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 3CBF9C02193 for ; Thu, 30 Jan 2025 09:12:34 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A68CF28027C; Thu, 30 Jan 2025 04:12:33 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id A173228027A; Thu, 30 Jan 2025 04:12:33 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 86A8828027C; Thu, 30 Jan 2025 04:12:33 -0500 (EST) 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 63EB528027A for ; Thu, 30 Jan 2025 04:12:33 -0500 (EST) Received: from smtpin09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 1A7A2B0C03 for ; Thu, 30 Jan 2025 09:12:33 +0000 (UTC) X-FDA: 83063552586.09.9C0F16C Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf26.hostedemail.com (Postfix) with ESMTP id 8C4D514000D for ; Thu, 30 Jan 2025 09:12:30 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=FpzVNkSQ; spf=pass (imf26.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1738228350; 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=rLOz0obAD+oiqNRoo0TPuKVd7dXq0sfd2ABPZioYnD4=; b=tJtx9dM7mJPPpMr1lUyoyQSfTyFj15f76ZItViUS60abUF+LEqx5esMD4OcztjEgT+Zrhg alesD5z/mr8qW4xz4iG3Iat1rB7QgCS8mtavAKrci7zLGdJ3dwrTW99G/w+3nEGe09fM3h nv4nhE+l3AATu7yoY1W0Wr5mLCS784s= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1738228350; a=rsa-sha256; cv=none; b=5JovMvs8nqyimSoVw6QiuoaJoMSvLFp3FHEKqKE/QTDb8OvPOUCNBNAa8iYRODPHAEGw40 eVBtBJBhjHg7UoHxeUul8GGsnsOkyxvW6WsJRLlXkKZJNwqCGp+a16oB8km6j4dM53Vtwo zwdTdiM/BELEy5UnXotrEGR0+S5f78E= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=FpzVNkSQ; spf=pass (imf26.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1738228350; 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=rLOz0obAD+oiqNRoo0TPuKVd7dXq0sfd2ABPZioYnD4=; b=FpzVNkSQAcOMEU2StUIEIaQMEReN2PJhBzXEmub5AiHXUpkdbwoa9woMlKcP+oQfkfQYSI 7+JAgpFg1jCt6Dl2QBmrSAP/QiWkOcS35OpdS3tlmJcpKXlIVG47XzZg0BZ1PXvxRcohuN S7QVH4KfpFhnHKUJBFc6AHYkR3on5Lg= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-553-qe5qQDCVMgGLuK8MScDdcg-1; Thu, 30 Jan 2025 04:12:28 -0500 X-MC-Unique: qe5qQDCVMgGLuK8MScDdcg-1 X-Mimecast-MFC-AGG-ID: qe5qQDCVMgGLuK8MScDdcg Received: by mail-wm1-f72.google.com with SMTP id 5b1f17b1804b1-4361ac8b25fso2429975e9.2 for ; Thu, 30 Jan 2025 01:12:28 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1738228347; x=1738833147; h=content-transfer-encoding:in-reply-to:organization:autocrypt :content-language:references:cc:to:from:subject:user-agent :mime-version:date:message-id:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=rLOz0obAD+oiqNRoo0TPuKVd7dXq0sfd2ABPZioYnD4=; b=rQHK59+nYkxY4YMdWBBxghmKHQtzPRHVlajq5RtJqKiXWh5sn6zYe3u0Hf1pPAj+LU j9LD4RxAakk/3VEP3CYqiw9JWFnKUQ+t7tTShHiYryQ6CFCQCU+6vVDbQbpMOqvdJDxb ko7TNDVOFUYlX0DOSdRdHLEc/X8teLvja9PEnNJZnV1ilHjH8j1gI/Gbp+gLRe+ECh6p GOhn5G78l2QCtDqlA1hvH7b0UJAUW+vrWvajqdmoGA/qDKoyX9RGOSMgploapyr2A6I4 ybZ6gOaH4jlbNdegQndquPbKIrGEg8hGhhpgrBfEfWrl11HKMZdgXSwGBH7tZktoHM04 L2fg== X-Forwarded-Encrypted: i=1; AJvYcCWuGxpzW2TfNqLn5eDOKzj9AeNvm20iKcIS010YtYBbVlB0602g91zzS953ukH+zT/0BIvaxNSKcw==@kvack.org X-Gm-Message-State: AOJu0Yw1WrQIdYHj0ZGU5OVQRBTKm4eBMjWgr496K8v7oOpc3V+2ggry 5wIz/jn+puzC6+hH4Ep7YUGaQ8LWCeNZILFHf8xf8QjoA+zDLEJLHF3Bro+DdRQRLfvEbgCxf84 it7JGLLxOgnDu24NBVqicerNIsPauzmPdqWblqJIhDrbJYAxI X-Gm-Gg: