INFO: task syz-executor.3:29628 blocked for more than 143 seconds. Not tainted 5.4.0-rc3+ #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D28464 29628 7955 0x00004004 Call Trace: context_switch kernel/sched/core.c:3384 [inline] __schedule+0x74b/0xb80 kernel/sched/core.c:4069 schedule+0x131/0x1e0 kernel/sched/core.c:4136 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+0x60d/0x14b0 kernel/workqueue.c:2826 nbd_start_device_ioctl drivers/block/nbd.c:1272 [inline] __nbd_ioctl drivers/block/nbd.c:1347 [inline] nbd_ioctl+0x9d2/0xac0 drivers/block/nbd.c:1387 __blkdev_driver_ioctl block/ioctl.c:304 [inline] blkdev_ioctl+0x807/0x2980 block/ioctl.c:606 block_ioctl+0xbd/0x100 fs/block_dev.c:1954 do_vfs_ioctl+0x744/0x1730 fs/ioctl.c:46 ksys_ioctl fs/ioctl.c:713 [inline] __do_sys_ioctl fs/ioctl.c:720 [inline] __se_sys_ioctl fs/ioctl.c:718 [inline] __x64_sys_ioctl+0xe3/0x120 fs/ioctl.c:718 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x459a59 Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <90> 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 RSP: 002b:00007f4c2773bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 0000000000459a59 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000005 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f4c2773c6d4 R13: 00000000004c3381 R14: 00000000004d70b8 R15: 00000000ffffffff Showing all locks held in the system: 1 lock held by khungtaskd/1070: #0: ffffffff888d3f80 (rcu_read_lock){....}, at: rcu_lock_acquire+0x4/0x30 include/linux/rcupdate.h:207 2 locks held by getty/7910: #0: ffff88809a2fc090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272 #1: ffffc90005f212e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x221/0x1b00 drivers/tty/n_tty.c:2156 2 locks held by getty/7911: #0: ffff888095fb4090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272 #1: ffffc90005f3f2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x221/0x1b00 drivers/tty/n_tty.c:2156 2 locks held by getty/7912: #0: ffff88809a712090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272 #1: ffffc90005f252e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x221/0x1b00 drivers/tty/n_tty.c:2156 2 locks held by getty/7913: #0: ffff8880a8724090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272 #1: ffffc90005f3b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x221/0x1b00 drivers/tty/n_tty.c:2156 2 locks held by getty/7914: #0: ffff8880988c9090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272 #1: ffffc90005f432e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x221/0x1b00 drivers/tty/n_tty.c:2156 2 locks held by getty/7915: #0: ffff88809ddf7090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272 #1: ffffc90005f372e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x221/0x1b00 drivers/tty/n_tty.c:2156 2 locks held by getty/7916: #0: ffff8880a7e5f090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272 #1: ffffc90005f112e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x221/0x1b00 drivers/tty/n_tty.c:2156 3 locks held by kworker/u4:6/12471: #0: ffff8880aea34998 (&rq->lock){-.-.}, at: newidle_balance+0x629/0xb60 kernel/sched/fair.c:9825 #1: ffffffff888d3f80 (rcu_read_lock){....}, at: rcu_lock_acquire+0xd/0x40 include/linux/rcupdate.h:208 #2: ffff8880aea24a98 (&base->lock){-.-.}, at: lock_timer_base kernel/time/timer.c:936 [inline] #2: ffff8880aea24a98 (&base->lock){-.-.}, at: __mod_timer+0x1a1/0x1590 kernel/time/timer.c:1008 2 locks held by kworker/u5:1/13648: #0: ffff888099c7ad28 ((wq_completion)knbd3-recv){+.+.}, at: spin_unlock_irq include/linux/spinlock.h:388 [inline] #0: ffff888099c7ad28 ((wq_completion)knbd3-recv){+.+.}, at: process_one_work+0x75d/0x10e0 kernel/workqueue.c:2242 #1: ffff88805d627d78 ((work_completion)(&args->work)){+.+.}, at: process_one_work+0x79f/0x10e0 kernel/workqueue.c:2244 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1070 Comm: khungtaskd Not tainted 5.4.0-rc3+ #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+0x1d8/0x2f8 lib/dump_stack.c:113 nmi_cpu_backtrace+0xaf/0x1a0 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x174/0x290 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+0xbb9/0xbd0 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 skipped: idling at native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60