[Re: Possible KVM stable backport carried too far back?] On 27/01/2015 (Tue 15:35) Greg KH wrote:
> On Tue, Jan 27, 2015 at 06:10:31PM -0500, Paul Gortmaker wrote:
> > Hi Greg,
> >
> > Someone working on a 3.10.x based -rt kernel traced a latency increase
> > back to the backport of 56cc2406d68c0f0950 ("KVM: nVMX: fix "acknowledge
> > interrupt on exit" when APICv is in use"). When they asked me for
> > assistance, I noticed that the commit had:
> >
> > Fixes: 77b0f5d67ff2781f36831cba79674c3e97bd7acf
> >
> > ...but 77b0f5 only appeared in v3.16-rc4~21^2^2~32. Checking the stable
> > queue, it seems that it was added to 3.10.54, 3.14.18 and 3.16.2 -- but if
> > the Fixes tag is to be believed, then only 3.16.x should have this applied.
> >
> > I also checked to see if stable [you] backported 77b0f5d67ff to any
> > versions, thus expanding its applicability, but it/you had not.
> >
> > Obviously a kernel based on -rt won't behave the same as vanilla stable
> > but regardless I figured I'd mention the discrepancy I found above since
> > it might cause issues for other people on the stable kernels as well.
>
> I have no idea, I did that back in August, I can't remember what I
> applied last week :(
I know where you are coming from; I have goldfish syndrome too. ;)
>
> Do you think I should revert it? It doesn't seem to have caused any
> problems, as no one has noticed any issues...
Well, my concern was that possibly other people just fixed it locally
and did not provide feedback -- I did not want to be a part of that
group. I do intend to revert it locally since it has been determined as
a cause for a regression.
In addition to giving you and other stable users a heads-up, I was kind
of hoping the kvm folks [cc'd] could add in a comment like 'Yes Greg,
please revert because ...'
Paul.
--
>
> thanks,
>
> greg k-h
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