ASbGncuScD6+y1ZATifP87IUUwWnRHctOhFOXddVqg/WoPj/Cqv3SfU0pnKMgW8Pz0/ NDqYiO9f8k53YgvT7Sw9mlMpfj50ww5J+w29i0UvkkdehwMrlHOEVPQncF06eIpRT/d3oBATi79 mUCze3BwtfIwngqmZZeZ0ryVK0Z6tkYI0wfD96fmyE9SCpQgEncyQusYDIQvGvffYOUrbrdMzvY AEefJ/aCCX9bV+75aXPPmCH/MPvVGvSgIVvXnHVBCS+wgou3tcHqgdF9K6RaAHQpiN3WMG939pM 5GU/Jagjf6511X+f/dvEx679KJztHJL/Qi5vv9OFUWZv X-Received: by 2002:a05:600c:3585:b0:435:192:63ca with SMTP id 5b1f17b1804b1-438dc3fc57cmr47679785e9.21.1738228347397; Thu, 30 Jan 2025 01:12:27 -0800 (PST) X-Google-Smtp-Source: AGHT+IGwVJCk7i8Wi+y4cB3+BrJijTjRz9/U6vW5B3DRIl8pEv+r5QnVS78KcctKOfglkPsCjp7UdA== X-Received: by 2002:a05:600c:3585:b0:435:192:63ca with SMTP id 5b1f17b1804b1-438dc3fc57cmr47679455e9.21.1738228346964; Thu, 30 Jan 2025 01:12:26 -0800 (PST) Received: from ?IPV6:2a01:599:904:96e0:a245:aa9f:6c57:eb41? ([2a01:599:904:96e0:a245:aa9f:6c57:eb41]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38c5c0ec35asm1397002f8f.15.2025.01.30.01.12.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 30 Jan 2025 01:12:26 -0800 (PST) Message-ID: <547f6335-ceb4-4160-ba72-5214bf5c82f3@redhat.com> Date: Thu, 30 Jan 2025 10:12:24 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 04/12] mm/rmap: implement make_device_exclusive() using folio_walk instead of rmap walk From: David Hildenbrand To: Alistair Popple Cc: linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-mm@kvack.org, nouveau@lists.freedesktop.org, Andrew Morton , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Jonathan Corbet , Alex Shi , Yanteng Si , Karol Herbst , Lyude Paul , Danilo Krummrich , David Airlie , Simona Vetter , "Liam R. Howlett" , Lorenzo Stoakes , Vlastimil Babka , Jann Horn , Pasha Tatashin , Peter Xu , Jason Gunthorpe References: <20250129115411.2077152-1-david@redhat.com> <20250129115411.2077152-5-david@redhat.com> <7tzcpx23vufmp5cxutnzhjgdj7kwqrw5drwochpv5ern7zknhj@h2s6y2qjbr3f> <180e9c2f-51fe-44ba-ac68-5aa7b7918ab0@redhat.com> 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: <180e9c2f-51fe-44ba-ac68-5aa7b7918ab0@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: _ozBgfILKXIcTeaRiGzoAomWYHJpJnFw4d4pkV-gguU_1738228347 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 8C4D514000D X-Stat-Signature: wzdxpbmeq56frdgdnzh6ofq4bhipnxs3 X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1738228350-629869 X-HE-Meta: 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 VRYIBt5/ 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 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 30.01.25 10:01, David Hildenbrand wrote: > On 30.01.25 07:11, Alistair Popple wrote: >> On Wed, Jan 29, 2025 at 12:54:02PM +0100, David Hildenbrand wrote: >>> We require a writable PTE and only support anonymous folio: we can only >>> have exactly one PTE pointing at that page, which we can just lookup >>> using a folio walk, avoiding the rmap walk and the anon VMA lock. >>> >>> So let's stop doing an rmap walk and perform a folio walk instead, so we >>> can easily just modify a single PTE and avoid relying on rmap/mapcounts. >>> >>> We now effectively work on a single PTE instead of multiple PTEs of >>> a large folio, allowing for conversion of individual PTEs from >>> non-exclusive to device-exclusive -- note that the other way always >>> worked on single