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    SubjectRe: pstore dump inside an nmi handler
    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.

    EFI can't sleep (at least, not as far as the kernel's concerned), so
    we're safe there. I think it's fair to assume atomicity here - crash
    dumping is a pretty specific situation. Although we may need to think
    about whether pstore should be saving reboot and poweroff in that case.

    Matthew Garrett |

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