Re: frequent softlockups with 3.10rc6.

[Dave Jones <davej@redhat.com>]

Took a lot longer to trigger this time. (13 hours of runtime).

This trace may still not be from the first lockup, as a flood of
them happened at the same time. 


# tracer: preemptirqsoff
#
# preemptirqsoff latency trace v1.1.5 on 3.10.0-rc7+
# --------------------------------------------------------------------
# latency: 389877255 us, #4/4, CPU#1 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:4)
#    -----------------
#    | task: trinity-main-9252 (uid:1000 nice:19 policy:0 rt_prio:0)
#    -----------------
#  => started at: vprintk_emit
#  => ended at:   vprintk_emit
#
#
#                  _------=> CPU#            
#                 / _-----=> irqs-off        
#                | / _----=> need-resched    
#                || / _---=> hardirq/softirq 
#                ||| / _--=> preempt-depth   
#                |||| /     delay             
#  cmd     pid   ||||| time  |   caller      
#     \   /      |||||  \    |   /           
trinity--9252    1dNh1    0us!: console_unlock <-vprintk_emit
trinity--9252    1dNh1 389877255us : console_unlock <-vprintk_emit
trinity--9252    1dNh1 389877255us+: stop_critical_timings <-vprintk_emit
trinity--9252    1dNh1 389877261us : <stack trace>
 => console_unlock
 => vprintk_emit
 => printk
 => rcu_check_callbacks
 => update_process_times
 => tick_sched_handle.isra.16
 => tick_sched_timer
 => __run_hrtimer
 => hrtimer_interrupt
 => smp_apic_timer_interrupt
 => apic_timer_interrupt
 => _raw_spin_lock
 => evict
 => iput
 => dput
 => proc_flush_task
 => release_task
 => wait_consider_task
 => do_wait
 => SyS_wait4
 => tracesys