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 54887C02181 for ; Mon, 20 Jan 2025 19:00:03 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D93106B008A; Mon, 20 Jan 2025 14:00:02 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id D42686B008C; Mon, 20 Jan 2025 14:00:02 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BE25F280002; Mon, 20 Jan 2025 14:00:02 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 976CC6B008A for ; Mon, 20 Jan 2025 14:00:02 -0500 (EST) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 4E0B01A0258 for ; Mon, 20 Jan 2025 19:00:02 +0000 (UTC) X-FDA: 83028745044.19.3C9BFD8 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf11.hostedemail.com (Postfix) with ESMTP id C4CD440014 for ; Mon, 20 Jan 2025 18:59:59 +0000 (UTC) Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=BuyA3Wc7; spf=pass (imf11.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 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=1737399600; 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=Pf/+pmtSEcW2J86C8PhnSXcNEKOxqEuzriHaKO+xXPk=; b=pLcA00A62q0mkpF7a7AEgaM5/OJPbDiWQIyNjuxDOxvA8/LznI6KJDn2aC+7rimVgTdFqJ 2O0sXQeVeCp+jnNQQHg0D61WOAHEjSnvpT1zAsvPhuLVoKHrE18AIB5u/ON5FL7LR6Okrg CA3SbY/7HcNhoePeDSQ1V6GmC9/6iGk= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=BuyA3Wc7; spf=pass (imf11.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1737399600; a=rsa-sha256; cv=none; b=A9LHAqA3TQk0sNCYXX98k7Q53mjqD1/fnQefAELHtQGP0/SdRTGJJ+DeSJOCU9tLLQ0ZhN gPjKr3q/qkSrB+70xuZY33nZEQmVHjL0lxku8O71x+KqFyUzA2dpCkGuTVSWSXvbDL0lIx k5BO02tAi5jjR8uz/W29Mn2y3w2xA8A= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1737399599; 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=Pf/+pmtSEcW2J86C8PhnSXcNEKOxqEuzriHaKO+xXPk=; b=BuyA3Wc7nf2cKAXbDWXz5VMqyjJs/hX/vDXcLNRT2j15Ou6oNSzHgB4F6geF+zql0xatX1 ATOKbSVv5WPsD8jebGRBqHcC9HMrs/OGj5Vi5UTa1twHFyTa/zA/qzRGg88OeYwdByHmTQ UN2xEIPPpLuOOJsR5I0DgMOAlktGP4k= 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-428-zaNJ53_CMiqKQPgayvYK3w-1; Mon, 20 Jan 2025 13:59:57 -0500 X-MC-Unique: zaNJ53_CMiqKQPgayvYK3w-1 X-Mimecast-MFC-AGG-ID: zaNJ53_CMiqKQPgayvYK3w Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-4362552ce62so24972775e9.0 for ; Mon, 20 Jan 2025 10:59:57 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1737399596; x=1738004396; 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=Pf/+pmtSEcW2J86C8PhnSXcNEKOxqEuzriHaKO+xXPk=; b=PoqNLQpBMHGk6dpzXQsOT94a1PxCY+JU3H1H3xDdKyjPjXNrf4V2QJ6t1Evl2Qt3Bv 7eRT7zOQ8tgD/dN9Mu7ILkMOI/b30WhLSxEg0M6jpST4nmjid93xV1i9iymb005HdAD/ M43uZ0sFL+RpevWVSTqX/2tVDIF/C9zAR/wsN+X1R4hrupozaV4HFNz+XqlrS/cAo5v5 qGOD+KYVpScjbcaapf3XKD28/o9mpzn6EDLXSDuTikw5lRGe1Sctb+ET4SCqejKYSY+N 6sueB8Qs4FqdES052RHCzNa5DPyu3iF9jNCiiPLNTFNEMvsrsojP84SDiXDpyLHUom2Q jgNg== X-Forwarded-Encrypted: i=1; AJvYcCVUBb+Sv0d0VOwO+XLHqkaBHiJwdk2VdAi7gC0uFqxtIiaARvt+KMAWhrCdPPq2RsAdoLBZHJja6Q==@kvack.org X-Gm-Message-State: AOJu0YyuV4MzIlFeS+pQq00Mg2rC2cEJJbKv86I1Q2+BBN5bsnNbLsHF cwI05hQv/Deqh8y43BLRlYm/koMjKkt4m+DqHBIsfUDWV83I9nqi723mdkcxadarkMt4DOZWEuI iJbd3CJDZftE0c3cCMkHS6WF0nVy/F4Uj1+nqAogjfwMmLNxK X-Gm-Gg: ASbGnctCS9OkuzRwOQfjpZ/oVvNlZPufErvasX3R2FVKA23PW1YXQR5JB+cy1k5XTid Svrsz8eUt1gjXfugZwiNYjjghH9rH5PG7/dVZG5JjeMtocK3NkF4FzjFV934QFe1JX+0ti63Flf kYnGl+l6RSo3a3784sreSlF+TlvRy1zgzWpiwag6WZwG7llzvqnU0nWCwi20bbch/XOkZFXckDw ed+NIIHuxKqy5jOObWCVfEkNC4GtAqVHwX1nrfS+IBl33Ag3whikkzO0lcLzJ7VJxI0gGn4Zxa6 0uCFtsYZkYRPFbBSQ1f2rtm/qOZJN0x3JtsVmUScJaU4mhmptMO2EDCsTz00Dr27Lza/lZjnwbD miRLsouR/KUHt5AeyaEMaug== X-Received: by 2002:a05:600c:510c:b0:434:a1e7:27b0 with SMTP id 5b1f17b1804b1-438913ccd4amr166011745e9.11.1737399595735; Mon, 20 Jan 2025 10:59:55 -0800 (PST) X-Google-Smtp-Source: AGHT+IH+TPy54/lS3UFFrnmG1O7DZZp3fmFAErUo+YtByu8LHirZNl4hbvPpqLOD+qxS2Tc6vW5HSw== X-Received: by 2002:a05:600c:510c:b0:434:a1e7:27b0 with SMTP id 5b1f17b1804b1-438913ccd4amr166011455e9.11.1737399595303; Mon, 20 Jan 2025 10:59:55 -0800 (PST) Received: from ?IPV6:2003:cb:c72e:e400:431d:9c08:5611:693c? (p200300cbc72ee400431d9c085611693c.dip0.t-ipconnect.de. [2003:cb:c72e:e400:431d:9c08:5611:693c]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38bf327decbsm11436866f8f.90.2025.01.20.10.59.