Re: [syzbot] INFO: task hung in jbd2_journal_commit_transaction (3)

From: Jan Kara <jack@suse.cz>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Theodore Ts'o <tytso@mit.edu>, Hillf Danton <hdanton@sina.com>,
	Matthew Wilcox <willy@infradead.org>,
	syzbot <syzbot+9c3fb12e9128b6e1d7eb@syzkaller.appspotmail.com>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	syzkaller-bugs@googlegroups.com,
	syzkaller <syzkaller@googlegroups.com>,
	Aleksandr Nogikh <nogikh@google.com>
Subject: Re: [syzbot] INFO: task hung in jbd2_journal_commit_transaction (3)
Date: Tue, 24 May 2022 12:59:10 +0200	[thread overview]
Message-ID: <20220524105910.ijkcppxzddrfrmop@quack3.lan> (raw)
In-Reply-To: <CACT4Y+ZHCawp__HvJAFPXp+z6XdiVEgwrh8dvDR+cDfQywr20w@mail.gmail.com>

On Mon 23-05-22 13:34:23, Dmitry Vyukov wrote:
> +Aleksandr added this feature recently.
> 
> Console output will contain strace output for reproducers (when the
> run under strace reproduced the same kernel crash as w/o strace).
> 
> Here is a recently reported bug:
> https://syzkaller.appspot.com/bug?id=53c9bd2ca0e16936e45ff1333a22b838d91da0a2
> 
> "log" link for the reproducer crash shows:
> https://syzkaller.appspot.com/text?tag=CrashLog&x=14f791aef00000
> ...
> 
> [   26.757008][ T3179] 8021q: adding VLAN 0 to HW filter on device bond0
> [   26.766878][ T3179] eql: remember to turn off Van-Jacobson
> compression on your slave devices
> Starting sshd: OK
> Warning: Permanently added '10.128.0.110' (ECDSA) to the list of known hosts.
> execve("./syz-executor1865045535", ["./syz-executor1865045535"],
> 0x7ffdc91edf40 /* 10 vars */) = 0
> brk(NULL)                               = 0x555557248000
> brk(0x555557248c40)                     = 0x555557248c40
> arch_prctl(ARCH_SET_FS, 0x555557248300) = 0
> uname({sysname="Linux", nodename="syzkaller", ...}) = 0
> readlink("/proc/self/exe", "/root/syz-executor1865045535", 4096) = 28
> brk(0x555557269c40)                     = 0x555557269c40
> brk(0x55555726a000)                     = 0x55555726a000
> mprotect(0x7f37f8ecc000, 16384, PROT_READ) = 0
> mmap(0x1ffff000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS,
> -1, 0) = 0x1ffff000
> mmap(0x20000000, 16777216, PROT_READ|PROT_WRITE|PROT_EXEC,
> MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x20000000
> mmap(0x21000000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS,
> -1, 0) = 0x21000000
> socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER) = 3
> syzkaller login: [   58.834018][ T3600] ------------[ cut here ]------------
> [   58.839772][ T3600] WARNING: CPU: 0 PID: 3600 at
> net/netfilter/nfnetlink.c:703 nfnetlink_unbind+0x357/0x3b0
> [   58.849856][ T3600] Modules linked in:
> ...
> 
> 
> The same is available in the report emails, e.g.:
> https://lore.kernel.org/all/000000000000ff239c05df391402@google.com/
> ...
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=14f791aef00000
> ...

Wow, cool! Thanks for adding that! This was often one of the first steps I
did when looking into what the problem could be so it saves me some manual
work :)

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR