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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6BBA6C10DC1 for ; Mon, 4 Dec 2023 17:59:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230489AbjLDR7i (ORCPT ); Mon, 4 Dec 2023 12:59:38 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39002 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229659AbjLDR7g (ORCPT ); Mon, 4 Dec 2023 12:59:36 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 89F429A for ; Mon, 4 Dec 2023 09:59:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1701712781; 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=y/n3XETFOZPx/XYOME4s/DOGADFc/e3GNu9UPa/MpLQ=; b=bBLGQVAdLnONkT+70vZu+M62KpObm5rEiuZvbTTLFBPWY+SsDaR3NXktoFocfI2BRfzxUY 7aRnnf0pRjzNoVLOV4Fd89V2v9Llg0ZxZ63AFLsTbD04fK6Uvbz5PDVAavu+nqayLy0HO1 svJ7kvoAe2ZtBNQegSRZS6zIvvoN0/g= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-97-ffLt5CB5MfiV7s8tqbF5lg-1; Mon, 04 Dec 2023 12:59:40 -0500 X-MC-Unique: ffLt5CB5MfiV7s8tqbF5lg-1 Received: by mail-wr1-f69.google.com with SMTP id ffacd0b85a97d-333354a9242so1179559f8f.1 for ; Mon, 04 Dec 2023 09:59:39 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701712779; x=1702317579; h=content-transfer-encoding:in-reply-to:organization:autocrypt:from :references:cc:to:content-language:subject:user-agent:mime-version :date:message-id:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=y/n3XETFOZPx/XYOME4s/DOGADFc/e3GNu9UPa/MpLQ=; b=rG5Fcbzf0KpUSvp19I5mfelapLP6GMSFAX7QlR4Zf45s/SiZ3PWSssNW4Q35TJtgTm OtAIJolmvc568h7Xp/SiYVYnpI9QALclzLMr8d65Srqb8BfNgmzV9MzvIw579v02D1+U N60oChc6a5+CtZVXJzUpCfsubDo2YLRgs/OS3tJXyS4gTLnXuo9ImhH3cRdNiGC5tNDe 8hmneGT93MnXD3v7qEXQ1iKdz26T5/+fzHx4eyW40y0/LuxdNIGeyVSqBkJDKx/sB7jW 4XPFyqCdc3uOq/HhKT92LN2ihOT2rsNTS3f01O55fwZ3gMKUoMKL0xazcs16KezhlXpx 4V1g== X-Gm-Message-State: AOJu0YxHmQtL0pr44RWmFRt82bsgzkE/SFaRPiV36AYYBj4bRiizB6W3 5HH4JiHc1XFwDdkP08c7jsHAg05f5IbdQtqpwmJy+OajOE7vsKsLGSNQeFSvLqLduhotKYHC6Zy Liw4/ZisTxWV1H2LhlxBq5YGPd8nl9BLt+lkIBgEwfoAJCs/bFqa39c+Mo4HtsYgXEsGpKK4RF7 iJXCwk X-Received: by 2002:a05:600c:a0a:b0:40b:5e56:7b5d with SMTP id z10-20020a05600c0a0a00b0040b5e567b5dmr3150309wmp.166.1701712778926; Mon, 04 Dec 2023 09:59:38 -0800 (PST) X-Google-Smtp-Source: AGHT+IHt/l7AeQDswbm7Ci4IBH0mEfB75rib92wPfAuefYCyEyivuiO0RMgqmbHbUiO4LvRSUXDLCQ== X-Received: by 2002:a05:600c:a0a:b0:40b:5e56:7b5d with SMTP id z10-20020a05600c0a0a00b0040b5e567b5dmr3150290wmp.166.1701712778457; Mon, 04 Dec 2023 09:59:38 -0800 (PST) Received: from ?IPV6:2003:cb:c722:3700:6501:8925:6f9:fcdc? (p200300cbc72237006501892506f9fcdc.dip0.t-ipconnect.de. [2003:cb:c722:3700:6501:8925:6f9:fcdc]) by smtp.gmail.com with ESMTPSA id u8-20020a05600c19c800b004030e8ff964sm19635029wmq.34.2023.12.04.09.59.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 04 Dec 2023 09:59:38 -0800 (PST) Message-ID: <1120cff5-df34-47ab-86ca-d73887fcba2e@redhat.com> Date: Mon, 4 Dec 2023 18:59:37 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC 34/39] mm/rmap: introduce folio_try_dup_anon_rmap_[pte|ptes|pmd]() Content-Language: en-US To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Andrew Morton , "Matthew Wilcox (Oracle)" , Hugh Dickins , Ryan Roberts , Yin Fengwei , Mike Kravetz , Muchun Song , Peter Xu References: <20231204142146.91437-1-david@redhat.com> <20231204142146.91437-35-david@redhat.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: <20231204142146.91437-35-david@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > -static inline void __page_dup_rmap(struct page *page, bool compound) > +static inline int __folio_try_dup_anon_rmap(struct folio *folio, > + struct page *page, unsigned int nr_pages, > + struct vm_area_struct *src_vma, enum rmap_mode mode) > { > - VM_WARN_ON(folio_test_hugetlb(page_folio(page))); > + int i; > > - if (compound) { > - struct folio *folio = (struct folio *)page; > + VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); > > - VM_BUG_ON_PAGE(compound && !PageHead(page), page); > - atomic_inc(&folio->_entire_mapcount); > - } else { > - atomic_inc(&page->_mapcount); > + /* > + * No need to check+clear for already shared PTEs/PMDs of the folio. > + * This includes PTE mappings of (order-0) KSM folios. > + */ > + if (likely(mode == RMAP_MODE_PTE)) { > + for (i = 0; i < nr_pages; i++) { > + if (PageAnonExclusive(page + i)) > + goto clear; > + } > + } else if (mode == RMAP_MODE_PMD) { > + if (PageAnonExclusive(page)) > + goto clear; > } > + goto dup; > + > +clear: > + /* > + * If this folio may have been pinned by the parent process, > + * don't allow to duplicate the mappings but instead require to e.g., > + * copy the subpage immediately for the child so that we'll always > + * guarantee the pinned folio won't be randomly replaced in the > + * future on write faults. > + */ > + if (likely(!folio_is_device_private(folio) && > + unlikely(folio_needs_cow_for_dma(src_vma, folio)))) > + return -EBUSY; > + > + if (likely(mode == RMAP_MODE_PTE)) { > + for (i = 0; i < nr_pages; i++) > + ClearPageAnonExclusive(page + i); > + } else if (mode == RMAP_MODE_PMD) { > + ClearPageAnonExclusive(page); > + } > + > +dup: > + __folio_dup_rmap(folio, page, nr_pages, mode); > + return 0; Playing with this, I think it can be implemented more efficiently by only looping once and optimizing for the common case that PAE is set. Will have to do some more measurements. -- Cheers, David / dhildenb