INFO: task syz-executor.0:11367 blocked for more than 143 seconds. Not tainted 5.4.0-rc4+ #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D27416 11367 9523 0x00004004 Call Trace: context_switch kernel/sched/core.c:3384 [inline] __schedule+0x94f/0x1e70 kernel/sched/core.c:4069 schedule+0xd9/0x260 kernel/sched/core.c:4136 schedule_timeout+0x717/0xc50 kernel/time/timer.c:1871 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common kernel/sched/completion.c:115 [inline] wait_for_completion+0x29c/0x440 kernel/sched/completion.c:136 flush_workqueue+0x40f/0x14c0 kernel/workqueue.c:2826 nbd_start_device_ioctl drivers/block/nbd.c:1272 [inline] __nbd_ioctl drivers/block/nbd.c:1347 [inline] nbd_ioctl+0xb2e/0xc44 drivers/block/nbd.c:1387 __blkdev_driver_ioctl block/ioctl.c:304 [inline] blkdev_ioctl+0xedb/0x1c20 block/ioctl.c:606 block_ioctl+0xee/0x130 fs/block_dev.c:1954 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:509 [inline] do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696 ksys_ioctl+0xab/0xd0 fs/ioctl.c:713 __do_sys_ioctl fs/ioctl.c:720 [inline] __se_sys_ioctl fs/ioctl.c:718 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x459f39 Code: 48 89 76 48 48 8d 44 24 08 48 89 46 38 48 89 6e 68 48 8b 1b 64 48 89 1c 25 f8 ff ff ff 48 8b 63 38 52 e8 aa bb fe ff 48 c7 04 <25> 03 10 00 00 00 00 00 00 5a c3 cc cc cc cc cc cc cc cc cc cc cc RSP: 002b:00007fc787c8fc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 0000000000459f39 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000005 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fc787c906d4 R13: 00000000004c39e6 R14: 00000000004d7958 R15: 00000000ffffffff INFO: task syz-executor.0:11418 blocked for more than 143 seconds. Not tainted 5.4.0-rc4+ #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D26264 11418 9523 0x00004004 Call Trace: context_switch kernel/sched/core.c:3384 [inline] __schedule+0x94f/0x1e70 kernel/sched/core.c:4069 schedule+0xd9/0x260 kernel/sched/core.c:4136 io_schedule+0x1c/0x70 kernel/sched/core.c:5780 wait_on_page_bit_common mm/filemap.c:1175 [inline] wait_on_page_bit mm/filemap.c:1224 [inline] wait_on_page_locked include/linux/pagemap.h:527 [inline] wait_on_page_read mm/filemap.c:2768 [inline] do_read_cache_page+0xf2f/0x2140 mm/filemap.c:2811 read_cache_page+0x5e/0x70 mm/filemap.c:2895 read_mapping_page include/linux/pagemap.h:396 [inline] read_dev_sector+0x71/0x310 block/partition-generic.c:667 read_part_sector block/partitions/check.h:38 [inline] adfspart_check_ICS+0x12d/0xc90 block/partitions/acorn.c:361 check_partition+0x3bc/0x6ce block/partitions/check.c:167 rescan_partitions+0x230/0xa30 block/partition-generic.c:531 __blkdev_get+0x1213/0x1660 fs/block_dev.c:1637 blkdev_get+0x47/0x2c0 fs/block_dev.c:1707 blkdev_open+0x205/0x290 fs/block_dev.c:1846 do_dentry_open+0x4e6/0x1380 fs/open.c:797 vfs_open+0xa0/0xd0 fs/open.c:914 do_last fs/namei.c:3408 [inline] path_openat+0x10e9/0x46d0 fs/namei.c:3525 do_filp_open+0x1a1/0x280 fs/namei.c:3555 do_sys_open+0x3fe/0x5d0 fs/open.c:1097 __do_sys_open fs/open.c:1115 [inline] __se_sys_open fs/open.c:1110 [inline] __x64_sys_open+0x7e/0xc0 fs/open.c:1110 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x413cd1 Code: 89 44 24 08 e8 e0 91 04 00 48 8b 6c 24 58 48 83 c4 60 c3 bb 02 00 00 00 e9 b9 fe ff ff 31 db e9 b2 fe ff ff 48 8b 84 24 98 00 <00> 00 48 89 04 24 48 c7 44 24 08 00 00 00 00 48 8b 44 24 68 48 89 RSP: 002b:00007fc787c4d7a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 6666666666666667 RCX: 0000000000413cd1 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007fc787c4d850 RBP: 000000000075c070 R08: 000000000000000f R09: 0000000000000000 R10: 00007fc787c4e9d0 R11: 0000000000000293 R12: 00007fc787c4e6d4 R13: 00000000004c98be R14: 00000000004e1150 R15: 00000000ffffffff Showing all locks held in the system: 1 lock held by khungtaskd/1070: #0: ffffffff88fab400 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x27e kernel/locking/lockdep.c:5337 2 locks held by getty/9483: #0: ffff888098347090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f352e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/9484: #0: ffff88808a148090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f3d2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/9485: #0: ffff8880a6025090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f412e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/9486: #0: ffff8880a7a76090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f392e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/9487: #0: ffff8880a4e71090 (&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+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/9488: #0: ffff888096d54090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f452e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/9489: #0: ffff8880a0f1c090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f152e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.0/11418: #0: ffff888051844778 (&bdev->bd_mutex){+.+.}, at: __blkdev_get+0x19b/0x1660 fs/block_dev.c:1553 2 locks held by knbd0-recv/11370: #0: ffff888088b95d28 ((wq_completion)knbd0-recv){+.+.}, at: __write_once_size include/linux/compiler.h:226 [inline] #0: ffff888088b95d28 ((wq_completion)knbd0-recv){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff888088b95d28 ((wq_completion)knbd0-recv){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:855 [inline] #0: ffff888088b95d28 ((wq_completion)knbd0-recv){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:40 [inline] #0: ffff888088b95d28 ((wq_completion)knbd0-recv){+.+.}, at: set_work_data kernel/workqueue.c:620 [inline] #0: ffff888088b95d28 ((wq_completion)knbd0-recv){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:647 [inline] #0: ffff888088b95d28 ((wq_completion)knbd0-recv){+.+.}, at: process_one_work+0x88b/0x1740 kernel/workqueue.c:2240 #1: ffff88805d237d30 ((work_completion)(&args->work)){+.+.}, at: process_one_work+0x8c1/0x1740 kernel/workqueue.c:2244 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1070 Comm: khungtaskd Not tainted 5.4.0-rc4+ #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+0x172/0x1f0 lib/dump_stack.c:113 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:205 [inline] watchdog+0x9d0/0xef0 kernel/hung_task.c:289 kthread+0x361/0x430 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