INFO: task syz-executor5:11397 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-executor5 D23472 11397 4237 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_change_fd drivers/block/loop.c:667 [inline] lo_ioctl+0x10ce/0x1b70 drivers/block/loop.c:1361 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: 0023:0xf7fc8c79 RSP: 002b:00000000f77c408c EFLAGS: 00000296 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 0000000000000013 RCX: 0000000000004c06 RDX: 0000000000000013 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: [<00000000d780bd29>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<00000000d780bd29>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<00000000b704e4ee>] debug_show_all_locks+0xd3/0x3d0 kernel/locking/lockdep.c:4470 1 lock held by rsyslogd/4030: #0: (&f->f_pos_lock){+.+.}, at: [<000000005f151bb8>] __fdget_pos+0x12b/0x190 fs/file.c:765 2 locks held by getty/4153: #0: (&tty->ldisc_sem){++++}, at: [<000000008de4cf45>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000060945ae2>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4154: #0: (&tty->ldisc_sem){++++}, at: [<000000008de4cf45>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000060945ae2>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4155: #0: (&tty->ldisc_sem){++++}, at: [<000000008de4cf45>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000060945ae2>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4156: #0: (&tty->ldisc_sem){++++}, at: [<000000008de4cf45>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000060945ae2>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4157: #0: (&tty->ldisc_sem){++++}, at: [<000000008de4cf45>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000060945ae2>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4158: #0: (&tty->ldisc_sem){++++}, at: [<000000008de4cf45>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000060945ae2>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 1 lock held by syz-executor5/11397: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000d86a1774>] lo_ioctl+0x8b/0x1b70 drivers/block/loop.c:1355 2 locks held by getty/11446: #0: (&tty->ldisc_sem){++++}, at: [<000000008de4cf45>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000060945ae2>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 1 lock held by blkid/11447: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000d86a1774>] 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: 0 Comm: swapper/1 Not tainted 4.15.0+ #208 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__local_bh_disable_ip+0x0/0x120 arch/x86/include/asm/paravirt.h:782 RSP: 0018:ffff8801db507d50 EFLAGS: 00000046 RAX: 0000000080000001 RBX: ffff8801d9f10300 RCX: 1ffff1003b6a46e9 RDX: 0000000000000000 RSI: 0000000000000200 RDI: ffffffff8142fc50 RBP: ffff8801db507d60 R08: 1ffff1003b6a59f5 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801d9f10300 R13: 1ffff1003b6a0fb1 R14: ffff8801db507e68 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff8801db500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000d97000 CR3: 0000000006a22002 CR4: 00000000001606e0 Call Trace: scheduler_ipi+0x23d/0x820 kernel/sched/core.c:1794 smp_reschedule_interrupt+0xe6/0x670 arch/x86/kernel/smp.c:277 reschedule_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:849 RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54 RSP: 0018:ffff8801d9f1fcb0 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff02 RAX: dffffc0000000000 RBX: 1ffff1003b3e3f99 RCX: 0000000000000000 RDX: 1ffffffff0d59278 RSI: 0000000000000001 RDI: ffffffff86ac93c0 RBP: ffff8801d9f1fcb0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 R13: ffff8801d9f1fd68 R14: ffffffff87268da0 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:93 [inline] default_idle+0xbf/0x430 arch/x86/kernel/process.c:354 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:345 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:267 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:237 Code: ff ff e8 a4 1d 66 00 e9 7b ff ff ff e8 ba 1d 66 00 e9 28 ff ff ff e8 b0 1d 66 00 e9 a1 fe ff ff 90 66 2e 0f 1f 84 00 00 00 00 00 <55> 48 89 e5 41 54 53 49 89 fc 48 83 ec 08 65 8b 05 eb 13 bf 7e