INFO: task syz-executor.5:7868 blocked for more than 143 seconds. Not tainted 5.1.0-rc5-next-20190417 #27 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D24608 7868 1 0x80004004 Call Trace: context_switch kernel/sched/core.c:2817 [inline] __schedule+0x7d1/0x15c0 kernel/sched/core.c:3444 schedule+0xa8/0x260 kernel/sched/core.c:3508 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3567 __mutex_lock_common kernel/locking/mutex.c:1002 [inline] __mutex_lock+0x726/0x1310 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+0x2e5/0x61e kernel/acct.c:605 do_exit+0x17bd/0x2fa0 kernel/exit.c:866 do_group_exit+0x135/0x370 kernel/exit.c:980 get_signal+0x399/0x1d50 kernel/signal.c:2578 do_signal+0x87/0x1900 arch/x86/kernel/signal.c:818 exit_to_usermode_loop+0x244/0x2c0 arch/x86/entry/common.c:163 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:276 [inline] do_syscall_64+0x57e/0x670 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x412c6a Code: 3a 44 00 31 c0 e8 e6 e3 00 00 e9 2e fe ff ff 90 48 89 d6 bf 69 37 44 00 31 c0 e8 d1 e3 00 00 e9 ba fd ff ff 0f 1f 40 00 48 8b c8 00 00 00 ff 15 db 6a 24 00 85 c0 89 c5 0f 85 0d fe ff ff e9 RSP: 002b:00007fffbeeb2d48 EFLAGS: 00000246 ORIG_RAX: 000000000000003d RAX: fffffffffffffe00 RBX: 0000000000000000 RCX: 0000000000412c6a RDX: 0000000040000000 RSI: 00007fffbeeb2d80 RDI: ffffffffffffffff RBP: 0000000000001e87 R08: 0000000000000001 R09: 0000555555555940 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000005 R13: 00007fffbeeb2d80 R14: 000000000014701e R15: 00007fffbeeb2d90 Showing all locks held in the system: 1 lock held by khungtaskd/1043: #0: 000000001aacf775 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x27e kernel/locking/lockdep.c:5046 1 lock held by rsyslogd/7709: #0: 00000000a15c47b0 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801 2 locks held by getty/7820: #0: 00000000df38ed04 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 000000000e21fb9c (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 2 locks held by getty/7821: #0: 00000000243db557 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 00000000a0aa3784 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 2 locks held by getty/7822: #0: 00000000936a09f2 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 000000008b886d1a (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 2 locks held by getty/7823: #0: 000000006c1c0686 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 000000004c0450b8 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 2 locks held by getty/7824: #0: 00000000870735cd (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 00000000c4549853 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 2 locks held by getty/7825: #0: 00000000bccabd5d (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 00000000b45f98ce (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 2 locks held by getty/7826: #0: 00000000481c6255 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 00000000d55161b4 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.5/7868: #0: 00000000ae8bc967 (&acct->lock#2){+.+.}, at: acct_get kernel/acct.c:161 [inline] #0: 00000000ae8bc967 (&acct->lock#2){+.+.}, at: slow_acct_process kernel/acct.c:577 [inline] #0: 00000000ae8bc967 (&acct->lock#2){+.+.}, at: acct_process+0x2e5/0x61e kernel/acct.c:605 3 locks held by syz-executor.5/28661: #0: 00000000ae8bc967 (&acct->lock#2){+.+.}, at: acct_get kernel/acct.c:161 [inline] #0: 00000000ae8bc967 (&acct->lock#2){+.+.}, at: slow_acct_process kernel/acct.c:577 [inline] #0: 00000000ae8bc967 (&acct->lock#2){+.+.}, at: acct_process+0x2e5/0x61e kernel/acct.c:605 #1: 00000000355d8981 (sb_writers#3){.+.+}, at: file_start_write_trylock include/linux/fs.h:2832 [inline] #1: 00000000355d8981 (sb_writers#3){.+.+}, at: do_acct_process+0xf37/0x1150 kernel/acct.c:517 #2: 0000000077651013 (&sb->s_type->i_mutex_key#10){++++}, at: inode_trylock include/linux/fs.h:792 [inline] #2: 0000000077651013 (&sb->s_type->i_mutex_key#10){++++}, at: ext4_file_write_iter+0x257/0x11c0 fs/ext4/file.c:232 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1043 Comm: khungtaskd Not tainted 5.1.0-rc5-next-20190417 #27 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+0x172/0x1f0 lib/dump_stack.c:113 nmi_cpu_backtrace.cold+0x63/0xa4 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1be/0x236 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:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:204 [inline] watchdog+0x9b7/0xec0 kernel/hung_task.c:288 kthread+0x357/0x430 kernel/kthread.c:254 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 0 to CPUs 1: