INFO: task syz-executor.0:4417 can't die for more than 143 seconds. task:syz-executor.0 state:D stack:28472 pid: 4417 ppid: 6852 flags:0x10004004 Call Trace: context_switch kernel/sched/core.c:3777 [inline] __schedule+0xec5/0x2200 kernel/sched/core.c:4526 schedule+0xcf/0x270 kernel/sched/core.c:4604 schedule_timeout+0x1d8/0x250 kernel/time/timer.c:1855 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:2832 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+0x2a7/0x7f0 block/ioctl.c:623 block_ioctl+0xf9/0x140 fs/block_dev.c:1866 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: 0033:0x45dd99 Code: Bad RIP value. RSP: 002b:00007f39f37eac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000012e80 RCX: 000000000045dd99 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000004 RBP: 000000000118bf58 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bf2c R13: 00007fff8753a28f R14: 00007f39f37eb9c0 R15: 000000000118bf2c INFO: task syz-executor.0:4417 blocked for more than 144 seconds. Not tainted 5.9.0-rc7-next-20200930-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.0 state:D stack:28472 pid: 4417 ppid: 6852 flags:0x10004004 Call Trace: context_switch kernel/sched/core.c:3777 [inline] __schedule+0xec5/0x2200 kernel/sched/core.c:4526 schedule+0xcf/0x270 kernel/sched/core.c:4604 schedule_timeout+0x1d8/0x250 kernel/time/timer.c:1855 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:2832 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+0x2a7/0x7f0 block/ioctl.c:623 block_ioctl+0xf9/0x140 fs/block_dev.c:1866 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: 0033:0x45dd99 Code: Bad RIP value. RSP: 002b:00007f39f37eac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000012e80 RCX: 000000000045dd99 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000004 RBP: 000000000118bf58 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bf2c R13: 00007fff8753a28f R14: 00007f39f37eb9c0 R15: 000000000118bf2c Showing all locks held in the system: 1 lock held by khungtaskd/1178: #0: ffffffff8a553d00 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6221 1 lock held by in:imklog/6557: #0: ffff8880a0a526b0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:930 2 locks held by kworker/u5:2/6867: #0: ffff888093c7f138 ((wq_completion)knbd0-recv){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff888093c7f138 ((wq_completion)knbd0-recv){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline] #0: ffff888093c7f138 ((wq_completion)knbd0-recv){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline] #0: ffff888093c7f138 ((wq_completion)knbd0-recv){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline] #0: ffff888093c7f138 ((wq_completion)knbd0-recv){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #0: ffff888093c7f138 ((wq_completion)knbd0-recv){+.+.}-{0:0}, at: process_one_work+0x821/0x15a0 kernel/workqueue.c:2240 #1: ffffc900017b7da8 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x854/0x15a0 kernel/workqueue.c:2244 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1178 Comm: khungtaskd Not tainted 5.9.0-rc7-next-20200930-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+0x198/0x1fb 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:339 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: 6835 Comm: syz-fuzzer Not tainted 5.9.0-rc7-next-20200930-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0033:0x415b7a Code: 89 ac 24 c8 00 00 00 48 8d ac 24 c8 00 00 00 48 8b 94 24 e0 00 00 00 48 83 fa 08 0f 84 4d 09 00 00 48 8b 1d 98 4a 5a 01 84 03 <90> 48 8b b4 24 d8 00 00 00 48 bf 00 00 00 00 00 80 00 00 48 8d 04 RSP: 002b:000000c026e52b98 EFLAGS: 00000246 RAX: 000000c026e52c18 RBX: 00007f1f2ef8f000 RCX: 000000c000083980 RDX: 0000000000000030 RSI: 0000000000000000 RDI: 0000000000000030 RBP: 000000c026e52c60 R08: 00000000008f7880 R09: 0000000000203000 R10: 000000c011bb4cf0 R11: 0000000000000001 R12: ffffffffffffffff R13: 0000000000000046 R14: 0000000000000045 R15: 00000000000000aa FS: 0000000001992df0 GS: 0000000000000000