Re: [Xen-devel] [linux-3.14 bisection] complete test-amd64-i386-xl-qcow2

[Luis Henriques <luis.henriques@canonical.com>]

On Thu, Sep 03, 2015 at 12:16:39PM +0100, David Vrabel wrote:
> On 03/09/15 12:05, Luis Henriques wrote:
> > On Wed, Sep 02, 2015 at 10:18:32AM +0100, Ian Campbell wrote:
> >> [resending to correct stable address, sorry folks]
> >>
> >> TL;DR: Any backport of 30b03d05e074 to earlier than commit 1401c00e59e
> >> ("xen/gntdev: convert priv->lock to a mutex", which was added in v4.0)
> >> needs $something doing to it, either s/mutex/spinlock/ or (more likely)
> >> backporting of 1401c00e59e too.
> >>
> >> Looking at LTS:
> >>
> >> 3.18.y:	  Backported both.
> >> 3.16.y:	  Has backported neither
> >> 3.14.y:	* Only backported 30b03d05e074
> >> 3.12.y:	  Has backported neither
> >> 3.10.y:	* Only backported 30b03d05e074
> >> 3.4.y:	  Has backported neither
> >> 3.2.y:	  Has backported neither
> >>
> >> So AFAICT 3.14.y and 3.10.y need fixes, probably following 3.18 and
> >> backporting 1401c00e59e.
> >>
> >> 3.16/12/4/2 might need to be careful if they subsequently pick up 30b03d05.
> >>
> > 
> > Thank you Ian.  In fact, I had explicitly dropped 30b03d05e074
> > ("xen/gntdevt: Fix race condition in gntdev_release()") from the 3.16
> > kernel and notified stable maintainers about this problem (in a reply to a
> > 3.12 review email).
> > 
> > Simply replacing the mutex by the spinlock in this commit seems to cause
> > problems (sleep in atomic) as pointed out by Jiri in other thread.
> > 
> > Since 1401c00e59ea ("xen/gntdev: convert priv->lock to a mutex") is a
> > clean cherry-pick for 3.16 (and probably to older kernels as well), I'm
> > happy to pick both commits if you can confirm they are both good for older
> > stable kernels (they seem to be!)
> 
> You can take both 1401c00e59ea and 30b03d05e074.

Awesome, thanks for confirming.  I'll queue them for the next release of
3.16.

Cheers,
--
Luís