====================================================== WARNING: possible circular locking dependency detected 5.2.0-rc5-next-20190617 #16 Not tainted ------------------------------------------------------ syz-executor.5/8891 is trying to acquire lock: 0000000012b57c56 ((console_sem).lock){-.-.}, at: down_trylock+0x13/0x70 kernel/locking/semaphore.c:135 but task is already holding lock: 000000005cfa719b (&base->lock){..-.}, at: lock_timer_base+0x56/0x1b0 kernel/time/timer.c:932 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&base->lock){..-.}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:159 lock_timer_base+0x56/0x1b0 kernel/time/timer.c:932 __mod_timer kernel/time/timer.c:1004 [inline] mod_timer kernel/time/timer.c:1096 [inline] add_timer+0x108/0x930 kernel/time/timer.c:1132 __queue_delayed_work+0x1af/0x270 kernel/workqueue.c:1649 queue_delayed_work_on+0x19a/0x200 kernel/workqueue.c:1674 queue_delayed_work include/linux/workqueue.h:509 [inline] schedule_delayed_work include/linux/workqueue.h:610 [inline] psi_task_change+0x53b/0x9d0 kernel/sched/psi.c:786 psi_enqueue kernel/sched/stats.h:82 [inline] enqueue_task kernel/sched/core.c:771 [inline] activate_task+0x212/0x490 kernel/sched/core.c:795 wake_up_new_task+0x526/0xc40 kernel/sched/core.c:2411 _do_fork+0x253/0xf70 kernel/fork.c:2399 kernel_thread+0xbb/0xf0 kernel/fork.c:2448 rest_init+0x28/0x37b init/main.c:417 arch_call_rest_init+0xe/0x1b start_kernel+0x854/0x893 init/main.c:761 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:470 x86_64_start_kernel+0x77/0x7b arch/x86/kernel/head64.c:451 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 -> #2 (&rq->lock){-.-.}: __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151 rq_lock kernel/sched/sched.h:1158 [inline] task_fork_fair+0x6a/0x520 kernel/sched/fair.c:9866 sched_fork+0x3af/0x900 kernel/sched/core.c:2347 copy_process+0x1abf/0x6a10 kernel/fork.c:2008 _do_fork+0x146/0xf70 kernel/fork.c:2375 kernel_thread+0xbb/0xf0 kernel/fork.c:2448 rest_init+0x28/0x37b init/main.c:417 arch_call_rest_init+0xe/0x1b start_kernel+0x854/0x893 init/main.c:761 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:470 x86_64_start_kernel+0x77/0x7b arch/x86/kernel/head64.c:451 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 -> #1 (&p->pi_lock){-.-.}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:159 try_to_wake_up+0x90/0x1460 kernel/sched/core.c:2000 wake_up_process+0x10/0x20 kernel/sched/core.c:2114 __up.isra.0+0x136/0x1a0 kernel/locking/semaphore.c:261 up+0x9c/0xe0 kernel/locking/semaphore.c:186 __up_console_sem+0xb7/0x1c0 kernel/printk/printk.c:244 console_unlock+0x663/0xec0 kernel/printk/printk.c:2481 vprintk_emit+0x2a0/0x700 kernel/printk/printk.c:1986 vprintk_default+0x28/0x30 kernel/printk/printk.c:2013 vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:386 printk+0xba/0xed kernel/printk/printk.c:2046 check_stack_usage kernel/exit.c:765 [inline] do_exit.cold+0x5d/0x254 kernel/exit.c:927 do_group_exit+0x135/0x360 kernel/exit.c:981 __do_sys_exit_group kernel/exit.c:992 [inline] __se_sys_exit_group kernel/exit.c:990 [inline] __x64_sys_exit_group+0x44/0x50 kernel/exit.c:990 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 ((console_sem).lock){-.-.}: check_prev_add kernel/locking/lockdep.c:2400 [inline] check_prevs_add kernel/locking/lockdep.c:2502 [inline] validate_chain kernel/locking/lockdep.c:2892 [inline] __lock_acquire+0x2416/0x4af0 kernel/locking/lockdep.c:3885 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4418 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:159 down_trylock+0x13/0x70 kernel/locking/semaphore.c:135 __down_trylock_console_sem+0xa8/0x210 kernel/printk/printk.c:227 console_trylock+0x15/0xa0 kernel/printk/printk.c:2297 console_trylock_spinning kernel/printk/printk.c:1706 [inline] vprintk_emit+0x283/0x700 kernel/printk/printk.c:1985 vprintk_default+0x28/0x30 kernel/printk/printk.c:2013 vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:386 printk+0xba/0xed kernel/printk/printk.c:2046 fail_dump lib/fault-inject.c:45 [inline] should_fail+0x708/0x852 lib/fault-inject.c:144 __should_failslab+0x121/0x190 mm/failslab.c:33 should_failslab+0x9/0x14 mm/slab_common.c:1638 slab_pre_alloc_hook mm/slab.h:494 [inline] slab_alloc mm/slab.c:3297 [inline] kmem_cache_alloc+0x47/0x6f0 mm/slab.c:3473 kmem_cache_zalloc include/linux/slab.h:733 [inline] fill_pool lib/debugobjects.c:134 [inline] __debug_object_init+0x7cb/0xe00 lib/debugobjects.c:380 debug_object_init lib/debugobjects.c:436 [inline] debug_object_activate+0x296/0x460 lib/debugobjects.c:518 debug_timer_activate kernel/time/timer.c:710 [inline] __mod_timer kernel/time/timer.c:1035 [inline] mod_timer kernel/time/timer.c:1096 [inline] add_timer+0x3c6/0x930 kernel/time/timer.c:1132 __queue_delayed_work+0x1af/0x270 kernel/workqueue.c:1649 queue_delayed_work_on+0x19a/0x200 kernel/workqueue.c:1674 queue_delayed_work include/linux/workqueue.h:509 [inline] schedule_delayed_work include/linux/workqueue.h:610 [inline] unaccount_event kernel/events/core.c:4329 [inline] _free_event+0xe6d/0x13a0 kernel/events/core.c:4437 put_event+0x47/0x60 kernel/events/core.c:4550 perf_event_release_kernel+0x693/0xbe0 kernel/events/core.c:4656 perf_release+0x37/0x50 kernel/events/core.c:4666 __fput+0x2ff/0x890 fs/file_table.c:280 ____fput+0x16/0x20 fs/file_table.c:313 task_work_run+0x145/0x1c0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:168 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:279 [inline] do_syscall_64+0x58e/0x680 arch/x86/entry/common.c:304 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: (console_sem).lock --> &rq->lock --> &base->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&base->lock); lock(&rq->lock); lock(&base->lock); lock((console_sem).lock); *** DEADLOCK *** 1 lock held by syz-executor.5/8891: #0: 000000005cfa719b (&base->lock){..-.}, at: lock_timer_base+0x56/0x1b0 kernel/time/timer.c:932 stack backtrace: CPU: 0 PID: 8891 Comm: syz-executor.5 Not tainted 5.2.0-rc5-next-20190617 #16 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_circular_bug.cold+0x163/0x172 kernel/locking/lockdep.c:1612 check_noncircular+0x300/0x3a0 kernel/locking/lockdep.c:1736 check_prev_add kernel/locking/lockdep.c:2400 [inline] check_prevs_add kernel/locking/lockdep.c:2502 [inline] validate_chain kernel/locking/lockdep.c:2892 [inline] __lock_acquire+0x2416/0x4af0 kernel/locking/lockdep.c:3885 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4418 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:159 down_trylock+0x13/0x70 kernel/locking/semaphore.c:135 __down_trylock_console_sem+0xa8/0x210 kernel/printk/printk.c:227 console_trylock+0x15/0xa0 kernel/printk/printk.c:2297 console_trylock_spinning kernel/printk/printk.c:1706 [inline] vprintk_emit+0x283/0x700 kernel/printk/printk.c:1985 vprintk_default+0x28/0x30 kernel/printk/printk.c:2013 vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:386 printk+0xba/0xed kernel/printk/printk.c:2046 fail_dump lib/fault-inject.c:45 [inline] should_fail+0x708/0x852 lib/fault-inject.c:144 __should_failslab+0x121/0x190 mm/failslab.c:33 should_failslab+0x9/0x14 mm/slab_common.c:1638 slab_pre_alloc_hook mm/slab.h:494 [inline] slab_alloc mm/slab.c:3297 [inline] kmem_cache_alloc+0x47/0x6f0 mm/slab.c:3473 kmem_cache_zalloc include/linux/slab.h:733 [inline] fill_pool lib/debugobjects.c:134 [inline] __debug_object_init+0x7cb/0xe00 lib/debugobjects.c:380 debug_object_init lib/debugobjects.c:436 [inline] debug_object_activate+0x296/0x460 lib/debugobjects.c:518 debug_timer_activate kernel/time/timer.c:710 [inline] __mod_timer kernel/time/timer.c:1035 [inline] mod_timer kernel/time/timer.c:1096 [inline] add_timer+0x3c6/0x930 kernel/time/timer.c:1132 __queue_delayed_work+0x1af/0x270 kernel/workqueue.c:1649 queue_delayed_work_on+0x19a/0x200 kernel/workqueue.c:1674 queue_delayed_work include/linux/workqueue.h:509 [inline] schedule_delayed_work include/linux/workqueue.h:610 [inline] unaccount_event kernel/events/core.c:4329 [inline] _free_event+0xe6d/0x13a0 kernel/events/core.c:4437 put_event+0x47/0x60 kernel/events/core.c:4550 perf_event_release_kernel+0x693/0xbe0 kernel/events/core.c:4656 perf_release+0x37/0x50 kernel/events/core.c:4666 __fput+0x2ff/0x890 fs/file_table.c:280 ____fput+0x16/0x20 fs/file_table.c:313 task_work_run+0x145/0x1c0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:168 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:279 [inline] do_syscall_64+0x58e/0x680 arch/x86/entry/common.c:304 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4592c9 Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffa0f591c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 00007ffa0f591c90 RCX: 00000000004592c9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffa0f5926d4 R13: 00000000004f8052 R14: 00000000004d0e30 R15: 0000000000000004