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 20 Jan 2025 10:59:54 -0800 (PST) Message-ID: Date: Mon, 20 Jan 2025 19:59:52 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RESEND PATCH] fs: avoid mmap sem relocks when coredumping with many missing pages To: Mateusz Guzik , brauner@kernel.org Cc: viro@zeniv.linux.org.uk, jack@suse.cz, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, tavianator@tavianator.com, linux-mm@kvack.org, akpm@linux-foundation.org References: <20250119103205.2172432-1-mjguzik@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: <20250119103205.2172432-1-mjguzik@gmail.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 1SSzbKJYoNsssNWJYkv-m07S8Z8zGU8u2JzPfk-oVaU_1737399596 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: rspam07 X-Rspamd-Queue-Id: C4CD440014 X-Stat-Signature: odmef445qjzp4snyhyk1q7ifis519oox X-Rspam-User: X-HE-Tag: 1737399599-76237 X-HE-Meta: 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 7bLTWa1O 6jQAZggBV502BmNIKqQTVx/2yaYhi99jFRvkjS23vge7BPc1RH6I/3ZuRjzwhbilCKFje3s9mGtVDCL7Zajx/rqR4UXz5h9E+4hSZxevRUM4ErLaVWm/yD3kRrwkJDbAWXz9FDkXV4BzViQGsdtjML9paA8Kv1wL76XVV3iytf6D8hj1ZKGWBobUwHRFSfgkzAjGntGAXkwoNsp8QM4DRhobRgXLm0QCKVswQe4nXzY4rgCk9/KjUJmmxDZ/Fyz09rEF3cbpsM68HBD7W3L+Fl4VLAiLSbnNQpYohZgww+KU4f8ooULO65dn7hoR9XcG966WdOYuvvwh8Huczxoy5sEhCxa6ejw9quhhm3FyXTpqk7DIxrSi5k4QayTgb5WC1MjJxzO9NbK68s99b2FNnH5UbNpusY5YVJzMMHIMSN2srdxSN+v1CId6v8e+zUFnvgDPXLLwPkqMFIzbMjAUHHvn3og== 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 19.01.25 11:32, Mateusz Guzik wrote: > Dumping processes with large allocated and mostly not-faulted areas is > very slow. > > Borrowing a test case from Tavian Barnes: > > int main(void) { > char *mem = mmap(NULL, 1ULL << 40, PROT_READ | PROT_WRITE, > MAP_ANONYMOUS | MAP_NORESERVE | MAP_PRIVATE, -1, 0); > printf("%p %m\n", mem); > if (mem != MAP_FAILED) { > mem[0] = 1; > } > abort(); > } > > That's 1TB of almost completely not-populated area. > > On my test box it takes 13-14 seconds to dump. > > The profile shows: > - 99.89% 0.00% a.out > entry_SYSCALL_64_after_hwframe > do_syscall_64 > syscall_exit_to_user_mode > arch_do_signal_or_restart > - get_signal > - 99.89% do_coredump > - 99.88% elf_core_dump > - dump_user_range > - 98.12% get_dump_page > - 64.19% __get_user_pages > - 40.92% gup_vma_lookup > - find_vma > - mt_find > 4.21% __rcu_read_lock > 1.33% __rcu_read_unlock > - 3.14% check_vma_flags > 0.68% vma_is_secretmem > 0.61% __cond_resched > 0.60% vma_pgtable_walk_end > 0.59% vma_pgtable_walk_begin > 0.58% no_page_table > - 15.13% down_read_killable > 0.69% __cond_resched > 13.84% up_read > 0.58% __cond_resched > > Almost 29% of the time is spent relocking the mmap semaphore between > calls to get_dump_page() which find nothing. > > Whacking that results in times of 10 seconds (down from 13-14). > > While here make the thing killable. > > The real problem is the page-sized iteration and the real fix would > patch it up instead. It is left as an exercise for the mm-familiar > reader. > > Signed-off-by: Mateusz Guzik > --- > > Minimally tested, very plausible I missed something. > > sent again because the previous thing has myself in To -- i failed to > fix up the oneliner suggested by lore.kernel.org. it seem the original > got lost. > > arch/arm64/kernel/elfcore.c | 3 ++- > fs/coredump.c | 38 +++++++++++++++++++++++++++++++------ > include/linux/mm.h | 2 +- > mm/gup.c | 5 ++--- > 4 files changed, 37 insertions(+), 11 deletions(-) > MM side LGTM Acked-by: David Hildenbrand -- Cheers, David / dhildenb