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=-2.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 2248FC1B0E3 for ; Fri, 11 Dec 2020 04:10:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D2A7A23ED2 for ; Fri, 11 Dec 2020 04:10:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2395254AbgLKEJQ (ORCPT ); Thu, 10 Dec 2020 23:09:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34018 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726253AbgLKEIw (ORCPT ); Thu, 10 Dec 2020 23:08:52 -0500 Received: from mail-pf1-x441.google.com (mail-pf1-x441.google.com [IPv6:2607:f8b0:4864:20::441]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 76E14C0613CF; Thu, 10 Dec 2020 20:08:12 -0800 (PST) Received: by mail-pf1-x441.google.com with SMTP id q22so6168942pfk.12; Thu, 10 Dec 2020 20:08:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=Ius18itnGQVstq9bqYZLUwNWbZ8T7njWch6EzxvjPsA=; b=Qd/trmlZE61igq11WRWlvIXhwMKIGAzikr4i85zvqPvP0xZu3RPsj+GWkP7PWqYqbV hKhnyA8nl0zK3Y7gS3Dx3zvWWER5pFfzo10n0asMk/GPUnexwT2IK/zJoFBacHO9n/Gr qY0uY4Fig/b2Z9L00DDx7YKXxXA3X2735Ip1LrYRoq+nh71jxV9PddF7X63i0gI/qF2i 0erYwJVM1aO02gLsEjR9/MHMoO5+KLTyC48+qADFNqfjgc8NgPfE6jgbg0CLKlsNzzGx WUxPoirrrHCK9E4xjQwcYhiYiPRvE/wxzKsEq9ZZdRyEJSPws1mXYkHP2LaT36f+KUDN Fncg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=Ius18itnGQVstq9bqYZLUwNWbZ8T7njWch6EzxvjPsA=; b=YfVxQ4K0dhW81MBw5sy0LpBNEgAKrsklKkmoXUEvLjY9XgMSnpDjrmLetY4Jm7znGa hv/J7OExRnoaMHBdoiwdZrOxwl9p4sh6XJmY7NRR/ea9909u/hZMqrRzJ3tlAnKwupp2 Bd3VrL8WKIThZMo21evvsilc/IryNjiTV3Kc+Ahay1reCTw2u/1XLOJOYVqhTjWXssx7 e1NeXy5hYLCAQpMnU7R1o5tkuHeepcX01FDaPN+xRGxkJ0uKZRg1rvVZWhbnmC3SrPnc DohbX5xJDLnObxzg5MvV3ByNE0oHP7yRWZy46Dpu+gO6Pv1w4hW0IOlbe38/0n4wrE7N FJhQ== X-Gm-Message-State: AOAM533F+D9VGdAO8/FnW/Kda/iDn72osp9tHAhbApT2vnWxjAp2HVZ9 KR5qurC6AHkXShmheoIriyw= X-Google-Smtp-Source: ABdhPJy6X+B1ThgRb512lrgxQUK0VKgDoRZDc0qiKYGrIfhMfxa3FRkxaEj/zY8y9KLjoo8S+hWuzw== X-Received: by 2002:a62:7fc1:0:b029:19f:1dab:5029 with SMTP id a184-20020a627fc10000b029019f1dab5029mr3656993pfd.13.1607659691987; Thu, 10 Dec 2020 20:08:11 -0800 (PST) Received: from localhost ([2401:fa00:8f:203:a6ae:11ff:fe11:4b46]) by smtp.gmail.com with ESMTPSA id b4sm8017019pju.33.2020.12.10.20.08.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Dec 2020 20:08:11 -0800 (PST) Date: Fri, 11 Dec 2020 13:08:07 +0900 From: Sergey Senozhatsky To: Eric Biggers Cc: Sergey Senozhatsky , Greg Kroah-Hartman , Jaegeuk Kim , "Theodore Y. Ts'o" , Suleiman Souhlal , linux-fscrypt@vger.kernel.org, stable@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [stable] ext4 fscrypt_get_encryption_info() circular locking dependency Message-ID: <20201211040807.GF1667627@google.com> References: <20201211033657.GE1667627@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org