INFO: task syz-executor.2:8890 blocked for more than 143 seconds. Not tainted 5.6.0-rc3-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D27816 8890 8616 0x00004004 Call Trace: context_switch kernel/sched/core.c:3380 [inline] __schedule+0x87f/0xcd0 kernel/sched/core.c:4080 schedule+0x188/0x210 kernel/sched/core.c:4154 schedule_timeout+0x46/0x240 kernel/time/timer.c:1871 do_wait_for_common+0x2e7/0x4d0 kernel/sched/completion.c:83 __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common kernel/sched/completion.c:115 [inline] wait_for_completion+0x47/0x60 kernel/sched/completion.c:136 flush_workqueue+0x751/0x1820 kernel/workqueue.c:2827 nbd_start_device_ioctl drivers/block/nbd.c:1311 [inline] __nbd_ioctl drivers/block/nbd.c:1386 [inline] nbd_ioctl+0x934/0xb10 drivers/block/nbd.c:1426 __blkdev_driver_ioctl block/ioctl.c:321 [inline] blkdev_ioctl+0x2b8/0x5f0 block/ioctl.c:717 block_ioctl+0xbd/0x100 fs/block_dev.c:1983 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl fs/ioctl.c:763 [inline] __do_sys_ioctl fs/ioctl.c:772 [inline] __se_sys_ioctl+0x113/0x190 fs/ioctl.c:770 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:770 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45c449 Code: Bad RIP value. RSP: 002b:00007fbed37d0c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fbed37d16d4 RCX: 000000000045c449 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003 RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000402 R14: 00000000004c65d9 R15: 000000000076bf2c Showing all locks held in the system: 1 lock held by khungtaskd/1085: #0: ffffffff892d9908 (rcu_read_lock){....}, at: rcu_lock_acquire+0x4/0x30 include/linux/rcupdate.h:207 2 locks held by kworker/u5:0/1618: #0: ffff88809223f528 ((wq_completion)knbd2-recv){+.+.}, at: spin_unlock_irq include/linux/spinlock.h:388 [inline] #0: ffff88809223f528 ((wq_completion)knbd2-recv){+.+.}, at: process_one_work+0x763/0x10f0 kernel/workqueue.c:2237 #1: ffffc90005827d78 ((work_completion)(&args->work)){+.+.}, at: process_one_work+0x7a5/0x10f0 kernel/workqueue.c:2239 1 lock held by rsyslogd/8478: #0: ffff8880a7641120 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x279/0x310 fs/file.c:821 2 locks held by getty/8568: #0: ffff8880a76cd090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc90005ed32e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8569: #0: ffff88809ae5f090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc90005f632e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8570: #0: ffff88808ad22090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc90005ee32e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8571: #0: ffff88808c4db090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc90005f332e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8572: #0: ffff888098172090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc90005f232e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8573: #0: ffff888096f6a090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc90005f432e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8574: #0: ffff8880a6d7a090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc90005e9b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1085 Comm: khungtaskd Not tainted 5.6.0-rc3-syzkaller #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+0x1fb/0x318 lib/dump_stack.c:118 nmi_cpu_backtrace+0xaa/0x190 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x16f/0x290 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x10/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace+0x17/0x20 include/linux/nmi.h:146 check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline] watchdog+0xd40/0xd60 kernel/hung_task.c:289 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.6.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events nsim_dev_trap_report_work RIP: 0010:__lock_acquire+0x8f3/0x1bc0 kernel/locking/lockdep.c:3949 Code: d4 01 f3 44 29 e6 44 01 e3 41 c1 c4 04 41 31 f4 49 c1 e4 20 48 c7 c0 c4 ea 69 89 48 c1 e8 03 8a 04 38 84 c0 0f 85 35 0d 00 00 <49> 09 dc 83 3d a7 13 0e 08 00 48 8b 5c 24 18 48 8b 74 24 30 0f 85 RSP: 0018:ffffc90000cbf900 EFLAGS: 00000046 RAX: 1ffffffff12d3d00 RBX: 00000000a0b542df RCX: 000000005f8e681b RDX: 000000004e339fc4 RSI: 00000000cc0671d0 RDI: dffffc0000000000 RBP: ffffc90000cbfa58 R08: dffffc0000000000 R09: fffffbfff1406529 R10: fffffbfff1406529 R11: 0000000000000000 R12: 1de2b48800000000 R13: ffff8880a999e9d0 R14: 0000000000000004 R15: ffff8880a999e140 FS: 0000000000000000(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 000000008fad2000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x154/0x250 kernel/locking/lockdep.c:4484 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa1/0xc0 kernel/locking/spinlock.c:159 _extract_crng+0xf6/0x3a0 drivers/char/random.c:979 extract_crng drivers/char/random.c:998 [inline] _get_random_bytes+0x166/0x1c0 drivers/char/random.c:1534 get_random_bytes+0x51/0xd0 drivers/char/random.c:1547 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:351 [inline] nsim_dev_trap_report drivers/net/netdevsim/dev.c:376 [inline] nsim_dev_trap_report_work+0x67b/0xae0 drivers/net/netdevsim/dev.c:415 process_one_work+0x7f5/0x10f0 kernel/workqueue.c:2264 worker_thread+0xbbc/0x1630 kernel/workqueue.c:2410 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352