INFO: task syz-executor6:27626 blocked for more than 120 seconds. Not tainted 4.15.0+ #208 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor6 D25968 27626 4218 0x20020004 Call Trace: context_switch kernel/sched/core.c:2845 [inline] __schedule+0x8eb/0x2060 kernel/sched/core.c:3421 schedule+0xf5/0x430 kernel/sched/core.c:3480 blk_mq_freeze_queue_wait+0x1bb/0x400 block/blk-mq.c:136 blk_freeze_queue+0x4a/0x80 block/blk-mq.c:165 blk_mq_freeze_queue+0x15/0x20 block/blk-mq.c:174 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 lo_compat_ioctl+0xab/0x140 drivers/block/loop.c:1556 compat_blkdev_ioctl+0x3ae/0x1840 block/compat_ioctl.c:406 C_SYSC_ioctl fs/compat_ioctl.c:1473 [inline] compat_SyS_ioctl+0x151/0x2a30 fs/compat_ioctl.c:1419 do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline] do_fast_syscall_32+0x3ee/0xfa1 arch/x86/entry/common.c:392 entry_SYSENTER_compat+0x54/0x63 arch/x86/entry/entry_64_compat.S:129 RIP: 0023:0xf7f99c79 RSP: 002b:00000000f779508c EFLAGS: 00000296 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 0000000000000013 RCX: 0000000000004c04 RDX: 0000000020672f18 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Showing all locks held in the system: 2 locks held by khungtaskd/757: #0: (rcu_read_lock){....}, at: [<0000000090faaa43>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<0000000090faaa43>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<0000000099f11f27>] debug_show_all_locks+0xd3/0x3d0 kernel/locking/lockdep.c:4470 1 lock held by rsyslogd/4018: #0: (&f->f_pos_lock){+.+.}, at: [<000000009722391c>] __fdget_pos+0x12b/0x190 fs/file.c:765 2 locks held by getty/4140: #0: (&tty->ldisc_sem){++++}, at: [<000000008e70e444>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000bbf16228>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4141: #0: (&tty->ldisc_sem){++++}, at: [<000000008e70e444>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000bbf16228>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4142: #0: (&tty->ldisc_sem){++++}, at: [<000000008e70e444>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000bbf16228>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4143: #0: (&tty->ldisc_sem){++++}, at: [<000000008e70e444>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000bbf16228>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4144: #0: (&tty->ldisc_sem){++++}, at: [<000000008e70e444>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000bbf16228>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4145: #0: (&tty->ldisc_sem){++++}, at: [<000000008e70e444>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000bbf16228>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/21521: #0: (&tty->ldisc_sem){++++}, at: [<000000008e70e444>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000bbf16228>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 1 lock held by syz-executor6/27626: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<0000000067158c90>] lo_ioctl+0x8b/0x1b70 drivers/block/loop.c:1355 1 lock held by syz-executor6/27641: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<0000000067158c90>] lo_ioctl+0x8b/0x1b70 drivers/block/loop.c:1355 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 757 Comm: khungtaskd Not tainted 4.15.0+ #208 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:429 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 20739 Comm: kworker/1:0 Not tainted 4.15.0+ #208 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events rht_deferred_worker RIP: 0010:__lock_acquire+0x14e/0x3e00 kernel/locking/lockdep.c:3299 RSP: 0018:ffff8801ac88f0d0 EFLAGS: 00000097 RAX: 0000000000000003 RBX: 0000000000000001 RCX: 0000000000000000 RDX: 0000000000000004 RSI: 0000000000000000 RDI: ffff8801ac88f940 RBP: ffff8801ac88f460 R08: ffffffff81486d51 R09: 0000000000000000 R10: 0000000000000000 R11: ffff8801ac88f940 R12: 1ffff10035911e99 R13: 0000000000000001 R14: 0000000000000000 R15: ffff8801b5b18680 FS: 0000000000000000(0000) GS:ffff8801db500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffb8e71f000 CR3: 0000000006a22001 CR4: 00000000001606e0 Call Trace: lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920 process_one_work+0xb71/0x1af0 kernel/workqueue.c:2089 worker_thread+0x223/0x1990 kernel/workqueue.c:2247 kthread+0x33c/0x400 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:429 Code: 8e cf 86 48 c1 e8 03 0f b6 14 10 48 c7 c0 60 8e cf 86 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 2b 0e 00 00 44 8b 2d e2 2f 79 05 <45> 85 ed 0f 84 4d 08 00 00 48 c7 c2 80 a2 14 88 48 b8 00 00 00