INFO: task syz-executor.0:7263 blocked for more than 140 seconds. Not tainted 4.14.138 #34 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D24992 7263 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:2807 [inline] __schedule+0x7b8/0x1cd0 kernel/sched/core.c:3383 schedule+0x92/0x1c0 kernel/sched/core.c:3427 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3485 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 fuse_lock_inode+0xbc/0xf0 fs/fuse/inode.c:365 fuse_lookup+0x7a/0x380 fs/fuse/dir.c:360 lookup_slow+0x226/0x440 fs/namei.c:1695 walk_component+0x698/0x1d00 fs/namei.c:1824 link_path_walk+0x81f/0x10a0 fs/namei.c:2153 path_mountpoint+0xac/0x1970 fs/namei.c:2717 filename_mountpoint+0x16c/0x320 fs/namei.c:2744 user_path_mountpoint_at+0x3a/0x50 fs/namei.c:2774 SYSC_umount fs/namespace.c:1730 [inline] SyS_umount+0x10c/0x380 fs/namespace.c:1714 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45c257 RSP: 002b:00007ffd358a33d8 EFLAGS: 00000202 ORIG_RAX: 00000000000000a6 RAX: ffffffffffffffda RBX: 000000000005d39f RCX: 000000000045c257 RDX: 0000000000403520 RSI: 0000000000000002 RDI: 00007ffd358a3480 RBP: 0000000000000629 R08: 0000000000000000 R09: 000000000000000c R10: 0000000000000006 R11: 0000000000000202 R12: 00007ffd358a4510 R13: 000000000111e940 R14: 0000000000000000 R15: 00007ffd358a4510 Showing all locks held in the system: 1 lock held by khungtaskd/1013: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4541 1 lock held by rsyslogd/7101: #0: (&f->f_pos_lock){+.+.}, at: [] __fdget_pos+0xab/0xd0 fs/file.c:769 2 locks held by getty/7223: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156 2 locks held by getty/7224: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156 2 locks held by getty/7225: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156 2 locks held by getty/7226: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156 2 locks held by getty/7227: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156 2 locks held by getty/7228: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156 2 locks held by getty/7229: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.0/7263: #0: (&type->i_mutex_dir_key#8){++++}, at: [] inode_lock_shared include/linux/fs.h:728 [inline] #0: (&type->i_mutex_dir_key#8){++++}, at: [] lookup_slow+0x138/0x440 fs/namei.c:1673 #1: (&fi->mutex){+.+.}, at: [] fuse_lock_inode+0xbc/0xf0 fs/fuse/inode.c:365 2 locks held by syz-executor.0/20141: #0: (&type->i_mutex_dir_key#8){++++}, at: [] inode_lock_shared include/linux/fs.h:728 [inline] #0: (&type->i_mutex_dir_key#8){++++}, at: [] lookup_slow+0x138/0x440 fs/namei.c:1673 #1: (&fi->mutex){+.+.}, at: [] fuse_lock_inode+0xbc/0xf0 fs/fuse/inode.c:365 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1013 Comm: khungtaskd Not tainted 4.14.138 #34 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+0x138/0x19c lib/dump_stack.c:53 nmi_cpu_backtrace.cold+0x57/0x94 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x141/0x189 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:140 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline] watchdog+0x5e7/0xb90 kernel/hung_task.c:274 kthread+0x319/0x430 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff861be0de