====================================================== WARNING: possible circular locking dependency detected 4.14.180-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.1/23031 is trying to acquire lock: (&event->child_mutex){+.+.}, at: [] perf_read_group kernel/events/core.c:4536 [inline] (&event->child_mutex){+.+.}, at: [] __perf_read kernel/events/core.c:4618 [inline] (&event->child_mutex){+.+.}, at: [] perf_read+0x2a1/0x7c0 kernel/events/core.c:4633 but task is already holding lock: (&cpuctx_mutex){+.+.}, at: [] perf_event_ctx_lock_nested+0x14d/0x2c0 kernel/events/core.c:1235 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (&cpuctx_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893 perf_event_init_cpu+0xb7/0x170 kernel/events/core.c:11244 perf_event_init+0x2cc/0x308 kernel/events/core.c:11291 start_kernel+0x3b1/0x676 init/main.c:620 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:240 -> #4 (pmus_lock){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893 perf_event_init_cpu+0x2c/0x170 kernel/events/core.c:11238 cpuhp_invoke_callback+0x1e6/0x1ad0 kernel/cpu.c:184 cpuhp_up_callbacks kernel/cpu.c:572 [inline] _cpu_up+0x21a/0x520 kernel/cpu.c:1140 do_cpu_up kernel/cpu.c:1175 [inline] do_cpu_up+0x9a/0x160 kernel/cpu.c:1147 smp_init+0x149/0x15e kernel/smp.c:578 kernel_init_freeable+0x305/0x526 init/main.c:1066 kernel_init+0xd/0x15b init/main.c:998 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 -> #3 (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+0x39/0xc0 kernel/cpu.c:295 static_key_slow_inc+0xe/0x20 kernel/jump_label.c:123 tracepoint_add_func kernel/tracepoint.c:223 [inline] tracepoint_probe_register_prio+0x4d4/0x6d0 kernel/tracepoint.c:283 trace_event_reg+0x272/0x330 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+0x424/0xa50 kernel/trace/trace_event_perf.c:221 perf_tp_event_init+0x79/0xf0 kernel/events/core.c:8127 perf_try_init_event+0x15b/0x1f0 kernel/events/core.c:9363 perf_init_event kernel/events/core.c:9401 [inline] perf_event_alloc.part.0+0xd89/0x25a0 kernel/events/core.c:9661 perf_event_alloc kernel/events/core.c:10014 [inline] SYSC_perf_event_open+0xa80/0x24a0 kernel/events/core.c:10118 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #2 (tracepoints_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893 tracepoint_probe_register_prio+0x35/0x6d0 kernel/tracepoint.c:279 trace_event_reg+0x272/0x330 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+0x424/0xa50 kernel/trace/trace_event_perf.c:221 perf_tp_event_init+0x79/0xf0 kernel/events/core.c:8127 perf_try_init_event+0x15b/0x1f0 kernel/events/core.c:9363 perf_init_event kernel/events/core.c:9401 [inline] perf_event_alloc.part.0+0xd89/0x25a0 kernel/events/core.c:9661 perf_event_alloc kernel/events/core.c:10014 [inline] SYSC_perf_event_open+0xa80/0x24a0 kernel/events/core.c:10118 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #1 (event_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893 perf_trace_destroy+0x23/0xf0 kernel/trace/trace_event_perf.c:234 _free_event+0x328/0xe30 kernel/events/core.c:4238 free_event+0x32/0x40 kernel/events/core.c:4265 perf_event_release_kernel+0x35c/0x870 kernel/events/core.c:4409 perf_release+0x33/0x40 kernel/events/core.c:4435 __fput+0x25f/0x790 fs/file_table.c:210 task_work_run+0x113/0x190 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x9f2/0x2b00 kernel/exit.c:858 do_group_exit+0x100/0x310 kernel/exit.c:955 get_signal+0x385/0x1ca0 kernel/signal.c:2423 do_signal+0x7c/0x1690 arch/x86/kernel/signal.c:814 exit_to_usermode_loop+0x159/0x220 arch/x86/entry/common.c:160 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:270 [inline] do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #0 (&event->child_mutex){+.+.