025.06.11.05.34.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 11 Jun 2025 05:34:24 -0700 (PDT) Message-ID: <1ec368c4-c4d8-41ea-b8a3-7d1fdb3ec358@redhat.com> Date: Wed, 11 Jun 2025 14:34:22 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/2] mm: huge_memory: disallow hugepages if the system-wide THP sysfs settings are disabled To: Baolin Wang , akpm@linux-foundation.org, hughd@google.com Cc: lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, ziy@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <8eefb0809c598fadaa4a022634fba5689a4f3257.1749109709.git.baolin.wang@linux.alibaba.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <8eefb0809c598fadaa4a022634fba5689a4f3257.1749109709.git.baolin.wang@linux.alibaba.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: sI9-PgYQxuIWwY58LdTfEF5dsVjUYCgSLi9LrG3aNoc_1749645266 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: F3E46180012 X-Rspamd-Server: rspam07 X-Stat-Signature: pf5xsu9rqrjhtn9qzrwtyse17wmnq68j X-Rspam-User: X-HE-Tag: 1749645267-750979 X-HE-Meta: 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 mAxP5OOh 5nstg09p2Hn1kb3SXUcA/bDTRmWAs9NVVv419qbwBjnCAZuxVUv+7Qi7MzZgKqLIFMgRq6GoEQbCBg+4wA0Omj1Htknvr4ZPzO+HQYSV1dnAj5WZ2bRPfhao8UzwPmgqyUFNwXat/tLcsRbT8zOXyFUDtd5rNij5+0nxDNxOuOl3PxM0VEWWBidatZtYLJMrfK8wFN4+RHB2u25ETUtTsoCCwOpQXs6hRigMvFrdbq2dibm7SqevvfOmGI7CGtvJ1yZ/0MXVX5nRMjeU6FbiTLiEBVx5MTq2SWo3aw+8ZHHf88pQWGR3UuaYZaZ4ufAdT+xBfc3hdH5/yaceAbb/XQDRoqM4OESXOFlP0OaJH7HFxcQ+c/70/GFlofuUtGwzEnvu2kHaYRzVYW62SDy2hLfetGrEdRAEKmXoUXqNiIeFVKEj6Dvn1pYrufsVUJJ5a2SgFkRavkr3e0moEdYIVReldT2oUQcXcY0HmXW7wpqWw6wAD8uruanI/pLMgCRMlmh5xLvVQffZ+UIH8u4bsuA0ZiKuteAEFfPub 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 05.06.25 10:00, Baolin Wang wrote: > The MADV_COLLAPSE will ignore the system-wide Anon THP sysfs settings, which > means that even though we have disabled the Anon THP configuration, MADV_COLLAPSE > will still attempt to collapse into a Anon THP. This violates the rule we have > agreed upon: never means never. > > Another rule for madvise, referring to David's suggestion: “allowing for collapsing > in a VM without VM_HUGEPAGE in the "madvise" mode would be fine". > > To address this issue, should check whether the Anon THP configuration is disabled > in thp_vma_allowable_orders(), even when the TVA_ENFORCE_SYSFS flag is set. > > In summary, the current strategy is: > > 1. If always & orders == 0, and madvise & orders == 0, and hugepage_global_enabled() == false > (global THP settings are not enabled), it means mTHP of that orders are prohibited > from being used, then madvise_collapse() is forbidden for that orders. > > 2. If always & orders == 0, and madvise & orders == 0, and hugepage_global_enabled() == true > (global THP settings are enabled), and inherit & orders == 0, it means mTHP of that > orders are still prohibited from being used, thus madvise_collapse() is not allowed > for that orders. > > Reviewed-by: Zi Yan > Signed-off-by: Baolin Wang > --- > include/linux/huge_mm.h | 23 +++++++++++++++++++---- > 1 file changed, 19 insertions(+), 4 deletions(-) > > diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h > index 2f190c90192d..199ddc9f04a1 100644 > --- a/include/linux/huge_mm.h > +++ b/include/linux/huge_mm.h > @@ -287,20 +287,35 @@ unsigned long thp_vma_allowable_orders(struct vm_area_struct *vma, > unsigned long orders) > { > /* Optimization to check if required orders are enabled early. */ > - if ((tva_flags & TVA_ENFORCE_SYSFS) && vma_is_anonymous(vma)) { > - unsigned long mask = READ_ONCE(huge_anon_orders_always); > + if (vma_is_anonymous(vma)) { > + unsigned long always = READ_ONCE(huge_anon_orders_always); > + unsigned long madvise = READ_ONCE(huge_anon_orders_madvise); > + unsigned long inherit = READ_ONCE(huge_anon_orders_inherit); > + unsigned long mask = always | madvise; > + > + /* > + * If the system-wide THP/mTHP sysfs settings are disabled, > + * then we should never allow hugepages. > + */> + if (!(mask & orders) && !(hugepage_global_enabled() && (inherit & orders))) > + return 0; I'm still trying to digest that. Isn't there a way for us to work with the orders, essentially masking off all orders that are forbidden globally. Similar to below, if !orders, then return 0? /* Orders disabled directly. */ orders &= ~TODO; /* Orders disabled by inheriting from the global toggle. */ if (!hugepage_global_enabled()) orders &= ~READ_ONCE(huge_anon_orders_inherit); TODO is probably a -1ULL and then clearing always/madvise/inherit. Could add a simple helper for that huge_anon_orders_never -- Cheers, David / dhildenb