Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: rb_erase+0x1a8e/0x3550 lib/rbtree.c:463 CPU: 0 PID: 20938 Comm: syz-executor0 Not tainted 5.0.0-rc1+ #19 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: ====================================================== WARNING: possible circular locking dependency detected 5.0.0-rc1+ #19 Not tainted ------------------------------------------------------ syz-executor0/20938 is trying to acquire lock: 000000001ab01080 ((console_sem).lock){-.-.}, at: down_trylock+0x13/0x70 kernel/locking/semaphore.c:136 but task is already holding lock: 000000001abb6bb3 (hrtimer_bases.lock){-.-.}, at: hrtimer_interrupt+0xff/0x770 kernel/time/hrtimer.c:1490 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (hrtimer_bases.lock){-.-.}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:152 lock_hrtimer_base.isra.0+0x75/0x130 kernel/time/hrtimer.c:165 hrtimer_start_range_ns+0x120/0xda0 kernel/time/hrtimer.c:1104 hrtimer_start_expires include/linux/hrtimer.h:409 [inline] start_rt_bandwidth kernel/sched/rt.c:70 [inline] inc_rt_group kernel/sched/rt.c:1147 [inline] inc_rt_tasks kernel/sched/rt.c:1191 [inline] __enqueue_rt_entity kernel/sched/rt.c:1261 [inline] enqueue_rt_entity kernel/sched/rt.c:1305 [inline] enqueue_task_rt+0x95b/0x1010 kernel/sched/rt.c:1335 enqueue_task+0xb9/0x380 kernel/sched/core.c:730 __sched_setscheduler+0xe32/0x1fe0 kernel/sched/core.c:4336 _sched_setscheduler+0x218/0x340 kernel/sched/core.c:4373 sched_setscheduler+0xe/0x10 kernel/sched/core.c:4388 watchdog_dev_init+0x109/0x1db drivers/watchdog/watchdog_dev.c:1144 watchdog_init+0x81/0x294 drivers/watchdog/watchdog_core.c:355 do_one_initcall+0x129/0x937 init/main.c:888 do_initcall_level init/main.c:956 [inline] do_initcalls init/main.c:964 [inline] do_basic_setup init/main.c:982 [inline] kernel_init_freeable+0x4db/0x5ca init/main.c:1135 kernel_init+0x12/0x1c5 init/main.c:1055 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352 -> #3 (&rt_b->rt_runtime_lock){-.-.}: __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144 __enable_runtime kernel/sched/rt.c:786 [inline] rq_online_rt+0xb4/0x390 kernel/sched/rt.c:2178 set_rq_online.part.0+0xe7/0x140 kernel/sched/core.c:5666 set_rq_online kernel/sched/core.c:5772 [inline] sched_cpu_activate+0x29e/0x430 kernel/sched/core.c:5765 cpuhp_invoke_callback+0x2f6/0x2110 kernel/cpu.c:168 cpuhp_thread_fun+0x496/0x8a0 kernel/cpu.c:685 smpboot_thread_fn+0x6ab/0xa10 kernel/smpboot.c:164 kthread+0x357/0x430 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352 -> #2 (&rq->lock){-.-.}: __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144 rq_lock kernel/sched/sched.h:1149 [inline] task_fork_fair+0xb5/0x7a0 kernel/sched/fair.c:10058 sched_fork+0x437/0xb90 kernel/sched/core.c:2359 copy_process+0x1f95/0x8710 kernel/fork.c:1887 _do_fork+0x1a9/0x1170 kernel/fork.c:2227 kernel_thread+0x34/0x40 kernel/fork.c:2286 rest_init+0x28/0x37b init/main.c:408 arch_call_rest_init+0xe/0x1b start_kernel+0x882/0x8bd init/main.c:740 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:152 try_to_wake_up+0xb9/0x1480 kernel/sched/core.c:1965 wake_up_process+0x10/0x20 kernel/sched/core.c:2129 __up.isra.0+0x1c0/0x2a0 kernel/locking/semaphore.c:262 up+0x13e/0x1c0 kernel/locking/semaphore.c:187 __up_console_sem+0xb7/0x1c0 kernel/printk/printk.c:236 console_unlock+0x778/0x11e0 kernel/printk/printk.c:2426 vprintk_emit+0x370/0x960 kernel/printk/printk.c:1931 vprintk_default+0x28/0x30 kernel/printk/printk.c:1958 vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:398 printk+0xba/0xed kernel/printk/printk.c:1991 check_stack_usage kernel/exit.c:755 [inline] do_exit.cold+0x57/0x16a kernel/exit.c:916 do_group_exit+0x177/0x430 kernel/exit.c:970 __do_sys_exit_group kernel/exit.c:981 [inline] __se_sys_exit_group kernel/exit.c:979 [inline] __x64_sys_exit_group+0x44/0x50 kernel/exit.c:979 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 ((console_sem).lock){-.-.}: other info that might help us debug this: Chain exists of: (console_sem).lock --> &rt_b->rt_runtime_lock --> hrtimer_bases.lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(hrtimer_bases.lock); lock(&rt_b->rt_runtime_lock); lock(hrtimer_bases.lock); lock((console_sem).lock); *** DEADLOCK *** 3 locks held by syz-executor0/20938: #0: 00000000f77da46a (rcu_read_lock){....}, at: __skb_unlink include/linux/skbuff.h:1925 [inline] #0: 00000000f77da46a (rcu_read_lock){....}, at: __skb_dequeue include/linux/skbuff.h:1941 [inline] #0: 00000000f77da46a (rcu_read_lock){....}, at: process_backlog+0x195/0x750 net/core/dev.c:5921 #1: 00000000f77da46a (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2158 [inline] #1: 00000000f77da46a (rcu_read_lock){....}, at: ip_local_deliver_finish+0x13a/0x390 net/ipv4/ip_input.c:231 #2: 000000001abb6bb3 (hrtimer_bases.lock){-.-.}, at: hrtimer_interrupt+0xff/0x770 kernel/time/hrtimer.c:1490 stack backtrace: CPU: 0 PID: 20938 Comm: syz-executor0 Not tainted 5.0.0-rc1+ #19 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: Kernel Offset: disabled Rebooting in 86400 seconds..