linux-kernel - Re: random insta-reboots on AMD Phenom II

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Date:   Sun, 1 Oct 2017 15:07:01 +0200
From:   Adam Borowski <kilobyte@...band.pl>
To:     Borislav Petkov <bp@...en8.de>
Cc:     linux-kernel@...r.kernel.org, Andy Lutomirski <luto@...nel.org>,
        x86-ml <x86@...nel.org>
Subject: Re: random insta-reboots on AMD Phenom II

On Sat, Sep 30, 2017 at 01:53:02PM +0200, Borislav Petkov wrote:
> On Sat, Sep 30, 2017 at 01:29:03PM +0200, Adam Borowski wrote:
> > On Sat, Sep 30, 2017 at 01:11:37PM +0200, Borislav Petkov wrote:
> > > On Sat, Sep 30, 2017 at 04:05:16AM +0200, Adam Borowski wrote:

> Boot into -rc2+ and do as root:
> 
> # wrmsr -a 0xc0010015 0x1000018

Seems to help, thus it's indeed this issue.  I failed to mention that "once
per day" meant a day of regular use, of which heavy loads were only a tiny
fraction.  I've applied this register setting, then kept the machine busy
(mostly with randconfig kernel builds) for a day, no explosions yet -- so
there's a good chance the problem would have triggered.

> If the issue gets fixed then Mr. Luto better revert the new lazy TLB
> flushing fun'n'games for 4.14 before it is too late and that kernel
> releases b0rked.

I have no clue about these matters so I'll leave it to you guys.  But, as
the other report I see gives different effects (frequent segfaults vs rare
insta-reboots), you do want to include my machine in testing.

Thanks for the workaround!

Meow!
-- 
⢀⣴⠾⠻⢶⣦⠀ We domesticated dogs 36000 years ago; together we chased
⣾⠁⢰⠒⠀⣿⡁ animals, hung out and licked or scratched our private parts.
⢿⡄⠘⠷⠚⠋⠀ Cats domesticated us 9500 years ago, and immediately we got
⠈⠳⣄⠀⠀⠀⠀ agriculture, towns then cities.     -- whitroth on /.