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

[David Vrabel <david.vrabel@citrix.com>]

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.

David