WARNING in tracepoint_probe_unregister (2)

[syzbot]

Hello,

syzbot hit the following crash on bpf-next commit
6d8cb045cde681e64a5ed80a2ab70be831a7f9b0 (Fri Mar 9 07:46:33 2018 +0000)
bpf: comment why dots in filenames under BPF virtual FS are not allowed

So far this crash happened 2 times on bpf-next.
Unfortunately, I don't have any reproducer for this crash yet.
Raw console output is attached.
compiler: gcc (GCC) 7.1.1 20170620
.config is attached.

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RAX: 0000000000000000 RBX: 00007f399ae5c6d4 RCX: 0000000000453e69
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000013
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000014
R13: 0000000000000052 R14: 00000000006f0850 R15: 0000000000000000
WARNING: CPU: 1 PID: 23319 at kernel/tracepoint.c:242
tracepoint_remove_func kernel/tracepoint.c:242 [inline]
WARNING: CPU: 1 PID: 23319 at kernel/tracepoint.c:242
tracepoint_probe_unregister+0x6b3/0x870 kernel/tracepoint.c:323
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 23319 Comm: syz-executor6 Not tainted 4.16.0-rc4+ #28
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x194/0x24d lib/dump_stack.c:53
panic+0x1e4/0x41c kernel/panic.c:183
__warn+0x1dc/0x200 kernel/panic.c:547
report_bug+0x211/0x2d0 lib/bug.c:184
fixup_bug.part.11+0x37/0x80 arch/x86/kernel/traps.c:178
fixup_bug arch/x86/kernel/traps.c:247 [inline]
do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:296
do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:986
RIP: 0010:tracepoint_remove_func kernel/tracepoint.c:242 [inline]
RIP: 0010:tracepoint_probe_unregister+0x6b3/0x870 kernel/tracepoint.c:323
RSP: 0018:ffff8801c56a74d0 EFLAGS: 00010246
RAX: 0000000000010000 RBX: 00000000fffffff4 RCX: ffffffff81735193
RDX: 0000000000010000 RSI: ffffc900057fa000 RDI: 0000000000000286
RBP: ffff8801c56a75e8 R08: 1ffff10038ad4ded R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c1132dc0
R13: 0000000000000000 R14: ffff8801c1132d90 R15: ffff8801c56a75c0
trace_event_reg+0xed/0x320 kernel/trace/trace_events.c:309
perf_trace_event_unreg.isra.2+0xad/0x1f0
kernel/trace/trace_event_perf.c:155
perf_trace_destroy+0xbc/0x100 kernel/trace/trace_event_perf.c:236
tp_perf_event_destroy+0x15/0x20 kernel/events/core.c:7963
_free_event+0x3bd/0x10f0 kernel/events/core.c:4108
put_event+0x24/0x30 kernel/events/core.c:4191
perf_event_release_kernel+0x6e8/0xfc0 kernel/events/core.c:4297
perf_release+0x37/0x50 kernel/events/core.c:4307
__fput+0x327/0x7e0 fs/file_table.c:209
____fput+0x15/0x20 fs/file_table.c:243
task_work_run+0x199/0x270 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:191 [inline]
exit_to_usermode_loop+0x275/0x2f0 arch/x86/entry/common.c:166
prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
do_syscall_64+0x6ec/0x940 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x453e69
RSP: 002b:00007f399ae5bc68 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007f399ae5c6d4 RCX: 0000000000453e69
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000013
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000014
R13: 0000000000000052 R14: 00000000006f0850 R15: 0000000000000000
Dumping ftrace buffer:
(ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


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[Mathieu Desnoyers]

----- On Mar 13, 2018, at 3:32 AM, syzbot syzbot+4e9ae7...@syzkaller.appspotmail.com wrote:

> Hello,
>
> syzbot hit the following crash on bpf-next commit
> 6d8cb045cde681e64a5ed80a2ab70be831a7f9b0 (Fri Mar 9 07:46:33 2018 +0000)
> bpf: comment why dots in filenames under BPF virtual FS are not allowed

Here is the splat on unregister. I suspect this is caused by trying to
unregister a tracepoint which is already unregistered (or not yet
registered).

Thanks,

Mathieu

--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com

[Mathieu Desnoyers]

Also attachments for unregister splat.

----- On Mar 13, 2018, at 3:32 AM, syzbot syzbot+4e9ae7...@syzkaller.appspotmail.com wrote: