igt@kms_vblank@pipe-b-wait-forked-busy - timeout - Per-test timeout exceeded. Killing the current test with SIGQUIT.

https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_7731/shard-glk2/igt@kms_vblank@pipe-b-wait-forked-busy.html

Err	
Received signal SIGQUIT.
Stack trace: 
 #0 [fatal_sig_handler+0xd6]
 #1 [killpg+0x40]
 #2 [write+0x15]
 #3 [igt_writen+0x33]
 #4 [igt_sysfs_vprintf+0x96]
 #5 [igt_sysfs_printf+0x8f]
 #6 [igt_drop_caches_set+0x35]
 #7 [drm_open_driver+0x60]
 #8 [drm_open_driver_master+0x6]
 #9 [__igt_unique____real_main530+0x305]
 #10 [main+0x27]
 #11 [__libc_start_main+0xf3]
 #12 [_start+0x2a]
Dmesg	
<6> [800.915853] Console: switching to colour dummy device 80x25
<6> [800.917464] [IGT] kms_vblank: executing
<4> [921.118992] [IGT] Per-test timeout exceeded. Killing the current test with SIGQUIT.
<6> [921.119066] sysrq: Show State
<6> [921.119099] task:systemd         state:S stack:11672 pid:    1 ppid:     0 flags:0x00000000
<6> [921.119112] Call Trace:
<6> [921.119116]  <TASK>
<6> [921.119126]  __schedule+0x30b/0xa80
<6> [921.119147]  schedule+0x4e/0xd0
<6> [921.119153]  schedule_hrtimeout_range_clock+0x11d/0x130
<6> [921.119160]  ? do_epoll_wait+0x759/0x8f0
<6> [921.119170]  ? _raw_write_unlock_irq+0x1f/0x50
<6> [921.119176]  ? lockdep_hardirqs_on+0xbf/0x140
<6> [921.119185]  do_epoll_wait+0x76a/0x8f0
<6> [921.119200]  ? find_held_lock+0x2d/0xa0
<6> [921.119211]  ? ep_timeout_to_timespec.part.24+0xa0/0xa0
<6> [921.119304]  __x64_sys_epoll_wait+0x50/0x90
<6> [921.119311]  ? lockdep_hardirqs_on+0xbf/0x140
<6> [921.119321]  do_syscall_64+0x37/0x90
<6> [921.119328]  entry_SYSCALL_64_after_hwframe+0x63/0xcd
<6> [921.119334] RIP: 0033:0x7fa325ac65ce
<6> [921.119340] RSP: 002b:00007ffebc2bd8d0 EFLAGS: 00000293 ORIG_RAX: 00000000000000e8
<6> [921.119348] RAX: ffffffffffffffda RBX: 000055f32c829510 RCX: 00007fa325ac65ce
<6> [921.119351] RDX: 0000000000000051 RSI: 000055f32c965660 RDI: 0000000000000004
<6> [921.119355] RBP: ffffffffffffffff R08: 0000000000000000 R09: 0000000000000000
<6> [921.119359] R10: 00000000ffffffff R11: 0000000000000293 R12: 0000000000000001
<6> [921.119362] R13: 0000000000000051 R14: 000055f32b831883 R15: 0000000000000000
<6> [921.119387]  </TASK>
<6> [921.119390] task:kthreadd        state:S stack:14136 pid:    2 ppid:     0 flags:0x00004000
<6> [921.119401] Call Trace:
<6> [921.119405]  <TASK>
<6> [921.119414]  __schedule+0x30b/0xa80
<6> [921.119420]  ? kthreadd+0x129/0x160
<6> [921.119432]  ? kthreadd+0x8b/0x160
<6> [921.119436]  ? kthreadd+0x64/0x160
<6> [921.119441]  schedule+0x4e/0xd0
<6> [921.119447]  kthreadd+0x14b/0x160
<6> [921.119452]  ? kthread_is_per_cpu+0x20/0x20
<6> [921.119461]  ret_from_fork+0x1f/0x30
<6> [921.119489]  </TASK>
<6> [921.119492] task:rcu_gp          state:I stack:15032 pid:    3 ppid:     2 flags:0x00004000
<6> [921.119504] Call Trace:
<6> [921.119507]  <TASK>
<6> [921.119516]  __schedule+0x30b/0xa80
<6> [921.119522]  ? rescuer_thread+0x22f/0x390
<6> [921.119538]  schedule+0x4e/0xd0
<6> [921.119544]  rescuer_thread+0x24c/0x390
<6> [921.119552]  ? _raw_spin_unlock_irqrestore+0x3d/0x70
<6> [921.119563]  ? worker_thread+0x370/0x370
<6> [921.119569]  kthread+0xed/0x120
<6> [921.119573]  ? kthread_complete_and_exit+0x20/0x20
<6> [921.119582]  ret_from_fork+0x1f/0x30
<6> [921.119608]  </TASK>
<6> [921.119611] task:rcu_par_gp      state:I stack:15432 pid:    4 ppid:     2 flags:0x00004000
<6> [921.119623] Call Trace: