syzbot

INFO: task :14693 can't die for more than 143 seconds.
                R  running task    29488 14693   8855 0x00004006
Call Trace:
 context_switch kernel/sched/core.c:3388 [inline]
 __schedule+0x8e9/0x1f30 kernel/sched/core.c:4081

Showing all locks held in the system:
1 lock held by khungtaskd/1055:
 #0: ffffffff88faccc0 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279 kernel/locking/lockdep.c:5334
1 lock held by rsyslogd/8712:
 #0: ffff8880a04651a0 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801
2 locks held by getty/8802:
 #0: ffff8880943e2090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc90005ef92e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/8803:
 #0: ffff888098fbb090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc90005f212e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/8804:
 #0: ffff888097df8090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc90005f292e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/8805:
 #0: ffff8880a11d9090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc90005f192e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/8806:
 #0: ffff888099d6c090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc90005f252e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/8807:
 #0: ffff8880928e7090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc90005f1d2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/8808:
 #0: ffff888099cae090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc90005ef12e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156

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

NMI backtrace for cpu 0
CPU: 0 PID: 1055 Comm: khungtaskd Not tainted 5.4.0-rc7-next-20191115 #0
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+0x197/0x210 lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x23b/0x28b 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:146 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:269 [inline]
 watchdog+0xc8f/0x1350 kernel/hung_task.c:353
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 17 Comm: kworker/1:0 Not tainted 5.4.0-rc7-next-20191115 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events nsim_dev_trap_report_work
RIP: 0010:_crng_backtrack_protect+0x7e/0x140 drivers/char/random.c:1103
Code: f5 dc fd 49 8d 45 48 45 31 e4 48 89 45 d0 4d 8d 75 10 48 89 c7 49 bd 00 00 00 00 00 fc ff df e8 d8 40 c3 03 48 89 45 c8 eb 03 <4d> 89 fe e8 3a f5 dc fd 48 89 df 48 83 c3 04 48 89 f8 48 c1 e8 03
RSP: 0018:ffff8880a9907b10 EFLAGS: 00000093
RAX: 0000000000000000 RBX: ffff8880a9907bc8 RCX: ffffffff8396e467
RDX: 0000000000000003 RSI: 0000000000000008 RDI: 0000000000000005
RBP: ffff8880a9907b50 R08: ffff8880a98f8480 R09: ffffed1015320f4f
R10: ffffed1015320f4e R11: 0000000000000003 R12: 0000000000000003
R13: dffffc0000000000 R14: ffff8880a1b07b18 R15: ffff8880a1b07b1c
FS:  0000000000000000(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffff600400 CR3: 0000000095833000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 crng_backtrack_protect+0x65/0x80 drivers/char/random.c:1117
 _get_random_bytes+0x19e/0x430 drivers/char/random.c:1720
 get_random_bytes+0x35/0x40 drivers/char/random.c:1731
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:349 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:373 [inline]
 nsim_dev_trap_report_work+0x6f2/0xaf0 drivers/net/netdevsim/dev.c:412
 process_one_work+0x9af/0x1740 kernel/workqueue.c:2264
 worker_thread+0x98/0xe40 kernel/workqueue.c:2410
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352