INFO: task syz-executor3:12157 blocked for more than 120 seconds. Not tainted 4.15.0-rc2-next-20171208+ #63 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor3 D25536 12157 3362 0x00000004 Call Trace: context_switch kernel/sched/core.c:2800 [inline] __schedule+0x8eb/0x2060 kernel/sched/core.c:3376 schedule+0xf5/0x430 kernel/sched/core.c:3435 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3493 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xaad/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 lo_ioctl+0x8b/0x1b90 drivers/block/loop.c:1355 __blkdev_driver_ioctl block/ioctl.c:303 [inline] blkdev_ioctl+0x1759/0x1e00 block/ioctl.c:601 block_ioctl+0xea/0x130 fs/block_dev.c:1860 vfs_ioctl fs/ioctl.c:46 [inline] do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:686 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 entry_SYSCALL_64_fastpath+0x1f/0x96 RIP: 0033:0x452a39 RSP: 002b:00007fd85b57ec58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000758190 RCX: 0000000000452a39 RDX: 0000000020e67fd8 RSI: 00000000400454ca RDI: 0000000000000016 RBP: 000000000000005b R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006ee928 R13: 00000000ffffffff R14: 00007fd85b57f6d4 R15: 0000000000000002 Showing all locks held in the system: 2 locks held by khungtaskd/671: #0: (rcu_read_lock){....}, at: [<0000000053bc3983>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<0000000053bc3983>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<00000000c2c6381b>] debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4554 2 locks held by getty/3115: #0: (&tty->ldisc_sem){++++}, at: [<00000000e7f92d1f>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000f15a7c4f>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3116: #0: (&tty->ldisc_sem){++++}, at: [<00000000e7f92d1f>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000f15a7c4f>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3117: #0: (&tty->ldisc_sem){++++}, at: [<00000000e7f92d1f>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000f15a7c4f>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3118: #0: (&tty->ldisc_sem){++++}, at: [<00000000e7f92d1f>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000f15a7c4f>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3119: #0: (&tty->ldisc_sem){++++}, at: [<00000000e7f92d1f>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000f15a7c4f>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3120: #0: (&tty->ldisc_sem){++++}, at: [<00000000e7f92d1f>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000f15a7c4f>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 1 lock held by syz-executor3/12157: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000d5130113>] lo_ioctl+0x8b/0x1b90 drivers/block/loop.c:1355 1 lock held by syz-executor7/12154: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000d5130113>] lo_ioctl+0x8b/0x1b90 drivers/block/loop.c:1355 1 lock held by syz-executor7/12168: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000d5130113>] lo_ioctl+0x8b/0x1b90 drivers/block/loop.c:1355 1 lock held by syz-executor5/12216: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000d5130113>] lo_ioctl+0x8b/0x1b90 drivers/block/loop.c:1355 2 locks held by getty/12231: #0: (&tty->ldisc_sem){++++}, at: [<00000000e7f92d1f>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000f15a7c4f>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 1 lock held by blkid/12232: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000d5130113>] lo_ioctl+0x8b/0x1b90 drivers/block/loop.c:1355 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 671 Comm: khungtaskd Not tainted 4.15.0-rc2-next-20171208+ #63 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+0x37a/0x440 kernel/kthread.c:238 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:524 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-rc2-next-20171208+ #63 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:unwind_next_frame.part.6+0x5f1/0xb40 include/linux/compiler.h:183 RSP: 0018:ffff8801db306e28 EFLAGS: 00000806 RAX: dffffc0000000000 RBX: ffff8801db306f48 RCX: ffff8801db306ef8 RDX: ffff8801db306f70 RSI: 1ffff1003b660dcf RDI: ffff8801d9f97f48 RBP: ffff8801db306f20 R08: ffff8801db306f80 R09: ffff8801d9f88300 R10: 000000000000000b R11: ffffed003b660df3 R12: 1ffff1003b660dcb R13: ffff8801db307490 R14: 1ffff1003b660dcf R15: ffff8801db306f98 FS: 0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000001e5e000 CR3: 00000001cb1b5000 CR4: 00000000001406e0 DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 Call Trace: unwind_next_frame+0x3e/0x50 arch/x86/kernel/unwind_frame.c:287 __save_stack_trace+0x6e/0xd0 arch/x86/kernel/stacktrace.c:44 save_stack_trace+0x1a/0x20 arch/x86/kernel/stacktrace.c:60 add_xhlock kernel/locking/lockdep.c:4880 [inline] check_add_xhlock kernel/locking/lockdep.c:4907 [inline] lock_acquire_crosslock kernel/locking/lockdep.c:4979 [inline] __lock_acquire+0x324e/0x47f0 kernel/locking/lockdep.c:3503 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4004 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:159 rq_lock_irqsave kernel/sched/sched.h:1750 [inline] update_blocked_averages+0x124/0x1b60 kernel/sched/fair.c:7353 rebalance_domains+0x145/0xcc0 kernel/sched/fair.c:9122 run_rebalance_domains+0x381/0x780 kernel/sched/fair.c:9383 __do_softirq+0x29d/0xbb2 kernel/softirq.c:285 invoke_softirq kernel/softirq.c:365 [inline] irq_exit+0x1d3/0x210 kernel/softirq.c:405 scheduler_ipi+0x32a/0x830 kernel/sched/core.c:1804 smp_reschedule_interrupt+0xe6/0x670 arch/x86/kernel/smp.c:277 reschedule_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:944 RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54 RSP: 0018:ffff8801d9f97da8 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff02 RAX: dffffc0000000000 RBX: 1ffff1003b3f2fb8 RCX: 0000000000000000 RDX: 1ffffffff0c5975c RSI: 0000000000000001 RDI: ffffffff862cbae0 RBP: ffff8801d9f97da8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 R13: ffff8801d9f97e60 R14: ffffffff869efaa0 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:93 [inline] default_idle+0xbf/0x430 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+0x18/0x20 kernel/sched/idle.c:351 start_secondary+0x330/0x460 arch/x86/kernel/smpboot.c:277 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:237 Code: 8b 6d 00 4c 89 f6 48 c1 ee 03 80 3c 06 00 0f 85 e9 04 00 00 49 c1 ee 03 48 b8 00 00 00 00 00 fc ff df 4c 89 69 80 41 c6 04 06 f8 97 fb ff ff 80 3d f7 60 6e 05 00 0f 85 fc fc ff ff 49 8d be