Re: Major KVM issues with kernel 4.5 on the host

[Marc Haber <mh+linux-kernel@zugschlus.de>]

On Thu, Apr 14, 2016 at 07:30:43PM +0200, Paolo Bonzini wrote:
> On 14/04/2016 18:47, Marc Haber wrote:
> >> > Ok, then I guess bisection is needed.  Please first try commit
> >> > 45bdbcfdf241.
> > I did git checkout 45bdbcfdf241 and built the resulting kernel
> > 4.4.0-rc5. This one has now been running for ten hours, which is
> > threefold the longest time that a faulty kernel has held before a VM
> > experienced corruption. So I guess, that one is fine.
> 
> Interesting, this means it's not a KVM bug.  You can ignore my patch
> from yesterday (though we'll get it in anyway).
> 
> > Since 4.5.0-rc1 is bad, I guess I do:
> > 
> > git checkout 45bdbcfdf241
> > git bisect start
> > git bisect good
> > git bisect bad v4.5.0-rc1
> 
> This is correct but you also want to do
> 
> git bisect good 4.4.0
> git bisect good 4.4.0-rc5
> 
> so that bisection basically works through the commits in the merge window.

So I start over from this:

[47/544]mh@fan:~/linux/debug/linux$ git checkout 45bdbcfdf241
HEAD is now at 45bdbcf... kvm: x86: Fix vmwrite to SECONDARY_VM_EXEC_CONTROL
[48/545]mh@fan:~/linux/debug/linux$ git bisect start
[49/546]mh@fan:~/linux/debug/linux$ git bisect good
[50/547]mh@fan:~/linux/debug/linux$ git bisect bad v4.5-rc1
Bisecting: 5761 revisions left to test after this (roughly 13 steps)
[cbd88cd4c07f9361914ab7fd7e21c9227986fe68] Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
[51/548]mh@fan:~/linux/debug/linux$ git bisect good v4.4
Bisecting: 5468 revisions left to test after this (roughly 12 steps)
[f9a03ae123c92c1f45cd2ca88d0f6edd787be78c] Merge tag 'for-f2fs-4.5' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs
[52/549]mh@fan:~/linux/debug/linux$ git bisect good v4.4-rc5
Bisecting: 5468 revisions left to test after this (roughly 12 steps)
[f9a03ae123c92c1f45cd2ca88d0f6edd787be78c] Merge tag 'for-f2fs-4.5' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs
[53/550]mh@fan:~/linux/debug/linux$

This is going to take a few days as detecting a "bad" version may take
a few hours.

Greetings
Marc

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