Message-ID: <000000000000e563d7056a35bbb3@google.com>
Date:   Thu, 19 Apr 2018 09:05:01 -0700
From:   syzbot <syzbot+9873874c735f2892e7e9@...kaller.appspotmail.com>
To:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com, viro@...iv.linux.org.uk
Subject: general protection fault in wb_workfn

Hello,

syzbot hit the following crash on upstream commit
3eb2ce825ea1ad89d20f7a3b5780df850e4be274 (Sun Mar 25 22:44:30 2018 +0000)
Linux 4.16-rc7
syzbot dashboard link:  
https://syzkaller.appspot.com/bug?extid=9873874c735f2892e7e9

So far this crash happened 29 times on upstream.
Unfortunately, I don't have any reproducer for this crash yet.
Raw console output:  
https://syzkaller.appspot.com/x/log.txt?id=6617474409693184
Kernel config:  
https://syzkaller.appspot.com/x/.config?id=-8440362230543204781
compiler: gcc (GCC) 7.1.1 20170620

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+9873874c735f2892e7e9@...kaller.appspotmail.com
It will help syzbot understand when the bug is fixed. See footer for  
details.
If you forward the report, please keep this part and the footer.

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
    (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 28 Comm: kworker/u4:2 Not tainted 4.16.0-rc7+ #368
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: writeback wb_workfn
RIP: 0010:dev_name include/linux/device.h:981 [inline]
RIP: 0010:wb_workfn+0x1a2/0x16b0 fs/fs-writeback.c:1936
RSP: 0018:ffff8801d951f038 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff81bf6ea5
RDX: 000000000000000a RSI: ffffffff87b44840 RDI: 0000000000000050
RBP: ffff8801d951f558 R08: 1ffff1003b2a3def R09: 0000000000000004
R10: ffff8801d951f438 R11: 0000000000000004 R12: 0000000000000100
R13: ffff8801baee0dc0 R14: ffff8801d951f530 R15: ffff8801baee10d8
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000047ff80 CR3: 0000000007a22006 CR4: 00000000001626f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  process_one_work+0xc47/0x1bb0 kernel/workqueue.c:2113
  process_scheduled_works kernel/workqueue.c:2173 [inline]
  worker_thread+0xa4b/0x1990 kernel/workqueue.c:2252
  kthread+0x33c/0x400 kernel/kthread.c:238
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:406
Code: fa 48 c1 ea 03 80 3c 02 00 0f 85 d9 14 00 00 48 8b 9b d0 05 00 00 48  
b8 00 00 00 00 00 fc ff df 48 8d 7b 50 48 89 fa 48 c1 ea 03 <80> 3c 02 00  
0f 85 a9 14 00 00 4c 8b 63 50 4d 85 e4 0f 84 49 0e
RIP: dev_name include/linux/device.h:981 [inline] RSP: ffff8801d951f038
RIP: wb_workfn+0x1a2/0x16b0 fs/fs-writeback.c:1936 RSP: ffff8801d951f038
---[ end trace 303e9927650f10c6 ]---
Kernel panic - not syncing: Fatal exception
Dumping ftrace buffer:
    (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This bug is generated by a dumb bot. It may contain errors.
See https://goo.gl/tpsmEJ for details.
Direct all questions to syzkaller@...glegroups.com.

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