INFO: task syz-executor7:20685 blocked for more than 120 seconds. Not tainted 4.17.0-rc7+ #106 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor7 D25128 20685 4590 0x20020004 Call Trace: context_switch kernel/sched/core.c:2876 [inline] __schedule+0x801/0x1e30 kernel/sched/core.c:3518 schedule+0xef/0x430 kernel/sched/core.c:3562 blk_mq_freeze_queue_wait+0x1ce/0x460 block/blk-mq.c:152 blk_freeze_queue+0x4a/0x80 block/blk-mq.c:181 blk_mq_freeze_queue+0x15/0x20 block/blk-mq.c:190 loop_change_fd drivers/block/loop.c:689 [inline] lo_ioctl+0xa9a/0x2130 drivers/block/loop.c:1401 lo_compat_ioctl+0xc1/0x170 drivers/block/loop.c:1603 compat_blkdev_ioctl+0x3c2/0x1b20 block/compat_ioctl.c:406 __do_compat_sys_ioctl fs/compat_ioctl.c:1461 [inline] __se_compat_sys_ioctl fs/compat_ioctl.c:1407 [inline] __ia32_compat_sys_ioctl+0x221/0x640 fs/compat_ioctl.c:1407 do_syscall_32_irqs_on arch/x86/entry/common.c:323 [inline] do_fast_syscall_32+0x345/0xf9b arch/x86/entry/common.c:394 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 RIP: 0023:0xf7faecb9 RSP: 002b:00000000f5f680ac EFLAGS: 00000282 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 0000000000000015 RCX: 0000000000004c06 RDX: 0000000000000015 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Showing all locks held in the system: 2 locks held by khungtaskd/894: #0: 00000000e4f4ea69 (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: 00000000e4f4ea69 (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249 #1: 00000000037140c3 (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470 2 locks held by getty/4513: #0: 000000005ef36fa9 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000cac10262 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4514: #0: 000000007fcc52ae (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000a0317ec4 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4515: #0: 000000003534acc3 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000006a74562c (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4516: #0: 0000000051fba12a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000954465a9 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4517: #0: 0000000039d71d4d (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000021d23e7e (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4518: #0: 000000004e1dfb2c (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000be393490 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4519: #0: 00000000bae2c332 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000000befbca5 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 1 lock held by syz-executor7/20685: #0: 000000007b5853d1 (&lo->lo_ctl_mutex/1){+.+.}, at: lo_ioctl+0x8d/0x2130 drivers/block/loop.c:1392 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 894 Comm: khungtaskd Not tainted 4.17.0-rc7+ #106 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1b9/0x294 lib/dump_stack.c:113 nmi_cpu_backtrace.cold.4+0x19/0xce lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x151/0x192 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+0xc10/0xf60 kernel/hung_task.c:249 kthread+0x345/0x410 kernel/kthread.c:240 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54