INFO: task syz-executor.3:15464 blocked for more than 143 seconds. Not tainted 5.2.0-rc6-next-20190628 #25 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D24040 15464 1 0x80004004 Call Trace: context_switch kernel/sched/core.c:3252 [inline] __schedule+0x755/0x1580 kernel/sched/core.c:3878 schedule+0xa8/0x270 kernel/sched/core.c:3942 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4001 __mutex_lock_common kernel/locking/mutex.c:1003 [inline] __mutex_lock+0x751/0x1340 kernel/locking/mutex.c:1073 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1088 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+0x179d/0x2ea0 kernel/exit.c:867 do_group_exit+0x135/0x360 kernel/exit.c:981 get_signal+0x47c/0x2500 kernel/signal.c:2728 do_signal+0x87/0x1700 arch/x86/kernel/signal.c:815 exit_to_usermode_loop+0x251/0x2d0 arch/x86/entry/common.c:159 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline] syscall_return_slowpath arch/x86/entry/common.c:274 [inline] do_syscall_64+0x5a9/0x6a0 arch/x86/entry/common.c:299 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4134aa Code: 0d 63 06 3b 01 48 89 cf 48 c1 e9 03 4c 8b 05 45 06 3b 01 48 c1 ef 05 49 29 f8 49 8d 78 ff 48 83 e1 03 48 83 fa 10 0f 84 a7 04 <00> 00 44 0f b6 43 17 41 f6 c0 40 0f 85 58 04 00 00 4c 8b 03 48 8b RSP: 002b:00007ffe1ae95c08 EFLAGS: 00000246 ORIG_RAX: 000000000000003d RAX: fffffffffffffe00 RBX: 0000000000000000 RCX: 00000000004134aa RDX: 0000000040000000 RSI: 00007ffe1ae95c40 RDI: ffffffffffffffff RBP: 0000000000000ce7 R08: 0000000000000001 R09: 0000555555d4b940 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000007 R13: 00007ffe1ae95c40 R14: 00000000001cbccd R15: 00007ffe1ae95c50 Showing all locks held in the system: 1 lock held by khungtaskd/1047: #0: 000000006ffd0b70 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x27e kernel/locking/lockdep.c:5257 1 lock held by rsyslogd/8643: #0: 00000000edab8bdf (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801 2 locks held by getty/8733: #0: 000000000a83215d (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 0000000080e6d66c (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/8734: #0: 0000000019832737 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 0000000058ff21c5 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/8735: #0: 00000000b69da9a5 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 0000000012fa5185 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/8736: #0: 000000003bedc1d0 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 0000000005400353 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/8737: #0: 000000006d5a0e5e (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 000000005fd0cbca (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/8738: #0: 0000000059366174 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 00000000240d186b (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/8739: #0: 00000000602634d2 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 000000009b469ed7 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.3/15464: #0: 00000000638cc46b (&acct->lock#2){+.+.}, at: acct_get kernel/acct.c:161 [inline] #0: 00000000638cc46b (&acct->lock#2){+.+.}, at: slow_acct_process kernel/acct.c:577 [inline] #0: 00000000638cc46b (&acct->lock#2){+.+.}, at: acct_process+0x2e5/0x61e kernel/acct.c:605 3 locks held by syz-executor.3/7471: #0: 00000000638cc46b (&acct->lock#2){+.+.}, at: acct_get kernel/acct.c:161 [inline] #0: 00000000638cc46b (&acct->lock#2){+.+.}, at: slow_acct_process kernel/acct.c:577 [inline] #0: 00000000638cc46b (&acct->lock#2){+.+.}, at: acct_process+0x2e5/0x61e kernel/acct.c:605 #1: 00000000efc5793c (sb_writers#3){.+.+}, at: file_start_write_trylock include/linux/fs.h:2848 [inline] #1: 00000000efc5793c (sb_writers#3){.+.+}, at: do_acct_process+0xf29/0x1140 kernel/acct.c:517 #2: 00000000b6105fbc (&sb->s_type->i_mutex_key#10){++++}, at: inode_trylock include/linux/fs.h:798 [inline] #2: 00000000b6105fbc (&sb->s_type->i_mutex_key#10){++++}, at: ext4_file_write_iter+0x287/0x1430 fs/ext4/file.c:236 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1047 Comm: khungtaskd Not tainted 5.2.0-rc6-next-20190628 #25 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+0x70/0xb2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x23b/0x28b 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:249 [inline] watchdog+0xc54/0x1320 kernel/hung_task.c:333 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:353 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60