FS-Cache: N-key=[10] '0200020000807f000008'
FS-Cache: Duplicate cookie detected
------------[ cut here ]------------
FS-Cache: O-cookie c=00000000ca3dda19 [p=00000000d6d0b531 fl=222 nc=0 na=1]
ODEBUG: free active (active state 0) object type: timer_list hint: xprt_init_autodisconnect+0x0/0x230 net/sunrpc/xprt.c:109
WARNING: CPU: 1 PID: 6042 at lib/debugobjects.c:328 debug_print_object+0x16a/0x210 lib/debugobjects.c:325
FS-Cache: O-cookie d=000000004c9c0324 n=0000000060c9bc7d
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 6042 Comm: syz-executor4 Not tainted 4.20.0-rc6-next-20181217+ #172
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
FS-Cache: O-key=[10] '0200020000807f000008'
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x244/0x39d lib/dump_stack.c:113
 panic+0x2ad/0x632 kernel/panic.c:214
FS-Cache: N-cookie c=000000004f347301 [p=00000000d6d0b531 fl=2 nc=0 na=1]
FS-Cache: N-cookie d=000000004c9c0324 n=000000004af4ceb8
 __warn.cold.8+0x20/0x4f kernel/panic.c:571
FS-Cache: N-key=[10] '0200020000807f000008'
 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:973
FS-Cache: Duplicate cookie detected
RIP: 0010:debug_print_object+0x16a/0x210 lib/debugobjects.c:325
Code: 81 88 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 92 00 00 00 48 8b 14 dd e0 0c 81 88 4c 89 fe 48 c7 c7 80 02 81 88 e8 76 87 b4 fd <0f> 0b 83 05 11 a2 a2 06 01 48 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f
RSP: 0018:ffff8881dad07838 EFLAGS: 00010086
FS-Cache: O-cookie c=00000000ca3dda19 [p=00000000d6d0b531 fl=222 nc=0 na=1]
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000000
RDX: 0000000000000100 RSI: ffffffff8166b045 RDI: 0000000000000005
RBP: ffff8881dad07878 R08: ffff8881c1b681c0 R09: fffffbfff12f2e44
R10: fffffbfff12f2e44 R11: ffffffff89797223 R12: 0000000000000001
R13: ffffffff897ab5a0 R14: ffffffff816d0780 R15: ffffffff88810720
FS-Cache: O-cookie d=000000004c9c0324 n=0000000060c9bc7d
FS-Cache: O-key=[10] '0200020000807f000008'
 __debug_check_no_obj_freed lib/debugobjects.c:785 [inline]
 debug_check_no_obj_freed+0x3ae/0x58d lib/debugobjects.c:817
FS-Cache: N-cookie c=0000000023e63ac4 [p=00000000d6d0b531 fl=2 nc=0 na=1]
 kfree+0xbd/0x230 mm/slab.c:3803
 __rcu_reclaim kernel/rcu/rcu.h:233 [inline]
 rcu_do_batch kernel/rcu/tree.c:2452 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2773 [inline]
 rcu_process_callbacks+0xd91/0x15f0 kernel/rcu/tree.c:2754
FS-Cache: N-cookie d=000000004c9c0324 n=00000000c5c8d690
FS-Cache: N-key=[10] '0200020000807f000008'
 __do_softirq+0x308/0xb7e kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0x17f/0x1c0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:536 [inline]
 smp_apic_timer_interrupt+0x1cb/0x760 arch/x86/kernel/apic/apic.c:1062
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807
 </IRQ>
RIP: 0010:do_syscall_64+0x1a3/0x820 arch/x86/entry/common.c:290
Code: 48 81 fb 24 02 00 00 48 19 c0 48 21 c3 48 b8 00 00 00 00 00 fc ff df 48 8d 3c dd a0 45 40 88 48 89 fa 48 c1 ea 03 80 3c 02 00 <0f> 85 b2 05 00 00 4c 89 f7 48 8b 04 dd a0 45 40 88 e8 f7 9e 1f 07
RSP: 0018:ffff8881c106fe30 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: dffffc0000000000 RBX: 000000000000003d RCX: ffffffff8100c3fb
RDX: 1ffffffff10808f1 RSI: ffffffff8100c409 RDI: ffffffff88404788
RBP: ffff8881c106ff48 R08: ffff8881c1b681c0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff1103820dfc8
R13: ffff8881c106ff20 R14: ffff8881c106ff58 R15: dffffc0000000000
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x41134a
Code: 0f 83 1a 17 00 00 c3 66 0f 1f 84 00 00 00 00 00 8b 05 6e 4c 63 00 85 c0 75 36 45 31 d2 48 63 d2 48 63 ff b8 3d 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 06 c3 0f 1f 44 00 00 48 c7 c2 d4 ff ff ff f7
RSP: 002b:00007ffeffd8a578 EFLAGS: 00000246 ORIG_RAX: 000000000000003d
RAX: ffffffffffffffda RBX: 00000000000a2f3f RCX: 000000000041134a
RDX: 0000000040000001 RSI: 00007ffeffd8a5b0 RDI: ffffffffffffffff
RBP: 00000000000005b2 R08: 0000000000000001 R09: 0000000002125940
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 00000000000a2f06 R14: 000000000000012d R15: 0000000000000004

