INFO: task syz-executor3:2829 blocked for more than 140 seconds. Not tainted 4.19.0-next-20181102+ #104 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor3 D18344 2829 1 0x80000006 Call Trace: context_switch kernel/sched/core.c:2831 [inline] __schedule+0x8cf/0x21d0 kernel/sched/core.c:3472 schedule+0xfe/0x460 kernel/sched/core.c:3516 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3574 __mutex_lock_common kernel/locking/mutex.c:1002 [inline] __mutex_lock+0xaff/0x16f0 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 acct_get kernel/acct.c:161 [inline] slow_acct_process kernel/acct.c:577 [inline] acct_process+0x48b/0x875 kernel/acct.c:605 do_exit+0x1b84/0x26d0 kernel/exit.c:857 do_group_exit+0x177/0x440 kernel/exit.c:970 get_signal+0x8a8/0x1970 kernel/signal.c:2517 do_signal+0x9c/0x21c0 arch/x86/kernel/signal.c:816 exit_to_usermode_loop+0x2e5/0x380 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath arch/x86/entry/common.c:268 [inline] do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x41124a Code: 00 00 48 8b 44 24 20 48 8b 80 28 01 00 00 8b 0c 24 89 08 48 8b 44 24 28 48 89 04 24 48 8b 44 24 30 48 89 44 24 08 e8 95 43 01 <00> 48 8b 6c 24 10 48 83 c4 18 c3 e8 f6 8c 04 00 eb a4 cc cc cc cc RSP: 002b:00007fffa8269f98 EFLAGS: 00000246 ORIG_RAX: 000000000000003d RAX: fffffffffffffe00 RBX: 0000000000bb499b RCX: 000000000041124a RDX: 0000000040000000 RSI: 00007fffa8269fd0 RDI: ffffffffffffffff RBP: 00000000000002c7 R08: 0000000000000001 R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000bb4940 R13: 00000000000c44ff R14: 000000000000007e R15: 0000000000000003 Showing all locks held in the system: 1 lock held by khungtaskd/1008: #0: 00000000c1cf4854 (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x424 kernel/locking/lockdep.c:4379 2 locks held by rsyslogd/5520: #0: 00000000899ae6e5 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766 #1: 00000000bfa02510 (&rq->lock){-.-.}, at: rq_lock kernel/sched/sched.h:1126 [inline] #1: 00000000bfa02510 (&rq->lock){-.-.}, at: __schedule+0x236/0x21d0 kernel/sched/core.c:3410 2 locks held by getty/5611: #0: 0000000024638118 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000c0f96e0b (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/5612: #0: 000000001d413fda (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000aefaa9f3 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/5613: #0: 0000000070c53b86 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000bedc8558 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/5614: #0: 00000000d7a0ad4e (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000d1671801 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/5615: #0: 00000000234b0aec (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000dcf05ce3 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/5616: #0: 00000000b48c14f2 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000002c9253e8 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/5617: #0: 000000008edc68d9 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000c370e1f0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 1 lock held by syz-executor3/2829: #0: 0000000077481069 (&acct->lock#2){+.+.}, at: acct_get kernel/acct.c:161 [inline] #0: 0000000077481069 (&acct->lock#2){+.+.}, at: slow_acct_process kernel/acct.c:577 [inline] #0: 0000000077481069 (&acct->lock#2){+.+.}, at: acct_process+0x48b/0x875 kernel/acct.c:605 3 locks held by syz-executor3/8045: #0: 0000000077481069 (&acct->lock#2){+.+.}, at: acct_get kernel/acct.c:161 [inline] #0: 0000000077481069 (&acct->lock#2){+.+.}, at: slow_acct_process kernel/acct.c:577 [inline] #0: 0000000077481069 (&acct->lock#2){+.+.}, at: acct_process+0x48b/0x875 kernel/acct.c:605 #1: 00000000086f1a22 (sb_writers#3){.+.+}, at: file_start_write_trylock include/linux/fs.h:2832 [inline] #1: 00000000086f1a22 (sb_writers#3){.+.+}, at: do_acct_process+0x1338/0x1660 kernel/acct.c:517 #2: 00000000b47be3ab (&sb->s_type->i_mutex_key#10){++++}, at: inode_trylock include/linux/fs.h:784 [inline] #2: 00000000b47be3ab (&sb->s_type->i_mutex_key#10){++++}, at: ext4_file_write_iter+0x2a1/0x1420 fs/ext4/file.c:232 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1008 Comm: khungtaskd Not tainted 4.19.0-next-20181102+ #104 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+0x244/0x39d lib/dump_stack.c:113 nmi_cpu_backtrace.cold.2+0x5c/0xa1 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1e8/0x22a 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:205 [inline] watchdog+0xb4c/0x1060 kernel/hung_task.c:289 kthread+0x35a/0x440 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352 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:57