====================================================== WARNING: possible circular locking dependency detected 4.15.0-rc8+ #1 Not tainted ------------------------------------------------------ syzkaller527375/3669 is trying to acquire lock: (event_mutex){+.+.}, at: [<00000000f305855f>] perf_trace_destroy+0x28/0x100 kernel/trace/trace_event_perf.c:234 but task is already holding lock: (&event->child_mutex){+.+.}, at: [<000000004142c631>] perf_event_release_kernel+0x2ea/0xc10 kernel/events/core.c:4260 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (&event->child_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 perf_event_for_each_child+0x8a/0x150 kernel/events/core.c:4557 perf_event_for_each kernel/events/core.c:4574 [inline] _perf_ioctl kernel/events/core.c:4734 [inline] perf_ioctl+0x46b/0x1430 kernel/events/core.c:4748 vfs_ioctl fs/ioctl.c:46 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 entry_SYSCALL_64_fastpath+0x29/0xa0 -> #4 (&cpuctx_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 perf_event_init_cpu+0xb6/0x160 kernel/events/core.c:11076 perf_event_init+0x4e9/0x549 kernel/events/core.c:11123 start_kernel+0x4cc/0x819 init/main.c:627 x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:378 x86_64_start_kernel+0x77/0x7a arch/x86/kernel/head64.c:359 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:237 -> #3 (pmus_lock){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 perf_event_init_cpu+0x2f/0x160 kernel/events/core.c:11070 cpuhp_invoke_callback+0x2ea/0x1d20 kernel/cpu.c:182 cpuhp_up_callbacks kernel/cpu.c:477 [inline] _cpu_up+0x216/0x510 kernel/cpu.c:1036 do_cpu_up+0x73/0xa0 kernel/cpu.c:1066 cpu_up+0x18/0x20 kernel/cpu.c:1074 smp_init+0x13a/0x152 kernel/smp.c:578 kernel_init_freeable+0x2fe/0x521 init/main.c:1067 kernel_init+0x13/0x180 init/main.c:999 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:541 -> #2 (cpu_hotplug_lock.rw_sem){++++}: percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36 [inline] percpu_down_read include/linux/percpu-rwsem.h:59 [inline] cpus_read_lock+0x42/0x90 kernel/cpu.c:293 static_key_slow_inc+0x9d/0x3c0 kernel/jump_label.c:123 tracepoint_add_func kernel/tracepoint.c:223 [inline] tracepoint_probe_register_prio+0x80d/0x9a0 kernel/tracepoint.c:283 tracepoint_probe_register+0x2a/0x40 kernel/tracepoint.c:304 trace_event_reg+0x167/0x320 kernel/trace/trace_events.c:305 perf_trace_event_reg kernel/trace/trace_event_perf.c:122 [inline] perf_trace_event_init kernel/trace/trace_event_perf.c:197 [inline] perf_trace_init+0x4ef/0xab0 kernel/trace/trace_event_perf.c:221 perf_tp_event_init+0x7d/0xf0 kernel/events/core.c:7959 perf_try_init_event+0xc9/0x1f0 kernel/events/core.c:9192 perf_init_event kernel/events/core.c:9230 [inline] perf_event_alloc+0x1cc6/0x2b00 kernel/events/core.c:9494 SYSC_perf_event_open+0x84e/0x2e00 kernel/events/core.c:9949 SyS_perf_event_open+0x39/0x50 kernel/events/core.c:9835 entry_SYSCALL_64_fastpath+0x29/0xa0 -> #1 (tracepoints_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 tracepoint_probe_register_prio+0xa0/0x9a0 kernel/tracepoint.c:279 tracepoint_probe_register+0x2a/0x40 kernel/tracepoint.c:304 trace_event_reg+0x167/0x320 kernel/trace/trace_events.c:305 perf_trace_event_reg kernel/trace/trace_event_perf.c:122 [inline] perf_trace_event_init kernel/trace/trace_event_perf.c:197 [inline] perf_trace_init+0x4ef/0xab0 kernel/trace/trace_event_perf.c:221 perf_tp_event_init+0x7d/0xf0 kernel/events/core.c:7959 perf_try_init_event+0xc9/0x1f0 kernel/events/core.c:9192 perf_init_event kernel/events/core.c:9230 [inline] perf_event_alloc+0x1cc6/0x2b00 kernel/events/core.c:9494 SYSC_perf_event_open+0x84e/0x2e00 kernel/events/core.c:9949 SyS_perf_event_open+0x39/0x50 kernel/events/core.c:9835 entry_SYSCALL_64_fastpath+0x29/0xa0 -> #0 (event_mutex){+.