ptrace attach of "/root/syz-executor1"[4612] was attempted by "/root/syz-executor1"[16968] ptrace attach of "/root/syz-executor1"[4612] was attempted by "/root/syz-executor1"[16966] INFO: task syz-executor2:16936 blocked for more than 120 seconds. Not tainted 4.17.0-rc3+ #32 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor2 D25304 16936 4610 0x00000004 Call Trace: context_switch kernel/sched/core.c:2848 [inline] __schedule+0x801/0x1e30 kernel/sched/core.c:3490 schedule+0xef/0x430 kernel/sched/core.c:3549 blk_mq_freeze_queue_wait+0x1ce/0x460 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+0x1ff/0x1010 drivers/block/loop.c:1119 loop_set_status64+0xaa/0x100 drivers/block/loop.c:1305 lo_ioctl+0x6f5/0x2130 drivers/block/loop.c:1421 __blkdev_driver_ioctl block/ioctl.c:303 [inline] blkdev_ioctl+0x9b6/0x2020 block/ioctl.c:601 block_ioctl+0xee/0x130 fs/block_dev.c:1877 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x1cf/0x16a0 fs/ioctl.c:684 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701 __do_sys_ioctl fs/ioctl.c:708 [inline] __se_sys_ioctl fs/ioctl.c:706 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:706 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x455979 RSP: 002b:00007f05b0aefc68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f05b0af06d4 RCX: 0000000000455979 RDX: 00000000200002c0 RSI: 0000000000004c04 RDI: 0000000000000014 RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000002b4 R14: 00000000006f8180 R15: 0000000000000000 Showing all locks held in the system: 2 locks held by khungtaskd/892: #0: 000000009f6fca2a (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: 000000009f6fca2a (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249 #1: 00000000b7e0de99 (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470 2 locks held by getty/4532: #0: 00000000b1b2ad7c (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000076643abf (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4533: #0: 000000008f8b5530 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000430643ed (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4534: #0: 000000007c68a415 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000b4666d33 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4535: #0: 0000000086a3cdaf (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000001befcb73 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4536: #0: 00000000de040d33 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000003fa63ca9 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4537: #0: 00000000709b6539 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000006bdeddf4 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4538: #0: 0000000042be887d (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000944fbdbd (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 1 lock held by syz-executor0/4607: #0: 00000000cbc55dff (&lo->lo_ctl_mutex/1){+.+.}, at: lo_ioctl+0x8d/0x2130 drivers/block/loop.c:1391 1 lock held by syz-executor2/16936: #0: 00000000cbc55dff (&lo->lo_ctl_mutex/1){+.+.}, at: lo_ioctl+0x8d/0x2130 drivers/block/loop.c:1391 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 892 Comm: khungtaskd Not tainted 4.17.0-rc3+ #32 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:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54