======================================================
WARNING: possible circular locking dependency detected
4.20.0-rc6-next-20181217+ #172 Not tainted
------------------------------------------------------
syz-executor4/6042 is trying to acquire lock:
00000000f22164da ((console_sem).lock){-.-.}, at: down_trylock+0x13/0x70 kernel/locking/semaphore.c:136

but task is already holding lock:
000000007445c475 (&obj_hash[i].lock){-.-.}, at: __debug_check_no_obj_freed lib/debugobjects.c:776 [inline]
000000007445c475 (&obj_hash[i].lock){-.-.}, at: debug_check_no_obj_freed+0x17a/0x58d lib/debugobjects.c:817

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&obj_hash[i].lock){-.-.}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x99/0xd0 kernel/locking/spinlock.c:152
       __debug_object_init+0x127/0x1290 lib/debugobjects.c:383
       debug_object_init+0x16/0x20 lib/debugobjects.c:431
       debug_hrtimer_init kernel/time/hrtimer.c:401 [inline]
       debug_init kernel/time/hrtimer.c:449 [inline]
       hrtimer_init+0x97/0x490 kernel/time/hrtimer.c:1299
       init_dl_task_timer+0x1b/0x50 kernel/sched/deadline.c:1057
       __sched_fork+0x2ae/0x590 kernel/sched/core.c:2166
       init_idle+0x75/0x740 kernel/sched/core.c:5374
       sched_init+0xb33/0xc07 kernel/sched/core.c:6063
       start_kernel+0x4c6/0x9e0 init/main.c:608
       x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:470
       x86_64_start_kernel+0x76/0x79 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+0x2d/0x40 kernel/locking/spinlock.c:144
       rq_lock kernel/sched/sched.h:1149 [inline]
       task_fork_fair+0xb0/0x6d0 kernel/sched/fair.c:10083
       sched_fork+0x443/0xba0 kernel/sched/core.c:2359
       copy_process+0x25b9/0x87a0 kernel/fork.c:1883
       _do_fork+0x1cb/0x11d0 kernel/fork.c:2212
       kernel_thread+0x34/0x40 kernel/fork.c:2271
       rest_init+0x28/0x372 init/main.c:408
       arch_call_rest_init+0xe/0x1b
       start_kernel+0x9a5/0x9e0 init/main.c:740
       x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:470
       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/0x1440 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+0x811/0x1190 kernel/printk/printk.c:2430
       vprintk_emit+0x391/0x990 kernel/printk/printk.c:1935
       vprintk_default+0x28/0x30 kernel/printk/printk.c:1962
       vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398
       printk+0xa7/0xcf kernel/printk/printk.c:1995
       fill_kobj_path lib/kobject.c:151 [inline]
       kobject_get_path.cold.8+0x38/0x47 lib/kobject.c:174
       kobject_uevent_env+0x314/0x101e lib/kobject_uevent.c:521
       call_crda net/wireless/reg.c:556 [inline]
       reg_query_database+0x283/0x400 net/wireless/reg.c:1104
       reg_process_hint_core net/wireless/reg.c:2339 [inline]
       reg_process_hint+0x189/0xec0 net/wireless/reg.c:2677
       reg_process_pending_hints net/wireless/reg.c:2767 [inline]
       reg_todo+0x49a/0xc20 net/wireless/reg.c:2844
       process_one_work+0xc90/0x1c40 kernel/workqueue.c:2153
       worker_thread+0x17f/0x1390 kernel/workqueue.c:2296
       kthread+0x35a/0x440 kernel/kthread.c:246
       ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

-> #0 ((console_sem).lock){-.-.}:
       lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3841
       __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:2245
       console_trylock_spinning kernel/printk/printk.c:1666 [inline]
       vprintk_emit+0x372/0x990 kernel/printk/printk.c:1934
       vprintk_default+0x28/0x30 kernel/printk/printk.c:1962
       vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398
       printk+0xa7/0xcf kernel/printk/printk.c:1995
       __warn_printk+0x8c/0xe0 kernel/panic.c:625
       debug_print_object+0x16a/0x210 lib/debugobjects.c:325
       __debug_check_no_obj_freed lib/debugobjects.c:785 [inline]
       debug_check_no_obj_freed+0x3ae/0x58d lib/debugobjects.c:817
       kfree+0xbd/0x230 mm/slab.c:3803
       __rcu_reclaim kernel/rcu/rcu.h:233 [inline]
       rcu_do_batch kernel/rcu/tree.c:2452 [inline]
       invoke_rcu_callbacks kernel/rcu/tree.c:2773 [inline]
       rcu_process_callbacks+0xd91/0x15f0 kernel/rcu/tree.c:2754
       __do_softirq+0x308/0xb7e kernel/softirq.c:292
       invoke_softirq kernel/softirq.c:373 [inline]
       irq_exit+0x17f/0x1c0 kernel/softirq.c:413
       exiting_irq arch/x86/include/asm/apic.h:536 [inline]
       smp_apic_timer_interrupt+0x1cb/0x760 arch/x86/kernel/apic/apic.c:1062
       apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807
       do_syscall_64+0x1a3/0x820 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 --> &rq->lock --> &obj_hash[i].lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&obj_hash[i].lock);
                               lock(&rq->lock);
                               lock(&obj_hash[i].lock);
  lock((console_sem).lock);

