INFO: task syz-executor0:8006 blocked for more than 120 seconds. Not tainted 4.15.0-rc2+ #206 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor0 D25296 8006 3328 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 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3492 __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: 0033:0x4529d9 RSP: 002b:00007fd0c29cfc58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000758020 RCX: 00000000004529d9 RDX: 0000000000000015 RSI: 0000000000004c06 RDI: 0000000000000015 RBP: 000000000000015d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006ef158 R13: 00000000ffffffff R14: 00007fd0c29d06d4 R15: 0000000000000000 Showing all locks held in the system: 2 locks held by khungtaskd/675: #0: (rcu_read_lock){....}, at: [<000000009e4804aa>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<000000009e4804aa>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.?.+}, at: [<000000004050e279>] debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4554 1 lock held by rsyslogd/2981: #0: (&f->f_pos_lock){+.+.}, at: [<000000004f169487>] __fdget_pos+0x131/0x1a0 fs/file.c:770 2 locks held by getty/3063: #0: (&tty->ldisc_sem){++++}, at: [<000000004a2749a1>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<000000004e348b37>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3064: #0: (&tty->ldisc_sem){++++}, at: [<000000004a2749a1>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<000000004e348b37>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3065: #0: (&tty->ldisc_sem){++++}, at: [<000000004a2749a1>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<000000004e348b37>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3066: #0: (&tty->ldisc_sem){++++}, at: [<000000004a2749a1>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<000000004e348b37>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3067: #0: (&tty->ldisc_sem){++++}, at: [<000000004a2749a1>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<000000004e348b37>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3068: #0: (&tty->ldisc_sem){++++}, at: [<000000004a2749a1>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<000000004e348b37>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3069: #0: (&tty->ldisc_sem){++++}, at: [<000000004a2749a1>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<000000004e348b37>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 1 lock held by syz-executor0/8006: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000729dee4c>] lo_ioctl+0x8b/0x1b90 drivers/block/loop.c:1355 1 lock held by syz-executor0/8025: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000729dee4c>] lo_ioctl+0x8b/0x1b90 drivers/block/loop.c:1355 1 lock held by syz-executor0/8031: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000729dee4c>] lo_ioctl+0x8b/0x1b90 drivers/block/loop.c:1355 1 lock held by syz-executor0/8050: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000729dee4c>] lo_ioctl+0x8b/0x1b90 drivers/block/loop.c:1355 1 lock held by syz-executor7/8011: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000729dee4c>] lo_ioctl+0x8b/0x1b90 drivers/block/loop.c:1355 1 lock held by syz-executor7/8021: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000729dee4c>] lo_ioctl+0x8b/0x1b90 drivers/block/loop.c:1355 1 lock held by syz-executor7/8029: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000729dee4c>] lo_ioctl+0x8b/0x1b90 drivers/block/loop.c:1355 1 lock held by syz-executor7/8045: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000729dee4c>] lo_ioctl+0x8b/0x1b90 drivers/block/loop.c:1355 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 675 Comm: khungtaskd Not tainted 4.15.0-rc2+ #206 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:441 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-rc2+ #206 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: 00000000fde17d2a task.stack: 00000000e3b05d87 RIP: 0010:idle_cpu kernel/sched/core.c:3913 [inline] RIP: 0010:got_nohz_idle_kick kernel/sched/core.c:614 [inline] RIP: 0010:scheduler_ipi+0x378/0x830 kernel/sched/core.c:1777 RSP: 0018:ffff8801db407d70 EFLAGS: 00000046 RAX: ffff8801db400000 RBX: 0000000000025a80 RCX: 0000000000000000 RDX: ffffffff85be9ae0 RSI: 0000000000000000 RDI: ffff8801db425ac0 RBP: ffff8801db407e90 R08: 1ffff1003b684c8e R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801db425a80 R13: 1ffff1003b680fb1 R14: ffff8801db407e68 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8801db400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000ddc000 CR3: 00000001cbdac000 CR4: 00000000001406f0 DR0: 0000000020000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: smp_reschedule_interrupt+0xe6/0x670 arch/x86/kernel/smp.c:277 reschedule_interrupt+0x9d/0xb0 arch/x86/entry/entry_64.S:819 RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54 RSP: 0018:ffffffff85e07d08 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff02 RAX: dffffc0000000000 RBX: 1ffffffff0bc0fa4 RCX: 0000000000000000 RDX: 1ffffffff0bd968c RSI: 0000000000000001 RDI: ffffffff85ecb460 RBP: ffffffff85e07d08 R08: ffffffff85be9ae0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffffffff85e07dc0 R14: ffffffff865ea860 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:93 [inline] default_idle+0xbf/0x460 arch/x86/kernel/process.c:348 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:339 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 rest_init+0xed/0xf0 init/main.c:435 start_kernel+0x729/0x74f init/main.c:710 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: 80 f9 03 7f 21 48 89 95 e8 fe ff ff 48 89 85 f0 fe ff ff e8 db e0 59 00 48 8b 95 e8 fe ff ff 48 8b 85 f0 fe ff ff 41 8b 74 24 40 <85> f6 0f 85 76 fe ff ff 49 8d 46 80 49 8d bc 24 a0 0b 00 00 48