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 761D5C4345F for ; Thu, 18 Apr 2024 15:09:51 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DE3716B0088; Thu, 18 Apr 2024 11:09:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D93226B008C; Thu, 18 Apr 2024 11:09:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C33F46B0092; Thu, 18 Apr 2024 11:09:50 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id A60D26B0088 for ; Thu, 18 Apr 2024 11:09:50 -0400 (EDT) Received: from smtpin23.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 499E7A1BDF for ; Thu, 18 Apr 2024 15:09:50 +0000 (UTC) X-FDA: 82022987340.23.06DD0A0 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf27.hostedemail.com (Postfix) with ESMTP id BEE2940005 for ; Thu, 18 Apr 2024 15:09:47 +0000 (UTC) Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Gcrl2TOa; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf27.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=1713452987; 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=vwjfiFQnjjbAD99CHjoCNe/Mj9Dk40lmq8ErGQAJMSo=; b=qG6NxbdJ+JzbV1RxH5elHZjPkDWFpVKHY4txXF23XmdNO7KprvL5H1qjTf9K8HaN1+h1By ZbCNKxTkmbix/A4PnOQ/8RoHgRTWEHPy726h4ELoiSH7KBRv0rl1fLkDxtC7FdFYqvltzo e8o1XVpW6R3/0HXzk5zLvQDNgJ5t2zQ= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Gcrl2TOa; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf27.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1713452987; a=rsa-sha256; cv=none; b=Ojo10Nrsr0a9DbEUJ8AujgFvm0gO1XD4uqeCju4vWwjY2SKWIFaEmrXaJeeIWzvNmRYne4 7prErGlNUgKddy1fLr3NpSv4fuD+amxM7mHMh15x6s/QT5rI5VZ+vy2o6uB/A2JEyqJq/J OQ4SxNumOckSioXNCdp/CMma2Na6AQw= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1713452987; 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=vwjfiFQnjjbAD99CHjoCNe/Mj9Dk40lmq8ErGQAJMSo=; b=Gcrl2TOaZAI23dUqAkxi7v2aircG3m1HsD44L4w8wQUGBTznEVKX50WY+GdVeAHtBQulUY 9QTCYc/zRcOzbSOXe8+ZaGK+ZsQoqr+TpRvp8gUDmGPlSzPT72B7Pw73ZU6CffKr6Icwm5 gXnPbty86MgVGtX3s3e+M/8Baf48Hf4= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-18-7BMHQ0aBMDegqjl1OIwocQ-1; Thu, 18 Apr 2024 11:09:45 -0400 X-MC-Unique: 7BMHQ0aBMDegqjl1OIwocQ-1 Received: by mail-wm1-f71.google.com with SMTP id 5b1f17b1804b1-4147f17da12so5556445e9.0 for ; Thu, 18 Apr 2024 08:09:45 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1713452984; x=1714057784; 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=vwjfiFQnjjbAD99CHjoCNe/Mj9Dk40lmq8ErGQAJMSo=; b=gSp1m+IxcrutJxUb0065LMAmF7zR32KN/XbCOvTGwsrMNvL9ZPc74bkrHhxOzj9q07 keuJGVjDbvNLmbpT6+8F/jQEM7dNyZ1y4OlQePlzP72DegSlkRLLECI3iIjKTYXuN1hV OHTuIUqjVqDpWTjEr0/Cm9ulYhS3QgXNi5iyYX2ai8gD1bq8VoI5WixqHyCTq2CazjTG AyLplrQG1InxJGAD2S7cNSf6Y8Gyqihh97zXPxE/Ttouu1pHpGiCWVcfl2fUc7JE4zzw ZS4r9xNymRCLkgNiPjSSoF8rJPpWePKe1EFtr2oJcMeYCWAZOsy2LwOpkw9HTqkF2t0v XWZg== X-Forwarded-Encrypted: i=1; AJvYcCV85em8m4GzuCdxRykfF1ggltHjYVmo3PJaaaSMCvCWulPSEH8+vJiFDRC4AdtyTxilqW89nUDinjXD0GqhhNvF7d8= X-Gm-Message-State: AOJu0Yz9euGJmlFEI+RcAJCKFHxD/O8PXHMmAiP9KH17ylkHn9VWynRT peSGyauUIVjUmW2b3NVZE+gcALnSNI0G4hoMzRTVIkn154NMDmmIcXOyW7nYMnQDP2zYrAMg2El a4ZL1HPGdHJVY+sTsX9lWtYarnVZc9NiWJ3NXRNbG5ZbwuOd1 X-Received: by 2002:a05:600c:524a:b0:416:3db7:74b4 with SMTP id fc10-20020a05600c524a00b004163db774b4mr2040046wmb.24.1713452984187; Thu, 18 Apr 2024 08:09:44 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFTNhHILxv2DrETC17o2+9HAaRjsk+gWsTIv9PW4hja8gy+K29xAShokS3+g00FJ+3co5c44Q== X-Received: by 2002:a05:600c:524a:b0:416:3db7:74b4 with SMTP id fc10-20020a05600c524a00b004163db774b4mr2040006wmb.24.1713452983695; Thu, 18 Apr 2024 08:09:43 -0700 (PDT) Received: from ?IPV6:2003:cb:c708:4e00:fd61:512:d944:28f6? (p200300cbc7084e00fd610512d94428f6.dip0.t-ipconnect.de. [2003:cb:c708:4e00:fd61:512:d944:28f6]) by smtp.gmail.com with ESMTPSA id hg12-20020a05600c538c00b00415dfa709dasm2976731wmb.15.2024.04.18.08.09.