Messages in this thread | | | Date | Mon, 11 Jul 2011 17:55:41 -0400 | From | Don Zickus <> | Subject | Re: pstore dump inside an nmi handler |
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On Fri, Jul 08, 2011 at 02:40:13PM -0700, Luck, Tony wrote: > > Inside pstore_dump(), the first thing it tries to grab is a mutex_lock() > > (inside an nmi hander). This seems to be the root cause of my problems. > > Someone else pointed out that mutex_lock() is a problem here too. They > wondered whether spin_lock_irqsave() would work - or whether pstore > backends were allowed to sleep - to which I said I hoped they didn't, > but wasn't really sure what the future will hold. > > So ... ideas (and patches) are most welcome.
I tested the spin_lock_irqsave thing on my one box where it was failing and got past my initial problem into kdump. So that is a positive and I can post the patch for that. Though it probably isn't a complete solution, it is better than a mutex.
However, I have been scratching my head at a follow up problem, which is when I inject an error which produces an NMI->GHES->panic, the error record doesn't get stored under pstore (or maybe ERST too). I do see the ERST code follow all the correct steps in storing the kmsg_dump logs into the ERST table. Just on the reboot, when I mount pstore it isn't there.
When I perform an 'echo c > /proc/sysrq-trigger', it shows up on the reboot. Not sure what can be going wrong. I cc'd Ying with hopes he might have some thoughts.
Cheers, Don
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