+.}: lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3914 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 perf_trace_destroy+0x28/0x100 kernel/trace/trace_event_perf.c:234 tp_perf_event_destroy+0x15/0x20 kernel/events/core.c:7943 _free_event+0x3bd/0x10f0 kernel/events/core.c:4104 free_event+0x84/0x150 kernel/events/core.c:4128 perf_event_release_kernel+0x54e/0xc10 kernel/events/core.c:4272 perf_release+0x37/0x50 kernel/events/core.c:4298 __fput+0x327/0x7e0 fs/file_table.c:210 ____fput+0x15/0x20 fs/file_table.c:244 task_work_run+0x199/0x270 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x9bb/0x1ad0 kernel/exit.c:865 do_group_exit+0x149/0x400 kernel/exit.c:968 get_signal+0x73f/0x16c0 kernel/signal.c:2335 do_signal+0x90/0x1eb0 arch/x86/kernel/signal.c:809 exit_to_usermode_loop+0x214/0x310 arch/x86/entry/common.c:158 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] syscall_return_slowpath arch/x86/entry/common.c:264 [inline] do_syscall_64+0x6dc/0x920 arch/x86/entry/common.c:290 return_from_SYSCALL_64+0x0/0x75 other info that might help us debug this: Chain exists of: event_mutex --> &cpuctx_mutex --> &event->child_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&event->child_mutex); lock(&cpuctx_mutex); lock(&event->child_mutex); lock(event_mutex); *** DEADLOCK *** 2 locks held by syzkaller527375/3669: #0: (&ctx->mutex){+.+.}, at: [<00000000b54e8121>] perf_event_release_kernel+0x2dc/0xc10 kernel/events/core.c:4259 #1: (&event->child_mutex){+.+.}, at: [<000000004142c631>] perf_event_release_kernel+0x2ea/0xc10 kernel/events/core.c:4260 stack backtrace: CPU: 1 PID: 3669 Comm: syzkaller527375 Not tainted 4.15.0-rc8+ #1 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+0x194/0x257 lib/dump_stack.c:53 print_circular_bug.isra.37+0x2cd/0x2dc kernel/locking/lockdep.c:1218 check_prev_add kernel/locking/lockdep.c:1858 [inline] check_prevs_add kernel/locking/lockdep.c:1971 [inline] validate_chain kernel/locking/lockdep.c:2412 [inline] __lock_acquire+0x30a8/0x3e00 kernel/locking/lockdep.c:3426 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3914 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 perf_trace_destroy+0x28/0x100 kernel/trace/trace_event_perf.c:234 tp_perf_event_destroy+0x15/0x20 kernel/events/core.c:7943 _free_event+0x3bd/0x10f0 kernel/events/core.c:4104 free_event+0x84/0x150 kernel/events/core.c:4128 perf_event_release_kernel+0x54e/0xc10 kernel/events/core.c:4272 perf_release+0x37/0x50 kernel/events/core.c:4298 __fput+0x327/0x7e0 fs/file_table.c:210 ____fput+0x15/0x20 fs/file_table.c:244 task_work_run+0x199/0x270 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x9bb/0x1ad0 kernel/exit.c:865 do_group_exit+0x149/0x400 kernel/exit.c:968 get_signal+0x73f/0x16c0 kernel/signal.c:2335 do_signal+0x90/0x1eb0 arch/x86/kernel/signal.c:809 exit_to_usermode_loop+0x214/0x310 arch/x86/entry/common.c:158 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] syscall_return_slowpath arch/x86/entry/common.c:264 [inline] do_syscall_64+0x6dc/0x920 arch/x86/entry/common.c:290 entry_SYSCALL64_slow_path+0x25/0x25 RIP: 0033:0x445df9 RSP: 002b:00007f07b34c9db8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00000000006dbc3c RCX: 0000000000445df9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000006dbc3c RBP: 00000000006dbc38 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fffd43fdbef R14: 00007f07b34ca9c0 R15: 0000000000000005