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 AB033C27C4F for ; Fri, 21 Jun 2024 09:18:33 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 06E396B04AB; Fri, 21 Jun 2024 05:18:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 01DD16B04AC; Fri, 21 Jun 2024 05:18:32 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DB2896B04AD; Fri, 21 Jun 2024 05:18:32 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id AF4F56B04AB for ; Fri, 21 Jun 2024 05:18:32 -0400 (EDT) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 54EB01A0C4F for ; Fri, 21 Jun 2024 09:18:32 +0000 (UTC) X-FDA: 82254345264.08.BA15CAC Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf21.hostedemail.com (Postfix) with ESMTP id 185111C0013 for ; Fri, 21 Jun 2024 09:18:29 +0000 (UTC) Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=QrvArpCu; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf21.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1718961498; 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=fmNKGBn/d/UHImXCWFCHyqNE5ol7HkHGQOjWdhN4Z6U=; b=8UN22BfO54SlQcIgQFVgjRiCzO13saSJSxHw0ie+m1oN51LdeGXtT2hX+25J/+Ee9Hg+ru xDTqc0aEWL82w6WhkguYdomHvbey86Y7Y7jGAwsZeqEuhM1OcPpO6N/lF/F0Zvpx+8ALwK rzg1E0RJ9ZB6x46XWmFz3TMcltfmAgc= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1718961498; a=rsa-sha256; cv=none; b=53pY5TAfICX6v3L2nyOAR/ccDltjcgN+iRxSIsLb/niaUb2IP3biP+SG+Ch04NXMOmQRsL dYr+nvTvDrhmTlRqCYipc2TVRWZqYGD38TVICp9gDM2rb5b9XHb679QncFcj0azoYD+7s5 eqz9JrQTnAEBSXjPxispIZLX4g5usnU= ARC-Authentication-Results: i=1; imf21.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=QrvArpCu; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf21.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1718961509; 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=fmNKGBn/d/UHImXCWFCHyqNE5ol7HkHGQOjWdhN4Z6U=; b=QrvArpCu1iCeuIIUyZfvASnCptAyFGPZ25ZDXXMWUmNPNF/H4bMj7vh/tVqv9THMSimcew QWpLTrmN0ZxnLyjNZg5AcN4RJL1tBC9PyYyUejFnkf9wtmIc6Pp58lbbqEmu9FL8V4V8CA psbvwKmHxGCMgYPR7URWXEDlLonLS6w= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-312-O_-_pUS9MnO1yx4QHdqhwQ-1; Fri, 21 Jun 2024 05:18:27 -0400 X-MC-Unique: O_-_pUS9MnO1yx4QHdqhwQ-1 Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-4210d151c5bso14632165e9.3 for ; Fri, 21 Jun 2024 02:18:27 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1718961506; x=1719566306; 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=fmNKGBn/d/UHImXCWFCHyqNE5ol7HkHGQOjWdhN4Z6U=; b=h1m0EhwPfRIBAWrP9Ui2zK8M7SJqAEXr0Ea3G4XZZlutEzQFWtO0TVNM9tPfvt56W6 hbCIRW4AhEYWLo3Yz/Dp9TUY7lHZrsfu7TM97FbtrxLSkixD8NMQUEIHhVwYc5jxlYfI PopqdPqhUX4+F4YA90rNiClSCDBmwaPNPMjAwHdHxqsYsg7AkpcoFOlbG1RVCrzIJ1Vm kZqZiN8vgQFQDeg9Vi+0P9621tX10sYX172m5AW6OShjaUYuD3IXdPJDDzeDA7TcqP11 Nfyg+qKArcFdOGQdWxEko2WER4UWVkm3o6wBmqEyg2BIrIb9EhDd+TDC+bjbdsRDS9sI 7Blw== X-Forwarded-Encrypted: i=1; AJvYcCU36zCXkHHQOgxBoFtDgao4tFbnO/YY8D4fV12G0hf/+I6ta5RdXVeG8aP2ijiGgWQPsGJNN9jvcP5FuYWKkeNtMbM= X-Gm-Message-State: AOJu0Yy/+OBVZ+N7ctjE63hvevNyEMZFyPH1EA1cviWDDSDqyUUnn9V2 JpfP1bPncebQo4bijTNwEtbyT7moIaPA3UdXjEMf8AMrCIxpeHbeU2XrtLCDmfpWIcF10ij6c3/ EKwgdFxbHWJ+Wj3ll4UqPRSVF2fWTE9z4glnGFT1dXRHiafoy X-Received: by 2002:a05:600c:4c24:b0:424:7e0c:68e2 with SMTP id 5b1f17b1804b1-4247e0c6af1mr29679975e9.12.1718961506146; Fri, 21 Jun 2024 02:18:26 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHgvSRVkeQNmVImikLIebQnTxOpk6aC8WiXLcRaMoHwYaeVj2QwsTFG2DI7PeorMsbIv6fCpg== X-Received: by 2002:a05:600c:4c24:b0:424:7e0c:68e2 with SMTP id 5b1f17b1804b1-4247e0c6af1mr29679755e9.12.1718961505702; Fri, 21 Jun 2024 02:18:25 -0700 (PDT) Received: from [192.168.3.141] (p4ff2358f.dip0.t-ipconnect.de. [79.242.53.143]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4248191116fsm19727005e9.37.2024.06.21.02.18.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 21 Jun 2024 02:18:25 -0700 (PDT) Message-ID: <02b87f01-69c9-4007-b0d0-5ce9ce35876d@redhat.com> Date: Fri, 21 Jun 2024 11:18:24 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/3] mm: use folio_add_new_anon_rmap() if folio_test_anon(folio)==false To: Barry Song <21cnbao@gmail.com> Cc: akpm@linux-foundation.org, linux-mm@kvack.org, baolin.wang@linux.alibaba.com, chrisl@kernel.org, linux-kernel@vger.kernel.org, mhocko@suse.com, ryan.roberts@arm.com, shy828301@gmail.com, surenb@google.com, v-songbaohua@oppo.com, willy@infradead.org, ying.huang@intel.com, yosryahmed@google.com, yuzhao@google.com, Shuai Yuan References: <20240617231137.80726-1-21cnbao@gmail.com> <20240617231137.80726-3-21cnbao@gmail.com> <60a075da-7c7e-4d99-ac52-059e5a17b72e@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: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 185111C0013 X-Stat-Signature: ap5szc1xi9h9fj6dtsuzjiw8nb6pdpuz X-Rspam-User: X-HE-Tag: 1718961509-480307 X-HE-Meta: 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 /SRHnBtB 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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 20.06.24 11:59, Barry Song wrote: > On Thu, Jun 20, 2024 at 8:49 PM David Hildenbrand wrote: >> >> On 20.06.24 10:33, Barry Song wrote: >>> On Thu, Jun 20, 2024 at 7:46 PM David Hildenbrand wrote: >>>> >>>> On 18.06.24 01:11, Barry Song wrote: >>>>> From: Barry Song >>>>> >>>>> For the !folio_test_anon(folio) case, we can now invoke folio_add_new_anon_rmap() >>>>> with the rmap flags set to either EXCLUSIVE or non-EXCLUSIVE. This action will >>>>> suppress the VM_WARN_ON_FOLIO check within __folio_add_anon_rmap() while initiating >>>>> the process of bringing up mTHP swapin. >>>>> >>>>> static __always_inline void __folio_add_anon_rmap(struct folio *folio, >>>>> struct page *page, int nr_pages, struct vm_area_struct *vma, >>>>> unsigned long address, rmap_t flags, enum rmap_level level) >>>>> { >>>>> ... >>>>> if (unlikely(!folio_test_anon(folio))) { >>>>> VM_WARN_ON_FOLIO(folio_test_large(folio) && >>>>> level != RMAP_LEVEL_PMD, folio); >>>>> } >>>>> ... >>>>> } >>>>> >>>>> It also improves the code’s readability. Currently, all new anonymous >>>>> folios calling folio_add_anon_rmap_ptes() are order-0. This ensures >>>>> that new folios cannot be partially exclusive; they are either entirely >>>>> exclusive or entirely shared. >>>>> >>>>> Suggested-by: David Hildenbrand >>>>> Signed-off-by: Barry Song >>>>> Tested-by: Shuai Yuan >>>>> --- >>>>> mm/memory.c | 8 ++++++++ >>>>> mm/swapfile.c | 13 +++++++++++-- >>>>> 2 files changed, 19 insertions(+), 2 deletions(-) >>>>> >>>>> diff --git a/mm/memory.c b/mm/memory.c >>>>> index 1f24ecdafe05..620654c13b2f 100644 >>>>> --- a/mm/memory.c >>>>> +++ b/mm/memory.c >>>>> @@ -4339,6 +4339,14 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) >>>>> if (unlikely(folio != swapcache && swapcache)) { >>>>> folio_add_new_anon_rmap(folio, vma, address, RMAP_EXCLUSIVE); >>>>> folio_add_lru_vma(folio, vma); >>>>> + } else if (!folio_test_anon(folio)) { >>>>> + /* >>>>> + * We currently only expect small !anon folios, for which we now >>>>> + * that they are either fully exclusive or fully shared. If we >>>>> + * ever get large folios here, we have to be careful. >>>>> + */ >>>>> + VM_WARN_ON_ONCE(folio_test_large(folio)); >>>>> + folio_add_new_anon_rmap(folio, vma, address, rmap_flags); >>>>> } else { >>>>> folio_add_anon_rmap_ptes(folio, page, nr_pages, vma, address, >>>>> rmap_flags); >>>>> diff --git a/mm/swapfile.c b/mm/swapfile.c >>>>> index ae1d2700f6a3..69efa1a57087 100644 >>>>> --- a/mm/swapfile.c >>>>> +++ b/mm/swapfile.c >>>>> @@ -1908,8 +1908,17 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, >>>>> VM_BUG_ON_FOLIO(folio_test_writeback(folio), folio); >>>>> if (pte_swp_exclusive(old_pte)) >>>>> rmap_flags |= RMAP_EXCLUSIVE; >>>>> - >>>>> - folio_add_anon_rmap_pte(folio, page, vma, addr, rmap_flags); >>>>> + /* >>>>> + * We currently only expect small !anon folios, for which we now that >>>>> + * they are either fully exclusive or fully shared. If we ever get >>>>> + * large folios here, we have to be careful. >>>>> + */ >>>>> + if (!folio_test_anon(folio)) { >>>>> + VM_WARN_ON_ONCE(folio_test_large(folio)); >>>> >>>> (comment applies to both cases) >>>> >>>> Thinking about Hugh's comment, we should likely add here: >>>> >>>> VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio); >>>> >>>> [the check we are removing from __folio_add_anon_rmap()] >>>> >>>> and document for folio_add_new_anon_rmap() in patch #1, that when >>>> dealing with folios that might be mapped concurrently by others, the >>>> folio lock must be held. >>> >>> I assume you mean something like the following for patch#1? >>> >>> diff --git a/mm/rmap.c b/mm/rmap.c >>> index df1a43295c85..20986b25f1b2 100644 >>> --- a/mm/rmap.c >>> +++ b/mm/rmap.c >>> @@ -1394,7 +1394,8 @@ void folio_add_anon_rmap_pmd(struct folio >>> *folio, struct page *page, >>> * >>> * Like folio_add_anon_rmap_*() but must only be called on *new* folios. >>> * This means the inc-and-test can be bypassed. >>> - * The folio does not have to be locked. >>> + * The folio doesn't necessarily need to be locked while it's >>> exclusive unless two threads >>> + * map it concurrently. However, the folio must be locked if it's shared. >>> * >>> * If the folio is pmd-mappable, it is accounted as a THP. >>> */ >>> @@ -1406,6 +1407,7 @@ void folio_add_new_anon_rmap(struct folio >>> *folio, struct vm_area_struct *vma, >>> int nr_pmdmapped = 0; >>> >>> VM_WARN_ON_FOLIO(folio_test_hugetlb(folio), folio); >>> + VM_WARN_ON_FOLIO(!exclusive && !folio_test_locked(folio), folio); >> >> For now this would likely do. I was concerned about a concurrent >> scenario in the exclusive case, but that shouldn't really happen I guess. >> > > Since this is primarily a documentation update, I'll wait for two or > three days to see if > there are any more Linux-next reports before sending v3 combining these fixes > together(I've already fixed another doc warn reported by lkp) and seek Andrew's > assistance to drop v2 and apply v3. Feel free to send fixup patches for such small stuff (for example, as reply to this mail). Usually, no need for a new series. Andrew will squash all fixups before merging it to mm-stable. -- Cheers, David / dhildenb