WARNING: CPU: 0 PID: 9864 at kernel/sched/deadline.c:628 enqueue_task_dl+0x22da/0x38a0 kernel/sched/deadline.c:1504 Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 9864 Comm: syz-executor0 Not tainted 4.20.0-rc1-next-20181109+ #110 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+0x244/0x39d lib/dump_stack.c:113 panic+0x2ad/0x55c kernel/panic.c:188 __warn.cold.8+0x20/0x45 kernel/panic.c:540 report_bug+0x254/0x2d0 lib/bug.c:186 fixup_bug arch/x86/kernel/traps.c:178 [inline] do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:271 do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:290 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:969 RIP: 0010:enqueue_task_dl+0x22da/0x38a0 kernel/sched/deadline.c:1504 Code: ff 48 8b 8d c8 fe ff ff 48 c1 e6 2a 4c 8b 9d d0 fe ff ff 8b 95 d8 fe ff ff 48 8b 85 e0 fe ff ff e9 16 e4 ff ff e8 16 eb ea ff <0f> 0b e9 17 f1 ff ff 48 8b bd e8 fe ff ff 4c 89 95 c8 fe ff ff 48 RSP: 0018:ffff8801d9607a18 EFLAGS: 00010002 RAX: 0000000000000000 RBX: ffff8801b8fc8580 RCX: ffff8801b8fc87f8 RDX: ffff8801b8fc85bc RSI: 0000000000000002 RDI: ffff8801dae2d710 RBP: ffff8801d9607b78 R08: 0000000000000001 R09: ffff8801dae00000 R10: 0000002c1e1a22a6 R11: ffff8801dae2db3b R12: 1ffff1003b2c0f4e R13: ffff8801b8fc884c R14: ffff8801dae2ccc0 R15: ffff8801dae2ccc0 enqueue_task+0x184/0x390 kernel/sched/core.c:730 __sched_setscheduler+0xe99/0x2110 kernel/sched/core.c:4336 sched_setattr kernel/sched/core.c:4394 [inline] __do_sys_sched_setattr kernel/sched/core.c:4570 [inline] __se_sys_sched_setattr kernel/sched/core.c:4549 [inline] __x64_sys_sched_setattr+0x1b2/0x2f0 kernel/sched/core.c:4549 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457569 Code: fd b3 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 b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f786b507c78 EFLAGS: 00000246 ORIG_RAX: 000000000000013a RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457569 RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000000 RBP: 000000000072bfa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f786b5086d4 R13: 00000000004c369f R14: 00000000004d5730 R15: 00000000ffffffff ====================================================== WARNING: possible circular locking dependency detected 4.20.0-rc1-next-20181109+ #110 Not tainted ------------------------------------------------------ syz-executor0/9864 is trying to acquire lock: 000000000f20b1d9 ((console_sem).lock){-.-.}, at: down_trylock+0x13/0x70 kernel/locking/semaphore.c:136 but task is already holding lock: 00000000ffe583f7 (&rq->lock){-.-.}, at: task_rq_lock+0xc5/0x2a0 kernel/sched/core.c:99 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&rq->lock){-.-.}: __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2d/0x40 kernel/locking/spinlock.c:144 rq_lock kernel/sched/sched.h:1126 [inline] task_fork_fair+0xb0/0x6d0 kernel/sched/fair.c:9777 sched_fork+0x443/0xba0 kernel/sched/core.c:2359 copy_process+0x25b9/0x8790 kernel/fork.c:1887 _do_fork+0x1cb/0x11c0 kernel/fork.c:2216 kernel_thread+0x34/0x40 kernel/fork.c:2275 rest_init+0x28/0x372 init/main.c:409 arch_call_rest_init+0xe/0x1b start_kernel+0x9f0/0xa2b init/main.c:745 x86_64_start_reservations+0x2e/0x30 arch/x86/kernel/head64.c:472 x86_64_start_kernel+0x76/0x79 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+0x99/0xd0 kernel/locking/spinlock.c:152 try_to_wake_up+0xdc/0x1490 kernel/sched/core.c:1965 wake_up_process+0x10/0x20 kernel/sched/core.c:2129 __up.isra.1+0x1c0/0x2a0 kernel/locking/semaphore.c:262 up+0x13c/0x1c0 kernel/locking/semaphore.c:187 __up_console_sem+0xbe/0x1b0 kernel/printk/printk.c:236 console_unlock+0x80c/0x1190 kernel/printk/printk.c:2432 vprintk_emit+0x391/0x990 kernel/printk/printk.c:1922 vprintk_default+0x28/0x30 kernel/printk/printk.c:1964 vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398 printk+0xa7/0xcf kernel/printk/printk.c:1997 check_stack_usage kernel/exit.c:755 [inline] do_exit.cold.18+0x71/0x16f kernel/exit.c:916 do_group_exit+0x177/0x440 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+0x3e/0x50 kernel/exit.c:979 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 ((console_sem).lock){-.-.