Messages in this thread | | | Date | Tue, 10 Nov 2015 12:21:01 +0100 | From | Borislav Petkov <> | Subject | Re: [RFC PATCH 0/3] Machine check recovery when kernel accesses poison |
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On Mon, Nov 09, 2015 at 10:26:08AM -0800, Tony Luck wrote: > This is a first draft to show the direction I'm taking to > make it possible for the kernel to recover from machine > checks taken while kernel code is executing.
Just a general, why-do-we-do-this, question: on big systems, the memory occupied by the kernel is a very small percentage compared to whole RAM, right? And yet we want to recover from there too? Not, say, kexec...
> Note that I also fudge the return value. I'd like in the future > to be able to write a "mcsafe_copy_from_user()" function that > would be annotated both for page faults, to return a count of > bytes uncopied, or an indication that there was a machine check. > Hence the BIT(63) bit. Internal feedback suggested we'd need > some IS_ERR() like macros to help users decode what happened > to take the right action. But this is "RFC" to see if people > have better ideas on how to handle this.
Hmm, shouldn't this be using MF_ACTION_REQUIRED or even maybe a new MF_ flag which is converted into a BUS_MCEERR_AR si_code and thus current gets a signal?
Only setting bit 63 looks a bit flaky to me...
-- Regards/Gruss, Boris.
ECO tip #101: Trim your mails when you reply.
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