INFO: task syz-executor7:16224 blocked for more than 120 seconds. Not tainted 4.15.0-rc8+ #263 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor7 D23400 16224 5965 0x00000004 Call Trace: context_switch kernel/sched/core.c:2799 [inline] __schedule+0x8eb/0x2060 kernel/sched/core.c:3375 schedule+0xf5/0x430 kernel/sched/core.c:3434 blk_mq_freeze_queue_wait+0x1bb/0x400 block/blk-mq.c:137 blk_freeze_queue+0x4a/0x80 block/blk-mq.c:166 blk_mq_freeze_queue+0x15/0x20 block/blk-mq.c:175 loop_set_status+0x1a2/0xf60 drivers/block/loop.c:1097 loop_set_status64+0x9d/0x110 drivers/block/loop.c:1271 lo_ioctl+0xd86/0x1b70 drivers/block/loop.c:1381 __blkdev_driver_ioctl block/ioctl.c:303 [inline] blkdev_ioctl+0x1759/0x1e00 block/ioctl.c:601 block_ioctl+0xde/0x120 fs/block_dev.c:1860 vfs_ioctl fs/ioctl.c:46 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 entry_SYSCALL_64_fastpath+0x29/0xa0 RIP: 0033:0x452df9 RSP: 002b:00007f8a94648c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f8a94649700 RCX: 0000000000452df9 RDX: 000000002001df4c RSI: 0000000000004c04 RDI: 0000000000000013 RBP: 0000000000a2f870 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000212 R12: 0000000000000000 R13: 0000000000a2f7ef R14: 00007f8a946499c0 R15: 0000000000000002 Showing all locks held in the system: 2 locks held by khungtaskd/748: #0: (rcu_read_lock){....}, at: [<0000000064975896>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<0000000064975896>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<00000000d40aab70>] debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4464 2 locks held by getty/3658: #0: (&tty->ldisc_sem){++++}, at: [<00000000d3953023>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000ed588dab>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3659: #0: (&tty->ldisc_sem){++++}, at: [<00000000d3953023>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000ed588dab>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3660: #0: (&tty->ldisc_sem){++++}, at: [<00000000d3953023>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000ed588dab>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3661: #0: (&tty->ldisc_sem){++++}, at: [<00000000d3953023>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000ed588dab>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3662: #0: (&tty->ldisc_sem){++++}, at: [<00000000d3953023>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000ed588dab>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3663: #0: (&tty->ldisc_sem){++++}, at: [<00000000d3953023>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000ed588dab>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3664: #0: (&tty->ldisc_sem){++++}, at: [<00000000d3953023>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000ed588dab>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 1 lock held by syz-executor7/16224: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000b5f13fe1>] lo_ioctl+0x8b/0x1b70 drivers/block/loop.c:1355 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 748 Comm: khungtaskd Not tainted 4.15.0-rc8+ #263 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x122/0x180 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:138 [inline] check_hung_task kernel/hung_task.c:132 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline] watchdog+0x90c/0xd60 kernel/hung_task.c:249 kthread+0x33c/0x400 kernel/kthread.c:238 ret_from_fork+0x37/0x50 arch/x86/entry/entry_64.S:530 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.15.0-rc8+ #263 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:irq_work_needs_cpu+0xdd/0x280 kernel/irq_work.c:122 RSP: 0018:ffff8801db207aa0 EFLAGS: 00000046 RAX: 0000000000000000 RBX: 1ffff1003b640f55 RCX: 1ffff1003b640f59 RDX: dffffc0000000000 RSI: ffff8801db207c48 RDI: ffffffff86944858 RBP: ffff8801db207b70 R08: ffffffff8163ca4e R09: 1ffff1003b640f50 R10: ffff8801db207a50 R11: 0000000000000000 R12: 1ffff1003b640f59 R13: ffff8801db207b48 R14: ffff8801db227b40 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000266e000 CR3: 0000000006822001 CR4: 00000000001606f0 Call Trace: tick_nohz_stop_sched_tick kernel/time/tick-sched.c:685 [inline] __tick_nohz_idle_enter+0xb60/0x1640 kernel/time/tick-sched.c:926 tick_nohz_irq_exit+0x4e/0x60 kernel/time/tick-sched.c:986 tick_irq_exit kernel/softirq.c:387 [inline] irq_exit+0x1b6/0x200 kernel/softirq.c:407 scheduler_ipi+0x318/0x820 kernel/sched/core.c:1803 smp_reschedule_interrupt+0xe6/0x670 arch/x86/kernel/smp.c:277 reschedule_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:950 RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54 RSP: 0018:ffffffff86807c38 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff02 RAX: dffffc0000000000 RBX: 1ffffffff0d00f8a RCX: 0000000000000000 RDX: 1ffffffff0d19178 RSI: 0000000000000001 RDI: ffffffff868c8bc0 RBP: ffffffff86807c38 R08: ffffffff8666fae0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffffffff86807cf0 R14: ffffffff87037da0 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:93 [inline] default_idle+0xbf/0x460 arch/x86/kernel/process.c:355 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:346 default_idle_call+0x36/0x90 kernel/sched/idle.c:98 cpuidle_idle_call kernel/sched/idle.c:156 [inline] do_idle+0x24a/0x3b0 kernel/sched/idle.c:246 cpu_startup_entry+0x104/0x120 kernel/sched/idle.c:351 rest_init+0xed/0xf0 init/main.c:436 start_kernel+0x7f1/0x819 init/main.c:716 x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:378 x86_64_start_kernel+0x77/0x7a arch/x86/kernel/head64.c:359 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:237 Code: ba 00 00 00 00 00 fc ff df 4c 89 e1 48 c1 e9 03 80 3c 11 00 0f 85 82 01 00 00 49 c1 ec 03 49 bf 00 00 00 00 00 fc ff df 48 85 c0 <49> 89 45 80 43 c6 04 3c f8 74 62 e8 73 2b f4 ff 48 c7 c0 54 65