====================================================== WARNING: possible circular locking dependency detected 5.2.0-rc2+ #20 Not tainted ------------------------------------------------------ syz-executor587/8935 is trying to acquire lock: 00000000215bea58 ((console_sem).lock){-.-.}, at: down_trylock+0x13/0x70 kernel/locking/semaphore.c:136 but task is already holding lock: 00000000fcf2b0ed (&base->lock){..-.}, at: __mod_timer kernel/time/timer.c:1028 [inline] 00000000fcf2b0ed (&base->lock){..-.}, at: mod_timer kernel/time/timer.c:1096 [inline] 00000000fcf2b0ed (&base->lock){..-.}, at: add_timer+0x2e0/0x930 kernel/time/timer.c:1132 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+0x508/0xbc0 kernel/sched/core.c:2411 _do_fork+0x357/0xfe0 kernel/fork.c:2394 kernel_thread+0x34/0x40 kernel/fork.c:2428 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:1168 [inline] task_fork_fair+0x6a/0x520 kernel/sched/fair.c:10208 sched_fork+0x3af/0x900 kernel/sched/core.c:2347 copy_process.part.0+0x1a25/0x6790 kernel/fork.c:2002 copy_process kernel/fork.c:1800 [inline] _do_fork+0x25d/0xfe0 kernel/fork.c:2369 kernel_thread+0x34/0x40 kernel/fork.c:2428 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+0x90/0x13f0 kernel/sched/core.c:2000 wake_up_process+0x10/0x20 kernel/sched/core.c:2114 __up.isra.0+0x136/0x1a0 kernel/locking/semaphore.c:262 up+0x9c/0xe0 kernel/locking/semaphore.c:187 __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+0x135/0x370 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){-.-.}: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4303 __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:136 __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:32 should_failslab+0x9/0x14 mm/slab_common.c:1610 slab_pre_alloc_hook mm/slab.h:420 [inline] slab_alloc mm/slab.c:3312 [inline] kmem_cache_alloc+0x47/0x6f0 mm/slab.c:3488 kmem_cache_zalloc include/linux/slab.h:732 [inline] fill_pool lib/debugobjects.c:134 [inline] __debug_object_init+0x755/0xc30 lib/debugobjects.c:379 debug_object_init lib/debugobjects.c:431 [inline] debug_object_activate+0x2b1/0x4e0 lib/debugobjects.c:512 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-executor587/8935: #0: 00000000fcf2b0ed (&base->lock){..-.}, at: __mod_timer kernel/time/timer.c:1028 [inline] #0: 00000000fcf2b0ed (&base->lock){..-.}, at: mod_timer kernel/time/timer.c:1096 [inline] #0: 00000000fcf2b0ed (&base->lock){..-.}, at: add_timer+0x2e0/0x930 kernel/time/timer.c:1132 stack backtrace: CPU: 1 PID: 8935 Comm: syz-executor587 Not tainted 5.2.0-rc2+ #20 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+0x1cc/0x28f kernel/locking/lockdep.c:1565 check_prev_add kernel/locking/lockdep.c:2310 [inline] check_prevs_add kernel/locking/lockdep.c:2418 [inline] validate_chain kernel/locking/lockdep.c:2800 [inline] __lock_acquire+0x3755/0x5490 kernel/locking/lockdep.c:3793 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4303 __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:136 __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:32 should_failslab+0x9/0x14 mm/slab_common.c:1610 slab_pre_alloc_hook mm/slab.h:420 [inline] slab_alloc mm/slab.c:3312 [inline] kmem_cache_alloc+0x47/0x6f0 mm/slab.c:3488 kmem_cache_zalloc include/linux/slab.h:732 [inline] fill_pool lib/debugobjects.c:134 [inline] __debug_object_init+0x755/0xc30 lib/debugobjects.c:379 debug_object_init lib/debugobjects.c:431 [inline] debug_object_activate+0x2b1/0x4e0 lib/debugobjects.c:512 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: 0033:0x449f29 Code: e8 7c e6 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 1b 05 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ff28d2b6cb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 00007ff28d2b6cc0 RCX: 0000000000449f29 RDX: 0000000000000001 RSI: 0000000080808000 RDI: 0000000000000003 RBP: 0000000000000004 R08: 0000000000000001 R09: 0000000000000031 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006e6a1c R13: 00007ffcb0fa81ff R14: 00007ff28d2b79c0 R15: 20c49ba5e353f7cf