INFO: task syz-executor.1:10354 can't die for more than 143 seconds. task:syz-executor.1 state:D stack:28664 pid:10354 ppid: 8887 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:3773 [inline] __schedule+0x893/0x2170 kernel/sched/core.c:4522 schedule+0xcf/0x270 kernel/sched/core.c:4600 schedule_timeout+0x1d8/0x250 kernel/time/timer.c:1847 do_wait_for_common kernel/sched/completion.c:85 [inline] __wait_for_common kernel/sched/completion.c:106 [inline] wait_for_common kernel/sched/completion.c:117 [inline] wait_for_completion+0x163/0x260 kernel/sched/completion.c:138 flush_workqueue+0x3ff/0x13e0 kernel/workqueue.c:2835 nbd_start_device_ioctl drivers/block/nbd.c:1331 [inline] __nbd_ioctl drivers/block/nbd.c:1408 [inline] nbd_ioctl+0x76d/0xbe0 drivers/block/nbd.c:1448 __blkdev_driver_ioctl block/ioctl.c:228 [inline] blkdev_ioctl+0x28b/0x700 block/ioctl.c:623 block_ioctl+0xf9/0x140 fs/block_dev.c:1869 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45deb9 Code: Unable to access opcode bytes at RIP 0x45de8f. RSP: 002b:00007fa187726c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000012f00 RCX: 000000000045deb9 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003 RBP: 000000000118c000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bfd4 R13: 00007fff019bb39f R14: 00007fa1877279c0 R15: 000000000118bfd4 INFO: task syz-executor.1:10354 blocked for more than 143 seconds. Not tainted 5.10.0-rc1-next-20201030-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.1 state:D stack:28664 pid:10354 ppid: 8887 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:3773 [inline] __schedule+0x893/0x2170 kernel/sched/core.c:4522 schedule+0xcf/0x270 kernel/sched/core.c:4600 schedule_timeout+0x1d8/0x250 kernel/time/timer.c:1847 do_wait_for_common kernel/sched/completion.c:85 [inline] __wait_for_common kernel/sched/completion.c:106 [inline] wait_for_common kernel/sched/completion.c:117 [inline] wait_for_completion+0x163/0x260 kernel/sched/completion.c:138 flush_workqueue+0x3ff/0x13e0 kernel/workqueue.c:2835 nbd_start_device_ioctl drivers/block/nbd.c:1331 [inline] __nbd_ioctl drivers/block/nbd.c:1408 [inline] nbd_ioctl+0x76d/0xbe0 drivers/block/nbd.c:1448 __blkdev_driver_ioctl block/ioctl.c:228 [inline] blkdev_ioctl+0x28b/0x700 block/ioctl.c:623 block_ioctl+0xf9/0x140 fs/block_dev.c:1869 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45deb9 Code: Unable to access opcode bytes at RIP 0x45de8f. RSP: 002b:00007fa187726c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000012f00 RCX: 000000000045deb9 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003 RBP: 000000000118c000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bfd4 R13: 00007fff019bb39f R14: 00007fa1877279c0 R15: 000000000118bfd4 Showing all locks held in the system: 1 lock held by khungtaskd/1655: #0: ffffffff8b337f60 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6253 2 locks held by in:imklog/8188: #0: ffff88801a8bb270 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:932 #1: ffffffff8b337f60 (rcu_read_lock){....}-{1:2}, at: rq_lock kernel/sched/sched.h:1292 [inline] #1: ffffffff8b337f60 (rcu_read_lock){....}-{1:2}, at: ttwu_queue kernel/sched/core.c:2694 [inline] #1: ffffffff8b337f60 (rcu_read_lock){....}-{1:2}, at: try_to_wake_up+0x535/0x1300 kernel/sched/core.c:2974 2 locks held by kworker/u5:3/8900: #0: ffff888028f71138 ((wq_completion)knbd1-recv){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff888028f71138 ((wq_completion)knbd1-recv){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline] #0: ffff888028f71138 ((wq_completion)knbd1-recv){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline] #0: ffff888028f71138 ((wq_completion)knbd1-recv){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline] #0: ffff888028f71138 ((wq_completion)knbd1-recv){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #0: ffff888028f71138 ((wq_completion)knbd1-recv){+.+.}-{0:0}, at: process_one_work+0x821/0x15a0 kernel/workqueue.c:2243 #1: ffffc90001c6fda8 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x854/0x15a0 kernel/workqueue.c:2247 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1655 Comm: khungtaskd Not tainted 5.10.0-rc1-next-20201030-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+0x107/0x163 lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:147 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:253 [inline] watchdog+0xd89/0xf30 kernel/hung_task.c:338 kthread+0x3af/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 8713 Comm: kworker/1:4 Not tainted 5.10.0-rc1-next-20201030-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+0xa/0x5590 kernel/locking/lockdep.c:4689 Code: 09 ed 8c e8 b8 f7 5b 00 e9 46 ff ff ff 48 c7 c7 58 09 ed 8c e8 a7 f7 5b 00 e9 58 fe ff ff 66 90 41 57 41 89 cf 41 56 49 89 fe <41> 55 41 89 d5 41 54 55 89 f5 53 44 89 c3 48 81 ec e8 00 00 00 48 RSP: 0018:ffffc9000242f9d8 EFLAGS: 00000002 RAX: 0000000000000001 RBX: 1ffff92000485f44 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88801019fb60 RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000001 R10: fffffbfff19d9af1 R11: 0000000024d1c2bd R12: 0000000000000000 R13: ffff88801019fb60 R14: ffff88801019fb60 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8880b9f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f8f8f8f2000 CR3: 00000000117bd000 CR4: 00000000001506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire kernel/locking/lockdep.c:5436 [inline] lock_acquire+0x1af/0x8b0 kernel/locking/lockdep.c:5401 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:159 _crng_backtrack_protect+0x71/0x1a0 drivers/char/random.c:1045 crng_backtrack_protect drivers/char/random.c:1063 [inline] _get_random_bytes+0x295/0x670 drivers/char/random.c:1564 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:533 [inline] nsim_dev_trap_report drivers/net/netdevsim/dev.c:562 [inline] nsim_dev_trap_report_work+0x74e/0xbd0 drivers/net/netdevsim/dev.c:603 process_one_work+0x933/0x15a0 kernel/workqueue.c:2272 worker_thread+0x64c/0x1120 kernel/workqueue.c:2418 kthread+0x3af/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296