======================================================
WARNING: possible circular locking dependency detected
4.14.140+ #39 Not tainted
------------------------------------------------------
syz-executor.2/1870 is trying to acquire lock:
 (&cpuctx_mutex/1){+.+.}, at: [<00000000171d310b>] mutex_lock_double kernel/events/core.c:9909 [inline]
 (&cpuctx_mutex/1){+.+.}, at: [<00000000171d310b>] __perf_event_ctx_lock_double kernel/events/core.c:9968 [inline]
 (&cpuctx_mutex/1){+.+.}, at: [<00000000171d310b>] SYSC_perf_event_open kernel/events/core.c:10233 [inline]
 (&cpuctx_mutex/1){+.+.}, at: [<00000000171d310b>] SyS_perf_event_open+0x12cf/0x2560 kernel/events/core.c:9988

but task is already holding lock:
 (&cpuctx_mutex){+.+.}, at: [<0000000067a1734e>] mutex_lock_double kernel/events/core.c:9908 [inline]
 (&cpuctx_mutex){+.+.}, at: [<0000000067a1734e>] __perf_event_ctx_lock_double kernel/events/core.c:9968 [inline]
 (&cpuctx_mutex){+.+.}, at: [<0000000067a1734e>] SYSC_perf_event_open kernel/events/core.c:10233 [inline]
 (&cpuctx_mutex){+.+.}, at: [<0000000067a1734e>] SyS_perf_event_open+0x12c2/0x2560 kernel/events/core.c:9988

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&cpuctx_mutex){+.+.}:
       __mutex_lock_common kernel/locking/mutex.c:756 [inline]
       __mutex_lock+0xf7/0x13e0 kernel/locking/mutex.c:893
       perf_event_init_cpu+0xa8/0x150 kernel/events/core.c:11231
       perf_event_init+0x289/0x2c5 kernel/events/core.c:11278
       start_kernel+0x43d/0x74a init/main.c:621
       secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:240

-> #1 (pmus_lock){+.+.}:
       __mutex_lock_common kernel/locking/mutex.c:756 [inline]
       __mutex_lock+0xf7/0x13e0 kernel/locking/mutex.c:893
       swevent_hlist_get kernel/events/core.c:7896 [inline]
       perf_swevent_init+0x123/0x4f0 kernel/events/core.c:7956
       perf_try_init_event+0xe5/0x200 kernel/events/core.c:9347
       perf_init_event kernel/events/core.c:9385 [inline]
       perf_event_alloc.part.0+0xd13/0x1ff0 kernel/events/core.c:9645
       perf_event_alloc kernel/events/core.c:9998 [inline]
       SYSC_perf_event_open kernel/events/core.c:10105 [inline]
       SyS_perf_event_open+0x6eb/0x2560 kernel/events/core.c:9988
       do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292
       entry_SYSCALL_64_after_hwframe+0x42/0xb7

-> #0 (&cpuctx_mutex/1){+.+.}:
       lock_acquire+0x12b/0x360 kernel/locking/lockdep.c:3991
       __mutex_lock_common kernel/locking/mutex.c:756 [inline]
       __mutex_lock+0xf7/0x13e0 kernel/locking/mutex.c:893
       mutex_lock_double kernel/events/core.c:9909 [inline]
       __perf_event_ctx_lock_double kernel/events/core.c:9968 [inline]
       SYSC_perf_event_open kernel/events/core.c:10233 [inline]
       SyS_perf_event_open+0x12cf/0x2560 kernel/events/core.c:9988
       do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292
       entry_SYSCALL_64_after_hwframe+0x42/0xb7

other info that might help us debug this:

Chain exists of:
  &cpuctx_mutex/1 --> pmus_lock --> &cpuctx_mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&cpuctx_mutex);
                               lock(pmus_lock);
                               lock(&cpuctx_mutex);
  lock(&cpuctx_mutex/1);

 *** DEADLOCK ***

1 lock held by syz-executor.2/1870:
 #0:  (&cpuctx_mutex){+.+.}, at: [<0000000067a1734e>] mutex_lock_double kernel/events/core.c:9908 [inline]
 #0:  (&cpuctx_mutex){+.+.}, at: [<0000000067a1734e>] __perf_event_ctx_lock_double kernel/events/core.c:9968 [inline]
 #0:  (&cpuctx_mutex){+.+.}, at: [<0000000067a1734e>] SYSC_perf_event_open kernel/events/core.c:10233 [inline]
 #0:  (&cpuctx_mutex){+.+.}, at: [<0000000067a1734e>] SyS_perf_event_open+0x12c2/0x2560 kernel/events/core.c:9988

stack backtrace:
CPU: 0 PID: 1870 Comm: syz-executor.2 Not tainted 4.14.140+ #39
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xca/0x134 lib/dump_stack.c:53
 print_circular_bug.isra.0.cold+0x2dc/0x425 kernel/locking/lockdep.c:1258
 check_prev_add kernel/locking/lockdep.c:1901 [inline]
 check_prevs_add kernel/locking/lockdep.c:2018 [inline]
 validate_chain kernel/locking/lockdep.c:2460 [inline]
 __lock_acquire+0x2f5f/0x4320 kernel/locking/lockdep.c:3487
 lock_acquire+0x12b/0x360 kernel/locking/lockdep.c:3991
 __mutex_lock_common kernel/locking/mutex.c:756 [inline]
 __mutex_lock+0xf7/0x13e0 kernel/locking/mutex.c:893
 mutex_lock_double kernel/events/core.c:9909 [inline]
 __perf_event_ctx_lock_double kernel/events/core.c:9968 [inline]
 SYSC_perf_event_open kernel/events/core.c:10233 [inline]
 SyS_perf_event_open+0x12cf/0x2560 kernel/events/core.c:9988
 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x459879
RSP: 002b:00007fc55fe68c78 EFLAGS: 00000246 ORIG_RAX: 000000000000012a
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459879
RDX: 0000000000000000 RSI: ffffffffffffffff RDI: 0000000020000200
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000246 R12: 00007fc55fe696d4
R13: 00000000004c66e4 R14: 00000000004db758 R15: 00000000ffffffff
ip6_tunnel: ip6tnl1 xmit: Local address not yet configured!