Re: BUG: MAX_STACK_TRACE_ENTRIES too low!

From: Christoph Hellwig <hch@infradead.org>
To: syzbot <syzbot+78923eea7cf44364f4fb@syzkaller.appspotmail.com>
Cc: darrick.wong@oracle.com, linux-kernel@vger.kernel.org,
	linux-xfs@vger.kernel.org, syzkaller-bugs@googlegroups.com,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will.deacon@arm.com>
Subject: Re: BUG: MAX_STACK_TRACE_ENTRIES too low!
Date: Fri, 8 Mar 2019 00:11:07 -0800	[thread overview]
Message-ID: <20190308081107.GD22834@infradead.org> (raw)
In-Reply-To: <000000000000299b190583172880@google.com>

Probably more a lockdep than XFS thing..

On Fri, Mar 01, 2019 at 11:06:04PM -0800, syzbot wrote:
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    c63e9e91a254 Add linux-next specific files for 20190301
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=16a559b2c00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=f5875f9dc6e009b2
> dashboard link: https://syzkaller.appspot.com/bug?extid=78923eea7cf44364f4fb
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> 
> Unfortunately, I don't have any reproducer for this crash yet.
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+78923eea7cf44364f4fb@syzkaller.appspotmail.com
> 
> BUG: MAX_STACK_TRACE_ENTRIES too low!
> turning off the locking correctness validator.
> CPU: 0 PID: 19385 Comm: syz-executor.0 Not tainted 5.0.0-rc8-next-20190301
> #1
> 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+0x172/0x1f0 lib/dump_stack.c:113
>  save_trace kernel/locking/lockdep.c:467 [inline]
>  save_trace.cold+0x14/0x19 kernel/locking/lockdep.c:437
>  mark_lock+0x2fb/0x1380 kernel/locking/lockdep.c:3401
>  __lock_acquire+0x548/0x3fb0 kernel/locking/lockdep.c:3648
>  lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4202
>  flush_workqueue+0x126/0x14c0 kernel/workqueue.c:2774
>  drain_workqueue+0x1b4/0x470 kernel/workqueue.c:2939
>  destroy_workqueue+0x21/0x700 kernel/workqueue.c:4315
>  xfs_destroy_mount_workqueues+0x11d/0x1c0 fs/xfs/xfs_super.c:906
>  xfs_fs_fill_super+0x8e9/0x1670 fs/xfs/xfs_super.c:1786
>  mount_bdev+0x307/0x3c0 fs/super.c:1346
>  xfs_fs_mount+0x35/0x40 fs/xfs/xfs_super.c:1834
>  legacy_get_tree+0xf2/0x200 fs/fs_context.c:584
>  vfs_get_tree+0x123/0x450 fs/super.c:1481
>  do_new_mount fs/namespace.c:2622 [inline]
>  do_mount+0x1436/0x2c40 fs/namespace.c:2942
>  ksys_mount+0xdb/0x150 fs/namespace.c:3151
>  __do_sys_mount fs/namespace.c:3165 [inline]
>  __se_sys_mount fs/namespace.c:3162 [inline]
>  __x64_sys_mount+0xbe/0x150 fs/namespace.c:3162
>  do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x45a89a
> Code: b8 a6 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 2d 8e fb ff c3 66 2e 0f
> 1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff
> 0f 83 0a 8e fb ff c3 66 0f 1f 84 00 00 00 00 00
> RSP: 002b:00007f6d038b0a88 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5
> RAX: ffffffffffffffda RBX: 00007f6d038b0b30 RCX: 000000000045a89a
> RDX: 00007f6d038b0ad0 RSI: 0000000020000140 RDI: 00007f6d038b0af0
> RBP: 0000000020000140 R08: 00007f6d038b0b30 R09: 00007f6d038b0ad0
> R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000003
> R13: 0000000000000000 R14: 00000000004dbde0 R15: 00000000ffffffff
> 
> 
> ---
> This bug is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
> 
> syzbot will keep track of this bug report. See:
> https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
> syzbot.
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