 *** DEADLOCK ***

2 locks held by syz-executor4/6042:
 #0: 00000000909e16d2 (rcu_callback){....}, at: __rcu_reclaim kernel/rcu/rcu.h:228 [inline]
 #0: 00000000909e16d2 (rcu_callback){....}, at: rcu_do_batch kernel/rcu/tree.c:2452 [inline]
 #0: 00000000909e16d2 (rcu_callback){....}, at: invoke_rcu_callbacks kernel/rcu/tree.c:2773 [inline]
 #0: 00000000909e16d2 (rcu_callback){....}, at: rcu_process_callbacks+0xd54/0x15f0 kernel/rcu/tree.c:2754
 #1: 000000007445c475 (&obj_hash[i].lock){-.-.}, at: __debug_check_no_obj_freed lib/debugobjects.c:776 [inline]
 #1: 000000007445c475 (&obj_hash[i].lock){-.-.}, at: debug_check_no_obj_freed+0x17a/0x58d lib/debugobjects.c:817

stack backtrace:
CPU: 1 PID: 6042 Comm: syz-executor4 Not tainted 4.20.0-rc6-next-20181217+ #172
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x244/0x39d lib/dump_stack.c:113
 print_circular_bug.isra.36.cold.58+0x1bd/0x27d kernel/locking/lockdep.c:1224
 check_prev_add kernel/locking/lockdep.c:1866 [inline]
 check_prevs_add kernel/locking/lockdep.c:1979 [inline]
 validate_chain kernel/locking/lockdep.c:2350 [inline]
 __lock_acquire+0x3399/0x4c20 kernel/locking/lockdep.c:3338
 lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3841
 __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:2245
 console_trylock_spinning kernel/printk/printk.c:1666 [inline]
 vprintk_emit+0x372/0x990 kernel/printk/printk.c:1934
 vprintk_default+0x28/0x30 kernel/printk/printk.c:1962
 vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398
 printk+0xa7/0xcf kernel/printk/printk.c:1995
 __warn_printk+0x8c/0xe0 kernel/panic.c:625
 debug_print_object+0x16a/0x210 lib/debugobjects.c:325
 __debug_check_no_obj_freed lib/debugobjects.c:785 [inline]
 debug_check_no_obj_freed+0x3ae/0x58d lib/debugobjects.c:817
 kfree+0xbd/0x230 mm/slab.c:3803
 __rcu_reclaim kernel/rcu/rcu.h:233 [inline]
 rcu_do_batch kernel/rcu/tree.c:2452 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2773 [inline]
 rcu_process_callbacks+0xd91/0x15f0 kernel/rcu/tree.c:2754
 __do_softirq+0x308/0xb7e kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0x17f/0x1c0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:536 [inline]
 smp_apic_timer_interrupt+0x1cb/0x760 arch/x86/kernel/apic/apic.c:1062
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807
 </IRQ>
RIP: 0010:do_syscall_64+0x1a3/0x820 arch/x86/entry/common.c:290
Code: 48 81 fb 24 02 00 00 48 19 c0 48 21 c3 48 b8 00 00 00 00 00 fc ff df 48 8d 3c dd a0 45 40 88 48 89 fa 48 c1 ea 03 80 3c 02 00 <0f> 85 b2 05 00 00 4c 89 f7 48 8b 04 dd a0 45 40 88 e8 f7 9e 1f 07
RSP: 0018:ffff8881c106fe30 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: dffffc0000000000 RBX: 000000000000003d RCX: ffffffff8100c3fb
RDX: 1ffffffff10808f1 RSI: ffffffff8100c409 RDI: ffffffff88404788
RBP: ffff8881c106ff48 R08: ffff8881c1b681c0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff1103820dfc8
R13: ffff8881c106ff20 R14: ffff8881c106ff58 R15: dffffc0000000000
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x41134a
Code: 0f 83 1a 17 00 00 c3 66 0f 1f 84 00 00 00 00 00 8b 05 6e 4c 63 00 85 c0 75 36 45 31 d2 48 63 d2 48 63 ff b8 3d 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 06 c3 0f 1f 4
Lost 7 message(s)!
Kernel Offset: disabled
Rebooting in 86400 seconds..