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 18 Apr 2024 08:09:43 -0700 (PDT) Message-ID: Date: Thu, 18 Apr 2024 17:09:41 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 04/18] mm: track mapcount of large folios in single value To: Lance Yang Cc: akpm@linux-foundation.org, cgroups@vger.kernel.org, chris@zankel.net, corbet@lwn.net, dalias@libc.org, fengwei.yin@intel.com, glaubitz@physik.fu-berlin.de, hughd@google.com, jcmvbkbc@gmail.com, linmiaohe@huawei.com, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-sh@vger.kernel.org, linux-trace-kernel@vger.kernel.org, muchun.song@linux.dev, naoya.horiguchi@nec.com, peterx@redhat.com, richardycc@google.com, ryan.roberts@arm.com, shy828301@gmail.com, willy@infradead.org, ysato@users.sourceforge.jp, ziy@nvidia.com References: <20240409192301.907377-5-david@redhat.com> <20240418145003.8780-1-ioworker0@gmail.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: <20240418145003.8780-1-ioworker0@gmail.com> 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: 7bit X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: BEE2940005 X-Rspam-User: X-Stat-Signature: nnjo3wq654qxip75nkkidt46a5u6uyxc X-HE-Tag: 1713452987-993076 X-HE-Meta: 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 PmwVL23v tck6tGmjwnXq50P2c3dkcWisNwLXF3xFM1vb+hqcNoCjFTUhon5vKVQpOZqhpEMDbpp1X+uKSoJEUDXAdGj039EwafrUD/bLvU7pPSmqdeLFORoPqMlkTAwhslQYZGnPAFU0C+0xbzeXSG9bLPxk/UWbjSVEM3OdNU4HuKy0rjTE/e58nlXm9Z7k/u1G7b9ArRvbr9LO9iEUMvGinGwnYfgEe/2VzToHz95w5CVgJ5PXZaLybZs8Gu7UBLKKwou+ejsuCy19jPriNeRGhBaXk6FWe3joNo+ciNEZ8+L56ZhkmHKX9fV/WIXXzataNZN62WMa+QCeV7/cs+ZL2OKj68LgpdAV7YKAZ81o0bS23q5dbRpPmofEJ7Fz51ifGo72p0a3HX7bgJ02W9fmDQ0GFOUmZprSE0FGtsRZxP/TAF9lSAgc= 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 18.04.24 16:50, Lance Yang wrote: > Hey David, > > FWIW, just a nit below. Hi! Thanks, but that was done on purpose. This way, we'll have a memory barrier (due to at least one atomic_inc_and_test()) between incrementing the folio refcount (happening before the rmap change) and incrementing the mapcount. Is it required? Not 100% sure, refcount vs. mapcount checks are always a bit racy. But doing it this way let me sleep better at night ;) [with no subpage mapcounts, we'd do the atomic_inc_and_test on the large mapcount and have the memory barrier there again; but that's stuff for the future] Thanks! > > diff --git a/mm/rmap.c b/mm/rmap.c > index 2608c40dffad..08bb6834cf72 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -1143,7 +1143,6 @@ static __always_inline unsigned int __folio_add_rmap(struct folio *folio, > int *nr_pmdmapped) > { > atomic_t *mapped = &folio->_nr_pages_mapped; > - const int orig_nr_pages = nr_pages; > int first, nr = 0; > > __folio_rmap_sanity_checks(folio, page, nr_pages, level); > @@ -1155,6 +1154,7 @@ static __always_inline unsigned int __folio_add_rmap(struct folio *folio, > break; > } > > + atomic_add(nr_pages, &folio->_large_mapcount); > do { > first = atomic_inc_and_test(&page->_mapcount); > if (first) { > @@ -1163,7 +1163,6 @@ static __always_inline unsigned int __folio_add_rmap(struct folio *folio, > nr++; > } > } while (page++, --nr_pages > 0); > - atomic_add(orig_nr_pages, &folio->_large_mapcount); > break; > case RMAP_LEVEL_PMD: > first = atomic_inc_and_test(&folio->_entire_mapcount); > > Thanks, > Lance > -- Cheers, David / dhildenb