Subject: INFO: task hung in reg_check_chans_work

From: syzbot <[email-masked]>
Date: Wed, 14 Feb 2018 05:59:01 -0800

Hello,

syzbot hit the following crash on upstream commit
cbd7b8a76b79a2ff6112ef2e77031b694843b8a1 (Tue Feb 6 23:30:52 2018 +0000)
Merge tag 'platform-drivers-x86-v4.16-1' of  
git://git.infradead.org/linux-platform-drivers-x86

So far this crash happened 6 times on net-next, upstream.
Unfortunately, I don't have any reproducer for this crash yet.
Raw console output is attached.
compiler: gcc (GCC) 7.1.1 20170620
.config is attached.

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Reported-by: [email-masked]
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Cannot find add_set index 2048 as target
INFO: task kworker/1:3:5678 blocked for more than 120 seconds.
       Not tainted 4.15.0+ #300
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/1:3     D22704  5678      2 0x80000000
Workqueue: events_power_efficient reg_check_chans_work
Call Trace:
  context_switch kernel/sched/core.c:2845 [inline]
  __schedule+0x8eb/0x2060 kernel/sched/core.c:3421
  schedule+0xf5/0x430 kernel/sched/core.c:3480
  schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3538
  __mutex_lock_common kernel/locking/mutex.c:833 [inline]
  __mutex_lock+0xaad/0x1a80 kernel/locking/mutex.c:893
  mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
  rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74
  reg_check_chans_work+0xaa/0xff0 net/wireless/reg.c:2017
  process_one_work+0xbbf/0x1af0 kernel/workqueue.c:2113
  worker_thread+0x223/0x1990 kernel/workqueue.c:2247
  kthread+0x33c/0x400 kernel/kthread.c:238
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:429

