Messages in this thread | | | Date | Wed, 14 Aug 2013 11:23:53 -0400 | From | Waiman Long <> | Subject | Re: [PATCH v3 0/3] qrwlock: Introducing a queue read/write lock implementation |
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On 08/14/2013 06:20 AM, Ingo Molnar wrote: > * Waiman Long<waiman.long@hp.com> wrote: > >> >> I would like to share with you a rwlock related system crash that I >> encountered during my testing with hackbench on an 80-core DL980. The >> kernel crash because of a "watchdog detected hard lockup on cpu 79". The >> crashing CPU was running "write_lock_irq(&tasklist_lock)" in >> forget_original_parent() of the exit code path when I interrupted the >> hackbench which was spawning thousands of processes. Apparently, the >> remote CPU was not able to get the lock for a sufficient long time due >> to the unfairness of the rwlock which I think my version of queue rwlock >> will be able to alleviate this issue. >> >> So far, I was not able to reproduce the crash. I will try to see if I >> could more consistently reproduce it. > Was it an actual crash/lockup, or a longish hang followed by a lock > detector splat followed by the system eventually recovering back to > working order? > > Thanks, > > Ingo
It was an actual crash initiated by the NMI handler. I think the system was in a halt state after that.
Regards, Longman
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