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| Started by | "Luck, Tony" <tony.luck@intel.com> |
|---|---|
| First post | 2016-09-16 22:30 +0200 |
| Last post | 2016-09-18 20:40 +0200 |
| Articles | 2 — 2 participants |
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RE: [RFC PATCH] x86: Do not panic if mce=2 is passed "Luck, Tony" <tony.luck@intel.com> - 2016-09-16 22:30 +0200
Re: [RFC PATCH] x86: Do not panic if mce=2 is passed Borislav Petkov <bp@alien8.de> - 2016-09-18 20:40 +0200
| From | "Luck, Tony" <tony.luck@intel.com> |
|---|---|
| Date | 2016-09-16 22:30 +0200 |
| Subject | RE: [RFC PATCH] x86: Do not panic if mce=2 is passed |
| Message-ID | <si7VL-1eB-7@gated-at.bofh.it> |
> For UE recovery support, current we need mce=2 in command line > and also disable panic_on_oops with sysctl. Please explain. I've never given mce=2 on command line, and have had my kernel recover from thousands of (injected) UE memory errors. -Tony
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| From | Borislav Petkov <bp@alien8.de> |
|---|---|
| Date | 2016-09-18 20:40 +0200 |
| Message-ID | <siPap-3cz-3@gated-at.bofh.it> |
| In reply to | #1485348 |
On Fri, Sep 16, 2016 at 08:28:44PM +0000, Luck, Tony wrote:
> > For UE recovery support, current we need mce=2 in command line
> > and also disable panic_on_oops with sysctl.
>
> Please explain. I've never given mce=2 on command line, and have
> had my kernel recover from thousands of (injected) UE memory errors.
So frankly, that panic_on_oops doesn't make a whole lotta sense to me.
It is promoting MCEs with severity MCE_UC_SEVERITY and higher to a
panic.
So let's look at those:
MCE_UC_SEVERITY, - we don't do anything special in the kernel for
those so just as well.
MCE_AR_SEVERITY, - those end up in the memory failure code if
they're memory errors
MCE_PANIC_SEVERITY, - causes panic
so if anything, panic_on_oops shouldn't control the panicking behavior
as tolerant does that already:
* Tolerant levels:
* 0: always panic on uncorrected errors, log corrected errors
* 1: panic or SIGBUS on uncorrected errors, log corrected errors
* 2: SIGBUS or log uncorrected errors (if possible), log corr. errors
* 3: never panic or SIGBUS, log all errors (for testing only)
IOW, I think that patch makes sense but please doublecheck my logic
above first.
Thanks.
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
--
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