INFO: task syz-executor1:8278 blocked for more than 140 seconds. Not tainted 4.18.0+ #196 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor1 D26472 8278 4484 0x00000004 Call Trace: context_switch kernel/sched/core.c:2823 [inline] __schedule+0x87c/0x1ec0 kernel/sched/core.c:3471 schedule+0xfb/0x450 kernel/sched/core.c:3515 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3573 __mutex_lock_common kernel/locking/mutex.c:1003 [inline] __mutex_lock+0xbf9/0x1700 kernel/locking/mutex.c:1073 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1088 __fdget_pos+0x1bb/0x200 fs/file.c:766 fdget_pos include/linux/file.h:70 [inline] ksys_write+0x7f/0x260 fs/read_write.c:593 __do_sys_write fs/read_write.c:610 [inline] __se_sys_write fs/read_write.c:607 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:607 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457089 Code: 08 e8 3b a9 fb ff 48 8b 44 24 20 48 8b 4c 24 18 48 8b 54 24 38 48 8b 7c 24 48 eb 8d 48 8b 6c 24 50 48 83 c4 58 c3 48 89 04 24 <48> 89 5c 24 08 e8 0d a9 fb ff 48 8b 44 24 40 48 8b 4c 24 48 48 8b RSP: 002b:00007f3562712c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f35627136d4 RCX: 0000000000457089 RDX: 0000000000000015 RSI: 0000000020000600 RDI: 0000000000000009 RBP: 00000000009301e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000004d7298 R14: 00000000004ca4ed R15: 0000000000000002 Showing all locks held in the system: 1 lock held by khungtaskd/774: #0: 000000000b465cfa (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x428 kernel/locking/lockdep.c:4461 2 locks held by rsyslogd/4345: #0: 00000000b3377073 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766 #1: 00000000b32e9a21 (&(&zone->lock)->rlock){..-.}, at: __debug_check_no_obj_freed lib/debugobjects.c:777 [inline] #1: 00000000b32e9a21 (&(&zone->lock)->rlock){..-.}, at: debug_check_no_obj_freed+0x16c/0x595 lib/debugobjects.c:818 2 locks held by getty/4435: #0: 000000009bd4f006 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000000766ea3b (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4436: #0: 00000000987239f7 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000009ef6b89d (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4437: #0: 0000000021dc77de (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000080618a75 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4438: #0: 00000000591551a7 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000e287fa9d (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4439: #0: 00000000c703dfaf (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000001daf8873 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4440: #0: 00000000bf44a3f9 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000fff86750 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4441: #0: 0000000059189a88 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000007e4f7f38 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by syz-executor1/8239: #0: 0000000049fe4d5e (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766 #1: 000000005da528dc (sb_writers#17){.+.+}, at: file_start_write include/linux/fs.h:2755 [inline] #1: 000000005da528dc (sb_writers#17){.+.+}, at: vfs_writev+0x2bd/0x360 fs/read_write.c:1003 1 lock held by syz-executor1/8278: #0: 0000000049fe4d5e (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 774 Comm: khungtaskd Not tainted 4.18.0+ #196 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+0x1c9/0x2b4 lib/dump_stack.c:113 nmi_cpu_backtrace.cold.3+0x48/0x88 lib/nmi_backtrace.c:101 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:144 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:196 [inline] watchdog+0x9c4/0xf80 kernel/hung_task.c:252 kthread+0x35a/0x420 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413 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:56