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 X-Spam-Level: X-Spam-Status: No, score=-6.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7CA32C433E7 for ; Thu, 15 Oct 2020 09:01:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1AB362222E for ; Thu, 15 Oct 2020 09:01:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="XhKFqbAE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388583AbgJOJBR (ORCPT ); Thu, 15 Oct 2020 05:01:17 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:47177 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387810AbgJOJBQ (ORCPT ); Thu, 15 Oct 2020 05:01:16 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1602752474; 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=9EDFsxpwcxC951vEAEF+TMmq/CNmoquc1R9sCp6Po3M=; b=XhKFqbAEFs1hMYmCJOArdrfdXwuHS7d8zvVR93owj20d5tGTCHcpHWz4+mio6BOTFRwHXu 561vcRUa0kj6IVHdJfDbxjCRIu1iT0Q3ZhoMsTSK7Wv2szBcjJL2L/n07wOJWqHcOi1AwE FM7f/GVpJSJLRjk3bvS+VtsOuOUUIJ8= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-41-n0F5IPgnORq-n62lM0ttrA-1; Thu, 15 Oct 2020 05:01:12 -0400 X-MC-Unique: n0F5IPgnORq-n62lM0ttrA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 35A1A803629; Thu, 15 Oct 2020 09:01:10 +0000 (UTC) Received: from [10.36.114.207] (ovpn-114-207.ams2.redhat.com [10.36.114.207]) by smtp.corp.redhat.com (Postfix) with ESMTP id 18773100238C; Thu, 15 Oct 2020 09:01:03 +0000 (UTC) Subject: Re: cgroup and FALLOC_FL_PUNCH_HOLE: WARNING: CPU: 13 PID: 2438 at mm/page_counter.c:57 page_counter_uncharge+0x4b/0x5 From: David Hildenbrand To: Mike Kravetz , Mina Almasry Cc: "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , Michal Privoznik , "Michael S. Tsirkin" , Michal Hocko , Muchun Song , "Aneesh Kumar K.V" , Tejun Heo , KVM References: <563d1eef-b780-835a-ebf0-88ae111b20c2@redhat.com> <65a1946f-dbf9-5767-5b51-9c1b786051d1@redhat.com> <5f196069-8b98-0ad3-55e8-19af03d715cd@oracle.com> <32ea3107-b1bc-f39e-3cf8-f6ef427235ef@redhat.com> <075968b6-9e2e-b625-8dc1-a7e5ed0bfd71@redhat.com> Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= mQINBFXLn5EBEAC+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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABtCREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT6JAlgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW 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/mWutNPt95w9wSsUyATLmtNrwccz63W5Ag0EVcufkQEQAOfX3n0g0fZz 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+w6DABEBAAGJAjwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/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 GmbH Message-ID: <69b8b3a2-fa3a-394f-2659-10a7170ac616@redhat.com> Date: Thu, 15 Oct 2020 11:01:03 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <075968b6-9e2e-b625-8dc1-a7e5ed0bfd71@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 15.10.20 10:57, David Hildenbrand wrote: > On 15.10.20 09:56, David Hildenbrand wrote: >> On 14.10.20 20:31, Mike Kravetz wrote: >>> On 10/14/20 11:18 AM, David Hildenbrand wrote: >>>> On 14.10.20 19:56, Mina Almasry wrote: >>>>> On Wed, Oct 14, 2020 at 9:15 AM David Hildenbrand wrote: >>>>>> >>>>>> On 14.10.20 17:22, David Hildenbrand wrote: >>>>>>> Hi everybody, >>>>>>> >>>>>>> Michal Privoznik played with "free page reporting" in QEMU/virtio-balloon >>>>>>> with hugetlbfs and reported that this results in [1] >>>>>>> >>>>>>> 1. WARNING: CPU: 13 PID: 2438 at mm/page_counter.c:57 page_counter_uncharge+0x4b/0x5 >>>>>>> >>>>>>> 2. Any hugetlbfs allocations failing. (I assume because some accounting is wrong) >>>>>>> >>>>>>> >>>>>>> QEMU with free page hinting uses fallocate(FALLOC_FL_PUNCH_HOLE) >>>>>>> to discard pages that are reported as free by a VM. The reporting >>>>>>> granularity is in pageblock granularity. So when the guest reports >>>>>>> 2M chunks, we fallocate(FALLOC_FL_PUNCH_HOLE) one huge page in QEMU. >>>>>>> >>>>>>> I was also able to reproduce (also with virtio-mem, which similarly >>>>>>> uses fallocate(FALLOC_FL_PUNCH_HOLE)) on latest v5.9 >>>>>>> (and on v5.7.X from F32). >>>>>>> >>>>>>> Looks like something with fallocate(FALLOC_FL_PUNCH_HOLE) accounting >>>>>>> is broken with cgroups. I did *not* try without cgroups yet. >>>>>>> >>>>>>> Any ideas? >>>>> >>>>> Hi David, >>>>> >>>>> I may be able to dig in and take a look. How do I reproduce this >>>>> though? I just fallocate(FALLOC_FL_PUNCH_HOLE) one 2MB page in a >>>>> hugetlb region? >>>>> >>>> >>>> Hi Mina, >>>> >>>> thanks for having a look. I started poking around myself but, >>>> being new to cgroup code, I even failed to understand why that code gets >>>> triggered though the hugetlb controller isn't even enabled. >>>> >>>> I assume you at least have to make sure that there is >>>> a page populated (MMAP_POPULATE, or read/write it). But I am not >>>> sure yet if a single fallocate(FALLOC_FL_PUNCH_HOLE) is >>>> sufficient, or if it will require a sequence of >>>> populate+discard(punch) (or multi-threading). >>> >>> FWIW - I ran libhugetlbfs tests which do a bunch of hole punching >>> with (and without) hugetlb controller enabled and did not see this issue. >>> >>> May need to reproduce via QEMU as below. >> >> Not sure if relevant, but QEMU should be using >> memfd_create(MFD_HUGETLB|MFD_HUGE_2MB) to obtain a hugetlbfs file. >> >> Also, QEMU fallocate(FALLOC_FL_PUNCH_HOLE)'s a significant of memory of >> the md (e.g., > 90%). >> > > I just tried to reproduce by doing random accesses + random fallocate(FALLOC_FL_PUNCH_HOLE) within a file - without success. > > So could be > 1. KVM is involved messing this up > 2. Multi-threading is involved > Able to reproduce with TCG under QEMU, so not a KVM issue. -- Thanks, David / dhildenb