Messages in this thread | | | Date | Fri, 21 Nov 2014 17:41:40 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH v3] x86/mce: Try printing all machine check banks known before panic |
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On Fri, Nov 21, 2014 at 09:20:59AM +0800, rui wang wrote: > We've found there are cases after mce_log() has been called, we then > decide to panic, but print_mce() can't find anything in the mcelog > buffer. I think the mcelog buffer can be consumed by the user space > daemon (possibly on a different CPU). We may end up seeing the "panic > from unknown source" message without printing any mca banks, which is > one of the cases where this bug was originated.
Ok, so modify the mcelog buffer to not zero out its entries when they're being read out in userspace through mce_chrdev_read() but simply to leave them in. Then you can read them out again on panic time. The mce log buffer will have to become a circular buffer or something like that.
-- Regards/Gruss, Boris.
Sent from a fat crate under my desk. Formatting is fine. --
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