}: lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893 perf_read_group kernel/events/core.c:4536 [inline] __perf_read kernel/events/core.c:4618 [inline] perf_read+0x2a1/0x7c0 kernel/events/core.c:4633 do_loop_readv_writev fs/read_write.c:695 [inline] do_loop_readv_writev fs/read_write.c:682 [inline] do_iter_read+0x3e3/0x5a0 fs/read_write.c:919 vfs_readv+0xd3/0x130 fs/read_write.c:981 do_readv+0xfc/0x2c0 fs/read_write.c:1014 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 other info that might help us debug this: Chain exists of: &event->child_mutex --> pmus_lock --> &cpuctx_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&cpuctx_mutex); lock(pmus_lock); lock(&cpuctx_mutex); lock(&event->child_mutex); *** DEADLOCK *** 1 lock held by syz-executor.1/23031: #0: (&cpuctx_mutex){+.+.}, at: [] perf_event_ctx_lock_nested+0x14d/0x2c0 kernel/events/core.c:1235 stack backtrace: CPU: 0 PID: 23031 Comm: syz-executor.1 Not tainted 4.14.180-syzkaller #0 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+0x13e/0x194 lib/dump_stack.c:58 print_circular_bug.isra.0.cold+0x1c4/0x282 kernel/locking/lockdep.c:1258 check_prev_add kernel/locking/lockdep.c:1905 [inline] check_prevs_add kernel/locking/lockdep.c:2022 [inline] validate_chain kernel/locking/lockdep.c:2464 [inline] __lock_acquire+0x2cb3/0x4620 kernel/locking/lockdep.c:3491 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893 perf_read_group kernel/events/core.c:4536 [inline] __perf_read kernel/events/core.c:4618 [inline] perf_read+0x2a1/0x7c0 kernel/events/core.c:4633 do_loop_readv_writev fs/read_write.c:695 [inline] do_loop_readv_writev fs/read_write.c:682 [inline] do_iter_read+0x3e3/0x5a0 fs/read_write.c:919 vfs_readv+0xd3/0x130 fs/read_write.c:981 do_readv+0xfc/0x2c0 fs/read_write.c:1014 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45c829 RSP: 002b:00007f494f2efc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000013 RAX: ffffffffffffffda RBX: 00000000004fb060 RCX: 000000000045c829 RDX: 0000000000000004 RSI: 000000002058c000 RDI: 0000000000000004 RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000892 R14: 00000000004cb258 R15: 00007f494f2f06d4 ptrace attach of "/root/syz-executor.2"[23568] was attempted by "/root/syz-executor.2"[23570] ptrace attach of "/root/syz-executor.2"[23593] was attempted by "/root/syz-executor.2"[23602] ptrace attach of "/root/syz-executor.3"[23615] was attempted by "/root/syz-executor.3"[23617] ptrace attach of "/root/syz-executor.2"[23613] was attempted by "/root/syz-executor.2"[23618] sock: process `syz-executor.3' is using obsolete getsockopt SO_BSDCOMPAT netlink: 8 bytes leftover after parsing attributes in process `syz-executor.1'. ptrace attach of "/root/syz-executor.2"[23639] was attempted by "/root/syz-executor.2"[23644] device batadv0 entered promiscuous mode device macvtap1 entered promiscuous mode 8021q: adding VLAN 0 to HW filter on device macvtap1 ptrace attach of "/root/syz-executor.2"[23662] was attempted by "/root/syz-executor.2"[23670] netlink: 8 bytes leftover after parsing attributes in process `syz-executor.1'. IPVS: ftp: loaded support on port[0] = 21 device macvtap2 entered promiscuous mode 8021q: adding VLAN 0 to HW filter on device macvtap2 IPVS: ftp: loaded support on port[0] = 21 netlink: 8 bytes leftover after parsing attributes in process `syz-executor.1'. device macvtap3 entered promiscuous mode 8021q: adding VLAN 0 to HW filter on device macvtap3 netlink: 8 bytes leftover after parsing attributes in process `syz-executor.1'. device macvtap4 entered promiscuous mode 8021q: adding VLAN 0 to HW filter on device macvtap4 hfsplus: unable to find HFS+ superblock hfsplus: unable to find HFS+ superblock IPVS: ftp: loaded support on port[0] = 21 hfsplus: unable to find HFS+ superblock