Brad Campbell <lists2...@fnarfbargle.com> wrote:

> 
> On 13/04/15 22:02, Paolo Bonzini wrote:
>> On 13/04/2015 14:45, Brad Campbell wrote:
>>> G'day Paolo,
>>> 
>>> Yes, on AMD and I've tried hard to reproduce it on Intel and been unable
>>> to thus far.
>>> 
>>> Now you mention it may be AMD specific, I have a spare motherboard and
>>> processor sitting in a drawer. I'll bolt it together tomorrow and see if
>>> I can reproduce it on another AMD machine. Two machines should let me
>>> test it twice as fast.
>>> 
>>> I got a fail this afternoon, so I'm due to reboot tonight. I'll just
>>> revert that one suspect commit from a known bad kernel and see if that
>>> cleans it up. If not then I'll work through the remainder of the
>>> information in your mail. I really appreciate the attention you've paid
>>> to this, it has been a frustrating bug for me because I'm in a position
>>> of not knowing what I don't know, and obviously doing something wrong in
>>> very long bisection processes.
>> Actually, if you have time to change your course of action, please
>> revert the one that Nadav pointed out (f210f7572bed, KVM: x86:
>> Fix lost interrupt on irr_pending race) or cherry-pick it on top of 3.17.
>> 
>> Paolo
> Ok, I think we have a winner. Patch manually plopped on top of vanilla 3.17. 
> It has never gone for anywhere near this long on a bad kernel.
> 
> brad@srv:~$ uptime
> 23:24:48 up 6 days,  1:01,  3 users,  load average: 1.48, 1.95, 2.48
> 
> So this patch went into the kernel during the 3.19 release cycle? Affected 
> kernels 3.16-3.18?

Actually, the original bug seemed to be introduced by commit
33e4c68656a2e461b296ce714ec322978de85412 "KVM: Optimize searching for
highest IRR”. So the bug goes all the way back to 2.6.32. The race that this
patch fixes just became more apparent (i.e., likely to happen) on 3.16. It
is fixed in 3.19.

I guess Paolo would push it to stable now. Right?

Regards,
Nadav

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