PTEs. >>> >>> We can drop the MMU_NOTIFY_EXCLUSIVE MMU notifier call and document why >>> that is not required: GUP will already take care of the >>> MMU_NOTIFY_EXCLUSIVE call if required (there is already a device-exclusive >>> entry) when not finding a present PTE and having to trigger a fault and >>> ending up in remove_device_exclusive_entry(). >> >> I will have to look at this a bit more closely tomorrow but this doesn't seem >> right to me. We may be transitioning from a present PTE (ie. a writable >> anonymous mapping) to a non-present PTE (ie. a device-exclusive entry) and >> therefore any secondary processors (eg. other GPUs, iommus, etc.) will need to >> update their copies of the PTE. So I think the notifier call is needed. > > Then it is all very confusing: > > "MMU_NOTIFY_EXCLUSIVE: to signal a device driver that the device will no > longer have exclusive access to the page." > > That's simply not true in the scenario you describe, because nobody had > exclusive access. > > But what you are saying is, that we need to inform others (e.g., KVM) > that we are converting it to a device-exclusive entry, such that they > stop accessing it. > > That makes sense to me (and the cleanup patch in the cleanup series > would have to go as well to prevent the livelock). > > So we would have to update the documentation of MMU_NOTIFY_EXCLUSIVE > that it is also trigger on conversion from non-exclusive to exclusive. > > Does that make sense? Something like that on top: diff --git a/mm/rmap.c b/mm/rmap.c index 49ffac6d27f8..fd6dfe67ce7b 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2405,6 +2405,7 @@ void try_to_migrate(struct folio *folio, enum ttu_flags flags) struct page *make_device_exclusive(struct mm_struct *mm, unsigned long addr, void *owner, struct folio **foliop) { + struct mmu_notifier_range range; struct folio *folio, *fw_folio; struct vm_area_struct *vma; struct folio_walk fw; @@ -2413,6 +2414,7 @@ struct page *make_device_exclusive(struct mm_struct *mm, unsigned long addr, pte_t swp_pte; mmap_assert_locked(mm); + addr = PAGE_ALIGN_DOWN(addr); /* * Fault in the page writable and try to lock it; note that if the @@ -2440,6 +2442,14 @@ struct page *make_device_exclusive(struct mm_struct *mm, unsigned long addr, return ERR_PTR(-EBUSY); } + /* + * Inform secondary MMUs that we are going to convert this PTE to + * device-exclusive, such that they unmap it now. + */ + mmu_notifier_range_init_owner(&range, MMU_NOTIFY_EXCLUSIVE, 0, + mm, addr, addr + PAGE_SIZE, owner); + mmu_notifier_invalidate_range_start(&range); + /* * Let's do a second walk and make sure we still find the same page * mapped writable. If we don't find what we expect, we will trigger @@ -2452,6 +2462,7 @@ struct page *make_device_exclusive(struct mm_struct *mm, unsigned long addr, fw.level != FW_LEVEL_PTE || !pte_write(fw.pte)) { if (fw_folio) folio_walk_end(&fw, vma); + mmu_notifier_invalidate_range_end(&range); folio_unlock(folio); folio_put(folio); return ERR_PTR(-EBUSY); @@ -2485,6 +2496,7 @@ struct page *make_device_exclusive(struct mm_struct *mm, unsigned long addr, folio_remove_rmap_pte(folio, page, vma); folio_walk_end(&fw, vma); + mmu_notifier_invalidate_range_end(&range); *foliop = folio; return page; } -- Cheers, David / dhildenb