INFO: task syz-executor.3:18923 blocked for more than 143 seconds. Not tainted 5.5.0-rc3-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D27840 18923 9129 0x00004004 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x934/0x1f90 kernel/sched/core.c:4081 schedule+0xdc/0x2b0 kernel/sched/core.c:4155 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+0x40a/0x14c0 kernel/workqueue.c:2827 nbd_start_device_ioctl drivers/block/nbd.c:1301 [inline] __nbd_ioctl drivers/block/nbd.c:1376 [inline] nbd_ioctl+0x817/0xc4b drivers/block/nbd.c:1416 __blkdev_driver_ioctl block/ioctl.c:277 [inline] blkdev_ioctl+0x1302/0x1df0 block/ioctl.c:582 block_ioctl+0xee/0x130 fs/block_dev.c:1983 vfs_ioctl fs/ioctl.c:47 [inline] file_ioctl fs/ioctl.c:545 [inline] do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732 ksys_ioctl+0xab/0xd0 fs/ioctl.c:749 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45a919 Code: 48 01 de 48 29 d9 e8 56 f8 ff ff 48 8b ac 24 00 80 00 00 48 81 c4 08 80 00 00 c3 e8 41 f6 ff ff e9 4c ff ff ff 48 8d bc 24 10 <80> 00 00 48 39 3b 75 8c 48 89 23 eb 87 cc cc cc cc cc cc cc cc cc RSP: 002b:00007ff9f8b48c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 000000000045a919 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000006 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff9f8b496d4 R13: 00000000004c4646 R14: 00000000004d9e30 R15: 00000000ffffffff Showing all locks held in the system: 1 lock held by khungtaskd/1114: #0: ffffffff899a5680 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279 kernel/locking/lockdep.c:5334 2 locks held by getty/9081: #0: ffff8880a6ada090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000177b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9082: #0: ffff88808c53b090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900017db2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9083: #0: ffff888094bc5090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900017fb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9084: #0: ffff8880a4a84090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000179b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9085: #0: ffff888093484090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900017ab2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9086: #0: ffff8880a45d7090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900017eb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9087: #0: ffff888215680090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900011402e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by kworker/u5:1/9520: #0: ffff888054b6ed28 ((wq_completion)knbd3-recv){+.+.}, at: __write_once_size include/linux/compiler.h:226 [inline] #0: ffff888054b6ed28 ((wq_completion)knbd3-recv){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff888054b6ed28 ((wq_completion)knbd3-recv){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:855 [inline] #0: ffff888054b6ed28 ((wq_completion)knbd3-recv){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:40 [inline] #0: ffff888054b6ed28 ((wq_completion)knbd3-recv){+.+.}, at: set_work_data kernel/workqueue.c:615 [inline] #0: ffff888054b6ed28 ((wq_completion)knbd3-recv){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:642 [inline] #0: ffff888054b6ed28 ((wq_completion)knbd3-recv){+.+.}, at: process_one_work+0x88b/0x1740 kernel/workqueue.c:2235 #1: ffffc900015d7dc0 ((work_completion)(&args->work)){+.+.}, at: process_one_work+0x8c1/0x1740 kernel/workqueue.c:2239 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1114 Comm: khungtaskd Not tainted 5.5.0-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+0x197/0x210 lib/dump_stack.c:118 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+0xb11/0x10c0 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 CPU: 0 PID: 28874 Comm: kworker/0:0 Not tainted 5.5.0-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:hlock_class kernel/locking/lockdep.c:158 [inline] RIP: 0010:lookup_chain_cache_add kernel/locking/lockdep.c:2880 [inline] RIP: 0010:validate_chain kernel/locking/lockdep.c:2936 [inline] RIP: 0010:__lock_acquire+0x16d1/0x4a00 kernel/locking/lockdep.c:3955 Code: 70 ff ff ff e8 80 22 58 00 4c 8b 9d 30 ff ff ff 4c 8b 95 70 ff ff ff 41 0f b7 5a 20 4c 89 9d 30 ff ff ff 4c 89 95 70 ff ff ff <66> 81 e3 ff 1f 0f b7 db be 08 00 00 00 48 89 d8 48 c1 f8 06 48 8d RSP: 0018:ffffc900018275f0 EFLAGS: 00000046 RAX: 0000000000000000 RBX: 000000000000001d RCX: ffffffff815ab620 RDX: 1ffff11014d639d3 RSI: 0000000000000008 RDI: ffffffff8b2cf5b0 RBP: ffffc90001827708 R08: 1ffffffff1659bac R09: fffffbfff1659bad R10: ffff8880a6b1ce78 R11: ffff8880a6b1c540 R12: 0000000033cc5735 R13: ffffffff8a79cad0 R14: ffff8880a6b1ce50 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f36fefec000 CR3: 0000000095ef9000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4485 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:159 rmqueue mm/page_alloc.c:3284 [inline] get_page_from_freelist+0x7d2/0x4290 mm/page_alloc.c:3692 __alloc_pages_nodemask+0x2d0/0x910 mm/page_alloc.c:4756 __alloc_pages include/linux/gfp.h:496 [inline] __alloc_pages_node include/linux/gfp.h:509 [inline] kmem_getpages mm/slab.c:1367 [inline] cache_grow_begin+0x90/0xc60 mm/slab.c:2600 cache_alloc_refill mm/slab.c:2972 [inline] ____cache_alloc mm/slab.c:3055 [inline] ____cache_alloc mm/slab.c:3038 [inline] slab_alloc_node mm/slab.c:3250 [inline] kmem_cache_alloc_node_trace+0x689/0x750 mm/slab.c:3593 __do_kmalloc_node mm/slab.c:3615 [inline] __kmalloc_node_track_caller+0x3d/0x70 mm/slab.c:3630 __kmalloc_reserve.isra.0+0x40/0xf0 net/core/skbuff.c:141 __alloc_skb+0x10b/0x5e0 net/core/skbuff.c:209 alloc_skb include/linux/skbuff.h:1049 [inline] nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:321 [inline] nsim_dev_trap_report drivers/net/netdevsim/dev.c:373 [inline] nsim_dev_trap_report_work+0x25c/0xaf0 drivers/net/netdevsim/dev.c:412 process_one_work+0x9af/0x1740 kernel/workqueue.c:2264 worker_thread+0x98/0xe40 kernel/workqueue.c:2410 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352