Re: WARNING in tracepoint_probe_unregister

[Dmitry Vyukov]

On Tue, Nov 7, 2017 at 7:08 PM, Jens Axboe <axboe@xxxxxxxxx> wrote:
> On 11/07/2017 11:06 AM, Dmitry Vyukov wrote:
>> On Sun, Nov 5, 2017 at 4:47 PM, Jens Axboe <axboe@xxxxxxxxx> wrote:
>>> On 11/05/2017 01:09 AM, Dmitry Vyukov wrote:
>>>> On Sun, Nov 5, 2017 at 11:05 AM, syzbot
>>>> <bot+f00b2fc1cf284703bf4107c0ea565aafd9b536d0@xxxxxxxxxxxxxxxxxxxxxxxxx>
>>>> wrote:
>>>>> Hello,
>>>>>
>>>>> syzkaller hit the following crash on
>>>>> 36ef71cae353f88fd6e095e2aaa3e5953af1685d
>>>>> git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
>>>>> compiler: gcc (GCC) 7.1.1 20170620
>>>>> .config is attached
>>>>> Raw console output is attached.
>>>>> C reproducer is attached
>>>>> syzkaller reproducer is attached. See https://goo.gl/kgGztJ
>>>>> for information about syzkaller reproducers
>>>>>
>>>>>
>>>>> WARNING: CPU: 1 PID: 2992 at kernel/tracepoint.c:243 tracepoint_remove_func
>>>>> kernel/tracepoint.c:243 [inline]
>>>>> WARNING: CPU: 1 PID: 2992 at kernel/tracepoint.c:243
>>>>> tracepoint_probe_unregister+0x6b3/0x870 kernel/tracepoint.c:324
>>>>> Kernel panic - not syncing: panic_on_warn set ...
>>>>>
>>>>> CPU: 1 PID: 2992 Comm: syzkaller812809 Not tainted 4.14.0-rc5-next-20171018+
>>>>> #8
>>>>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
>>>>> Call Trace:
>>>>>  __dump_stack lib/dump_stack.c:16 [inline]
>>>>>  dump_stack+0x194/0x257 lib/dump_stack.c:52
>>>>>  panic+0x1e4/0x41c kernel/panic.c:183
>>>>>  __warn+0x1c4/0x1e0 kernel/panic.c:546
>>>>>  report_bug+0x211/0x2d0 lib/bug.c:183
>>>>>  fixup_bug+0x40/0x90 arch/x86/kernel/traps.c:177
>>>>>  do_trap_no_signal arch/x86/kernel/traps.c:211 [inline]
>>>>>  do_trap+0x260/0x390 arch/x86/kernel/traps.c:260
>>>>>  do_error_trap+0x120/0x390 arch/x86/kernel/traps.c:297
>>>>>  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:310
>>>>>  invalid_op+0x18/0x20 arch/x86/entry/entry_64.S:905
>>>>> RIP: 0010:tracepoint_remove_func kernel/tracepoint.c:243 [inline]
>>>>> RIP: 0010:tracepoint_probe_unregister+0x6b3/0x870 kernel/tracepoint.c:324
>>>>> RSP: 0018:ffff8800397df890 EFLAGS: 00010293
>>>>> RAX: ffff88003982e8c0 RBX: 00000000fffffffe RCX: ffffffff81710233
>>>>> RDX: 0000000000000000 RSI: ffffffff85b679c0 RDI: 0000000000000282
>>>>> RBP: ffff8800397df9a8 R08: 0000000000000001 R09: 1ffff100072fbe6e
>>>>> R10: ffff8800397df880 R11: 0000000000000001 R12: ffffffff8175b5e0
>>>>> R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8800397df980
>>>>>  unregister_trace_block_rq_remap include/trace/events/block.h:602 [inline]
>>>>>  blk_unregister_tracepoints+0x1e/0x160 kernel/trace/blktrace.c:1079
>>>>>  blk_trace_cleanup+0x28/0x30 kernel/trace/blktrace.c:336
>>>>>  blk_trace_remove+0x55/0x80 kernel/trace/blktrace.c:348
>>>>>  sg_ioctl+0x5eb/0x2d90 drivers/scsi/sg.c:1098
>>>>>  vfs_ioctl fs/ioctl.c:45 [inline]
>>>>>  do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:685
>>>>>  SYSC_ioctl fs/ioctl.c:700 [inline]
>>>>>  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
>>>>>  entry_SYSCALL_64_fastpath+0x1f/0xbe
>>>>> RIP: 0033:0x4396a9
>>>>> RSP: 002b:00007ffd4d3facb8 EFLAGS: 00000206 ORIG_RAX: 0000000000000010
>>>>> RAX: ffffffffffffffda RBX: 00000000006ccac0 RCX: 00000000004396a9
>>>>> RDX: 000000002002d000 RSI: 4000000000001276 RDI: 0000000000000004
>>>>> RBP: 0000000000000082 R08: 00000000000000fe R09: 0000000000000000
>>>>> R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000038
>>>>> R13: ffffffffffffffff R14: 0000000000401eb0 R15: 0000000000000000
>>>>> Dumping ftrace buffer:
>>>>>    (ftrace buffer empty)
>>>>> Kernel Offset: disabled
>>>>> Rebooting in 86400 seconds..
>>>>
>>>>
>>>> Jens, this has the same root cause as "WARNING in
>>>> tracepoint_probe_register_prio":
>>>> https://groups.google.com/forum/#!msg/syzkaller-bugs/9IolqTA_NUk/LgLFZ6hQAQAJ
>>>> right?
>>>
>>> Yep, it is - can/did you check the patch I sent out yesterday for this?
>>> Here it is again.
>>
>> I re-run the attached reproducer and it does not trigger the warning
>> with the patch:
>>
>> Tested-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
>
> Great, thanks for testing!


Please also follow this part on the patch reaches any of the trees:

> syzbot will keep track of this bug report.
> Once a fix for this bug is committed, please reply to this email with:
> #syz fix: exact-commit-title
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This will greatly help keeping the whole process running and report
new bugs in future.

Thanks