linux-kernel - Re: x86/mce: suspicious RCU usage in 4.13.4

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Message-ID: <20171101200730.dvfhyf6baqphhrtz@intel.com>
Date:   Wed, 1 Nov 2017 13:07:31 -0700
From:   "Luck, Tony" <tony.luck@...el.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Laura Abbott <labbott@...hat.com>, Andi Kleen <ak@...ux.intel.com>,
        Jeremy Cline <jcline@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: x86/mce: suspicious RCU usage in 4.13.4

On Wed, Nov 01, 2017 at 05:47:54PM +0100, Borislav Petkov wrote:
> On Wed, Nov 01, 2017 at 07:56:20AM -0700, Laura Abbott wrote:
> > Did these get queued up somewhere? I know last week was OSSEU/Ksummit
> > so people may still be playing catch-up.
> 
> Ah, thanks for the reminder.
> 
> /me goes and dusts it off.
> 
> Ok, here it is, injecting some MCEs in a guest seems to work fine,
> mcelog logs them.
> 
> Tony?

Yup. I did a bit more testing on bare metal with injection:

1) Just one error
	Worked
2) "kill -STOP `pgrep mcelog`" ; inject 5 errors ; "kill -CONT `pgrep mcelog`"
	Worked (all five errors reported correctly)
3) "kill -STOP `pgrep mcelog`" ; inject 35 errors ; "kill -CONT `pgrep mcelog`"
	mcelog reported Warning: MCE buffer is overflowed.
	First 32 (MCE_LOG_LEN) errors reported correctly.

Reviewed-and-tested-by: Tony Luck <tony.luck@...el.com>

-Tony