Showing all locks held in the system:
2 locks held by khungtaskd/759:
  #0:  (rcu_read_lock){....}, at: [<00000000d4470309>]  
check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline]
  #0:  (rcu_read_lock){....}, at: [<00000000d4470309>] watchdog+0x1c5/0xd60  
kernel/hung_task.c:249
  #1:  (tasklist_lock){.+.+}, at: [<0000000037ffdeeb>]  
debug_show_all_locks+0xd3/0x3d0 kernel/locking/lockdep.c:4470
3 locks held by kworker/0:3/1827:
  #0:  ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at:  
[<000000008982763e>] process_one_work+0xaaf/0x1af0 kernel/workqueue.c:2084
  #1:  ((addr_chk_work).work){+.+.}, at: [<00000000274eb49e>]  
process_one_work+0xb01/0x1af0 kernel/workqueue.c:2088
  #2:  (rtnl_mutex){+.+.}, at: [<00000000b75e700b>] rtnl_lock+0x17/0x20  
net/core/rtnetlink.c:74
1 lock held by rsyslogd/4013:
  #0:  (&f->f_pos_lock){+.+.}, at: [<0000000008f3ba06>]  
__fdget_pos+0x12b/0x190 fs/file.c:765
2 locks held by getty/4134:
  #0:  (&tty->ldisc_sem){++++}, at: [<00000000d8e84bec>]  
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
  #1:  (&ldata->atomic_read_lock){+.+.}, at: [<000000003438beb0>]  
n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131
2 locks held by getty/4135:
  #0:  (&tty->ldisc_sem){++++}, at: [<00000000d8e84bec>]  
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
  #1:  (&ldata->atomic_read_lock){+.+.}, at: [<000000003438beb0>]  
n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131
2 locks held by getty/4136:
  #0:  (&tty->ldisc_sem){++++}, at: [<00000000d8e84bec>]  
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
  #1:  (&ldata->atomic_read_lock){+.+.}, at: [<000000003438beb0>]  
n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131
2 locks held by getty/4137:
  #0:  (&tty->ldisc_sem){++++}, at: [<00000000d8e84bec>]  
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
  #1:  (&ldata->atomic_read_lock){+.+.}, at: [<000000003438beb0>]  
n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131
2 locks held by getty/4138:
  #0:  (&tty->ldisc_sem){++++}, at: [<00000000d8e84bec>]  
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
  #1:  (&ldata->atomic_read_lock){+.+.}, at: [<000000003438beb0>]  
n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131
2 locks held by getty/4139:
  #0:  (&tty->ldisc_sem){++++}, at: [<00000000d8e84bec>]  
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
  #1:  (&ldata->atomic_read_lock){+.+.}, at: [<000000003438beb0>]  
n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131
2 locks held by getty/4140:
  #0:  (&tty->ldisc_sem){++++}, at: [<00000000d8e84bec>]  
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
  #1:  (&ldata->atomic_read_lock){+.+.}, at: [<000000003438beb0>]  
n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131
3 locks held by kworker/1:3/5678:
  #0:  ((wq_completion)"events_power_efficient"){+.+.}, at:  
[<000000008982763e>] process_one_work+0xaaf/0x1af0 kernel/workqueue.c:2084
  #1:  ((reg_check_chans).work){+.+.}, at: [<00000000274eb49e>]  
process_one_work+0xb01/0x1af0 kernel/workqueue.c:2088
  #2:  (rtnl_mutex){+.+.}, at: [<00000000b75e700b>] rtnl_lock+0x17/0x20  
net/core/rtnetlink.c:74
1 lock held by syz-executor2/11029:
  #0:  (sk_lock-AF_INET6){+.+.}, at: [<0000000050f92c05>] lock_sock  
include/net/sock.h:1463 [inline]
  #0:  (sk_lock-AF_INET6){+.+.}, at: [<0000000050f92c05>]  
ipv6_getsockopt+0x1c5/0x2e0 net/ipv6/ipv6_sockglue.c:1370
1 lock held by syz-executor2/11040:
  #0:  (rtnl_mutex){+.+.}, at: [<00000000b75e700b>] rtnl_lock+0x17/0x20  
net/core/rtnetlink.c:74
1 lock held by syz-executor2/11047:
  #0:  (rtnl_mutex){+.+.}, at: [<00000000b75e700b>] rtnl_lock+0x17/0x20  
net/core/rtnetlink.c:74
1 lock held by syz-executor2/11051:
  #0:  (rtnl_mutex){+.+.}, at: [<00000000b75e700b>] rtnl_lock+0x17/0x20  
net/core/rtnetlink.c:74
1 lock held by syz-executor2/11054:
  #0:  (sk_lock-AF_INET6){+.+.}, at: [<0000000050f92c05>] lock_sock  
include/net/sock.h:1463 [inline]
  #0:  (sk_lock-AF_INET6){+.+.}, at: [<0000000050f92c05>]  
ipv6_getsockopt+0x1c5/0x2e0 net/ipv6/ipv6_sockglue.c:1370
1 lock held by syz-executor2/11055:
  #0:  (rtnl_mutex){+.+.}, at: [<00000000b75e700b>] rtnl_lock+0x17/0x20  
net/core/rtnetlink.c:74
1 lock held by syz-executor2/11056:
  #0:  (rtnl_mutex){+.+.}, at: [<00000000b75e700b>] rtnl_lock+0x17/0x20  
net/core/rtnetlink.c:74
1 lock held by syz-executor2/11057:
  #0:  (rtnl_mutex){+.+.}, at: [<00000000b75e700b>] rtnl_lock+0x17/0x20  
net/core/rtnetlink.c:74

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 759 Comm: khungtaskd Not tainted 4.15.0+ #300
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:17 [inline]
  dump_stack+0x194/0x257 lib/dump_stack.c:53
  nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103
  nmi_trigger_cpumask_backtrace+0x122/0x180 lib/nmi_backtrace.c:62
  arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
  trigger_all_cpu_backtrace include/linux/nmi.h:138 [inline]
  check_hung_task kernel/hung_task.c:132 [inline]
  check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline]
  watchdog+0x90c/0xd60 kernel/hung_task.c:249
  kthread+0x33c/0x400 kernel/kthread.c:238
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:429
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0x6/0x10  
arch/x86/include/asm/irqflags.h:54

---
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