INFO: task syz-executor3:11022 blocked for more than 120 seconds. Not tainted 4.15.0-rc9+ #277 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor3 D25648 11022 3719 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: 0033:0x452f19 RSP: 002b:00007f86a6862c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452f19 RDX: 0000000020ba0000 RSI: 0000000000004c04 RDI: 0000000000000014 RBP: 000000000000061c R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f8340 R13: 00000000ffffffff R14: 00007f86a68636d4 R15: 0000000000000000 Showing all locks held in the system: 2 locks held by khungtaskd/746: #0: (rcu_read_lock){....}, at: [<0000000039ca5d7a>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<0000000039ca5d7a>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<00000000f0d0bcd3>] debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4464 2 locks held by getty/3638: #0: (&tty->ldisc_sem){++++}, at: [<0000000000b6335e>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000ea3023a3>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3639: #0: (&tty->ldisc_sem){++++}, at: [<0000000000b6335e>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000ea3023a3>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3640: #0: (&tty->ldisc_sem){++++}, at: [<0000000000b6335e>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000ea3023a3>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3641: #0: (&tty->ldisc_sem){++++}, at: [<0000000000b6335e>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000ea3023a3>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3642: #0: (&tty->ldisc_sem){++++}, at: [<0000000000b6335e>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000ea3023a3>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3643: #0: (&tty->ldisc_sem){++++}, at: [<0000000000b6335e>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000ea3023a3>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3644: #0: (&tty->ldisc_sem){++++}, at: [<0000000000b6335e>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000ea3023a3>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 1 lock held by syz-executor3/11022: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<0000000074d76ade>] lo_ioctl+0x8b/0x1b70 drivers/block/loop.c:1355 1 lock held by syz-executor3/11031: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<0000000074d76ade>] lo_ioctl+0x8b/0x1b70 drivers/block/loop.c:1355 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 746 Comm: khungtaskd Not tainted 4.15.0-rc9+ #277 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+0x3a/0x50 arch/x86/entry/entry_64.S:541 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.15.0-rc9+ #277 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__lock_acquire+0xf5/0x3e00 kernel/locking/lockdep.c:3285 RSP: 0018:ffff8801db3076a0 EFLAGS: 00000086 RAX: ffffed003b660ee8 RBX: 0000000000000001 RCX: 0000000000000002 RDX: dffffc0000000000 RSI: 0000000000000000 RDI: ffffffff8680da08 RBP: ffff8801db307a30 R08: ffffffff8163dafe R09: 0000000000000001 R10: 0000000000000000 R11: ffffffff8680da08 R12: 1ffff1003b660f54 R13: 0000000000000000 R14: 0000000000000002 R15: ffff8801d9f66300 FS: 0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c433de6888 CR3: 0000000006822005 CR4: 00000000001606e0 Call Trace: lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3914 seqcount_lockdep_reader_access include/linux/seqlock.h:81 [inline] read_seqcount_begin include/linux/seqlock.h:164 [inline] read_seqbegin include/linux/seqlock.h:434 [inline] tick_nohz_stop_sched_tick kernel/time/tick-sched.c:668 [inline] __tick_nohz_idle_enter+0x2c4/0x1640 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:961 RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54 RSP: 0018:ffff8801d9f77cb0 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff02 RAX: dffffc0000000000 RBX: 1ffff1003b3eef99 RCX: 0000000000000000 RDX: 1ffffffff0d19190 RSI: 0000000000000001 RDI: ffffffff868c8c80 RBP: ffff8801d9f77cb0 R08: ffffffff86670ae8 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 R13: ffff8801d9f77d68 R14: ffffffff870386e0 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 start_secondary+0x40a/0x590 arch/x86/kernel/smpboot.c:268 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:237 Code: f2 c7 40 20 f2 f2 f2 f2 c7 40 24 00 f2 f2 f2 c7 40 28 f2 f2 f2 f2 c7 40 2c 00 f2 f2 f2 c7 40 30 f2 f2 f2 f2 c7 40 34 00 f2 f2 f2 40 38 f2 f2 f2 f2 c7 40 3c 00 f2 f2 f2 c7 40 40 f2 f2 f2 f2