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=-2.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 A3ECBC3F68F for ; Sat, 21 Dec 2019 14:02:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 75C2121D7D for ; Sat, 21 Dec 2019 14:02:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="Aq5/F4sI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726976AbfLUOC2 (ORCPT ); Sat, 21 Dec 2019 09:02:28 -0500 Received: from mail-pg1-f194.google.com ([209.85.215.194]:45761 "EHLO mail-pg1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726802AbfLUOC2 (ORCPT ); Sat, 21 Dec 2019 09:02:28 -0500 Received: by mail-pg1-f194.google.com with SMTP id b9so6427569pgk.12 for ; Sat, 21 Dec 2019 06:02:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=7Lc+T/FNxbn2ck1uy8M9pSQdxYkpPnlZqGKQGiC0A2o=; b=Aq5/F4sIrm5dfV542L953T1FmPHcqItoJmm2EIFZGpVQG33isOI5UNIr8NvYlciJeC gq2JHaLel1Y0yAeVNPLZjMAQp1i2b2I1rR2vEj2s2FRP3eOgrbIYWn8gA2SyUPMY0Jux w5P1bE/0lz0d6I39Kf6HbzwG+07RVDQ7YiKVBEoDrzUrr9+KVxA4fDjI2zIkjF1zbzZu 7JjotrKEoNx0w0aRjWjHGU1uoSXdoT7gT81XVUHOCJuoZaLtg3sdM9oNqBWtMQjKl58k e4QbswW2zTJKVJrMjyYm5K95L+z6v9I1sBWUQp6/0Sz5RlM+j47xaswFV2bJqMv/yp4V Twaw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=7Lc+T/FNxbn2ck1uy8M9pSQdxYkpPnlZqGKQGiC0A2o=; b=JNHsLLgI4+NsyEE2AXPSRR0VpRUT3xX5ASiXm1LlEwU4ns/iDvxrOBuGhTyKRIj1w+ hVJTJRgrxc/1oyi0Fktip/Z1jpRYJFBnVwNizwE7x9aYonfJeg8wWe1NcuQtF+6eVwcH 4g16FgUZznu63dHNjxZmMdPfd1ymm0tNZXMjriDjOGsrSWzteskBqQzqWWf5k7waebGs DHs8Pmhzo3XnYwwNuxgOVzG3MwD2+d09Nj34Kn9H2iVZkSPsSzPPNakp7/C+bNcLDYBT 74KniV4yL2OvriuSgg/Ol6anIxXuY//Myps5PS3+u7NfncmyOqLzXFx0wguvvKeHRnQ1 nTjw== X-Gm-Message-State: APjAAAWI9ItIVkatxGVAMJpRTYckiWEL1weWSAh02cEm7b7Fzi8dZPq4 pZB7mDNVGH5w4/GgjkPh3T5mVA== X-Google-Smtp-Source: APXvYqwNUe16DaQdazgidIHMcdaImKxGvQ4eoQK+A96GKZTFrbxfU7+5A9OnYW6DowHegnfgQpZ76g== X-Received: by 2002:a65:6842:: with SMTP id q2mr21438814pgt.345.1576936947397; Sat, 21 Dec 2019 06:02:27 -0800 (PST) Received: from [192.168.1.188] ([66.219.217.145]) by smtp.gmail.com with ESMTPSA id 65sm17954237pfu.140.2019.12.21.06.02.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 21 Dec 2019 06:02:26 -0800 (PST) Subject: Re: WARNING in percpu_ref_exit (2) To: Hillf Danton , syzbot Cc: io-uring@vger.kernel.org, viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com References: <20191221134330.7376-1-hdanton@sina.com> From: Jens Axboe Message-ID: <94c867f3-7310-573f-9fbd-088d4a75d6a3@kernel.dk> Date: Sat, 21 Dec 2019 07:02:25 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20191221134330.7376-1-hdanton@sina.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 12/21/19 6:43 AM, Hillf Danton wrote: > > On Sat, 21 Dec 2019 00:05:07 -0800 >> Hello, >> >> syzbot found the following crash on: >> >> HEAD commit: 7ddd09fc Add linux-next specific files for 20191220 >> git tree: linux-next >> console output: https://syzkaller.appspot.com/x/log.txt?x=12a18cc6e00000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=f183b01c3088afc6 >> dashboard link: https://syzkaller.appspot.com/bug?extid=8c4a14856e657b43487c >> compiler: gcc (GCC) 9.0.0 20181231 (experimental) >> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14b8f351e00000 >> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14b51925e00000 >> >> IMPORTANT: if you fix the bug, please add the following tag to the commit: >> Reported-by: syzbot+8c4a14856e657b43487c@syzkaller.appspotmail.com >> >> ------------[ cut here ]------------ >> WARNING: CPU: 1 PID: 11482 at lib/percpu-refcount.c:111 >> percpu_ref_exit+0xab/0xd0 lib/percpu-refcount.c:111 >> Kernel panic - not syncing: panic_on_warn set ... >> CPU: 1 PID: 11482 Comm: syz-executor051 Not tainted >> 5.5.0-rc2-next-20191220-syzkaller #0 >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS >> Google 01/01/2011 >> Call Trace: >> __dump_stack lib/dump_stack.c:77 [inline] >> dump_stack+0x197/0x210 lib/dump_stack.c:118 >> panic+0x2e3/0x75c kernel/panic.c:221 >> __warn.cold+0x2f/0x3e kernel/panic.c:582 >> report_bug+0x289/0x300 lib/bug.c:195 >> fixup_bug arch/x86/kernel/traps.c:174 [inline] >> fixup_bug arch/x86/kernel/traps.c:169 [inline] >> do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:267 >> do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:286 >> invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027 >> RIP: 0010:percpu_ref_exit+0xab/0xd0 lib/percpu-refcount.c:111 >> Code: 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 75 1d 48 c7 43 08 03 00 >> 00 00 e8 01 41 e5 fd 5b 41 5c 41 5d 5d c3 e8 f5 40 e5 fd <0f> 0b eb bf 4c >> 89 ef e8 29 2c 23 fe eb d9 e8 82 2b 23 fe eb a7 4c >> RSP: 0018:ffffc9000cb17968 EFLAGS: 00010293 >> RAX: ffff8880a3390640 RBX: ffff8880a83a8010 RCX: ffffffff83901432 >> RDX: 0000000000000000 RSI: ffffffff8390149b RDI: ffff8880a83a8028 >> RBP: ffffc9000cb17980 R08: ffff8880a3390640 R09: 0000000000000000 >> R10: 0000000000000000 R11: 0000000000000000 R12: 0000607f51435750 >> R13: ffff8880a83a8018 R14: ffff888097b95000 R15: ffff888097b95228 >> io_sqe_files_unregister+0x7d/0x2f0 fs/io_uring.c:4623 >> io_ring_ctx_free fs/io_uring.c:5575 [inline] >> io_ring_ctx_wait_and_kill+0x430/0x9a0 fs/io_uring.c:5644 >> io_uring_release+0x42/0x50 fs/io_uring.c:5652 >> __fput+0x2ff/0x890 fs/file_table.c:280 >> ____fput+0x16/0x20 fs/file_table.c:313 >> task_work_run+0x145/0x1c0 kernel/task_work.c:113 >> exit_task_work include/linux/task_work.h:22 [inline] >> do_exit+0x909/0x2f20 kernel/exit.c:797 >> do_group_exit+0x135/0x360 kernel/exit.c:895 >> get_signal+0x47c/0x24f0 kernel/signal.c:2734 >> do_signal+0x87/0x1700 arch/x86/kernel/signal.c:815 >> exit_to_usermode_loop+0x286/0x380 arch/x86/entry/common.c:160 >> prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] >> syscall_return_slowpath arch/x86/entry/common.c:278 [inline] >> do_syscall_64+0x676/0x790 arch/x86/entry/common.c:304 >> entry_SYSCALL_64_after_hwframe+0x49/0xbe > > Flush work before killing. > > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -4618,10 +4618,10 @@ static int io_sqe_files_unregister(struc > if (!data) > return -ENXIO; > > + flush_work(&data->ref_work); > percpu_ref_kill_and_confirm(&data->refs, io_file_ref_kill); > wait_for_completion(&data->done); > percpu_ref_exit(&data->refs); > - flush_work(&data->ref_work); > > __io_sqe_files_unregister(ctx); > nr_tables = DIV_ROUND_UP(ctx->nr_user_files, IORING_MAX_FILES_TABLE); Oh indeed, good catch! Thanks, I'll fold this in. -- Jens Axboe