}: lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x99/0xd0 kernel/locking/spinlock.c:152 down_trylock+0x13/0x70 kernel/locking/semaphore.c:136 __down_trylock_console_sem+0xae/0x1f0 kernel/printk/printk.c:219 console_trylock+0x15/0xa0 kernel/printk/printk.c:2247 console_trylock_spinning kernel/printk/printk.c:1653 [inline] vprintk_emit+0x372/0x990 kernel/printk/printk.c:1921 vprintk_default+0x28/0x30 kernel/printk/printk.c:1964 vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398 printk+0xa7/0xcf kernel/printk/printk.c:1997 __warn+0x9e/0x1d0 kernel/panic.c:522 report_bug+0x254/0x2d0 lib/bug.c:186 fixup_bug arch/x86/kernel/traps.c:178 [inline] do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:271 do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:290 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:969 enqueue_task_dl+0x22da/0x38a0 kernel/sched/deadline.c:1504 enqueue_task+0x184/0x390 kernel/sched/core.c:730 __sched_setscheduler+0xe99/0x2110 kernel/sched/core.c:4336 sched_setattr kernel/sched/core.c:4394 [inline] __do_sys_sched_setattr kernel/sched/core.c:4570 [inline] __se_sys_sched_setattr kernel/sched/core.c:4549 [inline] __x64_sys_sched_setattr+0x1b2/0x2f0 kernel/sched/core.c:4549 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: (console_sem).lock --> &p->pi_lock --> &rq->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&rq->lock); lock(&p->pi_lock); lock(&rq->lock); lock((console_sem).lock); *** DEADLOCK *** 3 locks held by syz-executor0/9864: #0: 00000000c86a8423 (rcu_read_lock){....}, at: __do_sys_sched_setattr kernel/sched/core.c:4563 [inline] #0: 00000000c86a8423 (rcu_read_lock){....}, at: __se_sys_sched_setattr kernel/sched/core.c:4549 [inline] #0: 00000000c86a8423 (rcu_read_lock){....}, at: __x64_sys_sched_setattr+0x146/0x2f0 kernel/sched/core.c:4549 #1: 0000000029a7284c (&p->pi_lock){-.-.}, at: task_rq_lock+0x62/0x2a0 kernel/sched/core.c:97 #2: 00000000ffe583f7 (&rq->lock){-.-.}, at: task_rq_lock+0xc5/0x2a0 kernel/sched/core.c:99 stack backtrace: CPU: 0 PID: 9864 Comm: syz-executor0 Not tainted 4.20.0-rc1-next-20181109+ #110 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+0x244/0x39d lib/dump_stack.c:113 print_circular_bug.isra.35.cold.56+0x1bd/0x27d kernel/locking/lockdep.c:1221 check_prev_add kernel/locking/lockdep.c:1863 [inline] check_prevs_add kernel/locking/lockdep.c:1976 [inline] validate_chain kernel/locking/lockdep.c:2347 [inline] __lock_acquire+0x3399/0x4c20 kernel/locking/lockdep.c:3341 lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x99/0xd0 kernel/locking/spinlock.c:152 down_trylock+0x13/0x70 kernel/locking/semaphore.c:136 __down_trylock_console_sem+0xae/0x1f0 kernel/printk/printk.c:219 console_trylock+0x15/0xa0 kernel/printk/printk.c:2247 console_trylock_spinning kernel/printk/printk.c:1653 [inline] vprintk_emit+0x372/0x990 kernel/printk/printk.c:1921 vprintk_default+0x28/0x30 kernel/printk/printk.c:1964 vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398 printk+0xa7/0xcf kernel/printk/printk.c:1997 __warn+0x9e/0x1d0 kernel/panic.c:522 report_bug+0x254/0x2d0 lib/bug.c:186 fixup_bug arch/x86/kernel/traps.c:178 [inline] do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:271 do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:290 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:969 RIP: 0010:enqueue_task_dl+0x22da/0x38a0 kernel/sched/deadline.c:1504 Code: ff 48 8b 8d c8 fe ff ff 48 c1 e6 2a 4c 8b 9d d0 fe ff ff 8b 95 d8 fe ff ff 48 8b 85 e0 fe ff ff e9 16 e4 ff ff e8 16 eb ea ff <0f> 0b e9 17 f1 ff ff 48 8b bd e8 fe ff ff 4c 89 95 c8 fe ff ff 48 RSP: 0018:ffff8801d9607a18 EFLAGS: 00010002 RAX: 0000000000000000 RBX: ffff8801b8fc8580 RCX: ffff8801b8fc87f8 RDX: ffff8801b8fc85bc RSI: 0000000000000002 RDI: ffff8801dae2d710 RBP: ffff8801d9607b78 R08: 0000000000000001 R09: ffff8801dae00000 R10: 0000002c1e1a22a6 R11: ffff8801dae2db3b R12: 1ffff1003b2c0f4e R13: ffff8801b8fc884c R14: ffff8801dae2ccc0 R15: ffff8801dae2ccc0 enqueue_task+0x184/0x390 kernel/sched/core.c:730 __sched_setscheduler+0xe99/0x2110 kernel/sched/core.c:4336 sched_setattr kernel/sched/core.c:4394 [inline] __do_sys_sched_setattr kernel/sched/core.c:4570 [inline] __se_sys_sched_setattr kernel/sched/core.c:4549 [inline] __x64_sys_sched_setattr+0x1b2/0x2f0 kernel/sched/core.c:4549 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457569 Code: fd b3 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 b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f786b507c78 EFLAGS: 00000246 ORIG_RAX: 000000000000013a RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457569 RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000000 RBP: 000000000072bfa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f786b5086d4 R13: 00000000004c369f R14: 00000000004d5730 R15: 00000000ffffffff Kernel Offset: disabled Rebooting in 86400 seconds..