On (20/12/10 19:48), Eric Biggers wrote: > > > > [ 133.454836] Chain exists of: > > jbd2_handle --> fscrypt_init_mutex --> fs_reclaim > > > > [ 133.454840] Possible unsafe locking scenario: > > > > [ 133.454841] CPU0 CPU1 > > [ 133.454843] ---- ---- > > [ 133.454844] lock(fs_reclaim); > > [ 133.454846] lock(fscrypt_init_mutex); > > [ 133.454848] lock(fs_reclaim); > > [ 133.454850] lock(jbd2_handle); > > [ 133.454851] > > This actually got fixed by the patch series > https://lkml.kernel.org/linux-fscrypt/20200913083620.170627-1-ebiggers@kernel.org/ > which went into 5.10. The more recent patch to remove ext4_dir_open() isn't > related. > > It's a hard patch series to backport. Backporting it to 5.4 would be somewhat > feasible, while 4.19 would be very difficult as there have been a lot of other > fscrypt commits which would heavily conflict with cherry-picks. > > How interested are you in having this fixed? Did you encounter an actual > deadlock or just the lockdep report? Difficult to say. On one hand 'yes' I see lockups on my devices (4.19 kernel); I can't tell at the moment what's the root cause. So on the other hand 'no' I can't say that it's because of ext4_dir_open(). What I saw so far involved ext4, kswapd, khugepaged and lots of other things. [ 1598.655901] INFO: task khugepaged:66 blocked for more than 122 seconds. [ 1598.655914] Call Trace: [ 1598.655920] __schedule+0x506/0x1240 [ 1598.655924] ? kvm_zap_rmapp+0x52/0x69 [ 1598.655927] schedule+0x3f/0x78 [ 1598.655929] __rwsem_down_read_failed_common+0x186/0x201 [ 1598.655933] call_rwsem_down_read_failed+0x14/0x30 [ 1598.655936] down_read+0x2e/0x45 [ 1598.655939] rmap_walk_file+0x73/0x1ce [ 1598.655941] page_referenced+0x10d/0x154 [ 1598.655948] shrink_active_list+0x1d4/0x475 [..] [ 1598.655986] INFO: task kswapd0:79 blocked for more than 122 seconds. [ 1598.655993] Call Trace: [ 1598.655995] __schedule+0x506/0x1240 [ 1598.655998] schedule+0x3f/0x78 [ 1598.656000] __rwsem_down_read_failed_common+0x186/0x201 [ 1598.656003] call_rwsem_down_read_failed+0x14/0x30 [ 1598.656006] down_read+0x2e/0x45 [ 1598.656008] rmap_walk_file+0x73/0x1ce [ 1598.656010] page_referenced+0x10d/0x154 [ 1598.656015] shrink_active_list+0x1d4/0x475 [..] [ 1598.658233] __rwsem_down_read_failed_common+0x186/0x201 [ 1598.658235] call_rwsem_down_read_failed+0x14/0x30 [ 1598.658238] down_read+0x2e/0x45 [ 1598.658240] rmap_walk_file+0x73/0x1ce [ 1598.658242] page_referenced+0x10d/0x154 [ 1598.658247] shrink_active_list+0x1d4/0x475 [ 1598.658250] shrink_node+0x27e/0x661 [ 1598.658254] try_to_free_pages+0x425/0x7ec [ 1598.658258] __alloc_pages_nodemask+0x80b/0x1514 [ 1598.658279] __do_page_cache_readahead+0xd4/0x1a9 [ 1598.658282] filemap_fault+0x346/0x573 [ 1598.658287] ext4_filemap_fault+0x31/0x44 -ss