Re: drm: gem_object_free without struct_mutex

[Jesse Barnes <jbarnes@virtuousgeek.org>]

On Sat, 2 Jan 2010 16:46:07 +0200
Dan Carpenter <error27@gmail.com> wrote:

> On Wed, Dec 30, 2009 at 11:17:48PM +0100, Rafael J. Wysocki wrote:
> > [CC to Jesse.]
> > 
> > On Wednesday 30 December 2009, Hugh Dickins wrote:
> > > I've changed BUG_ON to WARN_ON in drm_gem.c (patch at bottom) to
> > > get this dmesg when I resume after suspend, instead of crashing.
> > > 
> > > Perhaps it's a patch that should go in, perhaps not, but obviously
> > > the real problem lies elsewhere.  Happens with 2.6.33-rc1 and
> > > -rc2.
> > > 
> > > No surprise if I'm stupidly misconfigured to get the "pin power
> > > context" error in the first place (.config on demand), but I
> > > don't deserve to BUG!
> > > 
> 
> The problem is dev_priv->mm.suspended which was set in i915_suspend().
> 
> In i915_resume()
> 
>    107          i915_restore_state(dev);
> 
> The i915_restore_state() fails because i915_gem_object_bind_to_gtt()
> does this:
> 
>         if (dev_priv->mm.suspended)
>                 return -EBUSY;
> 
>    108  
>    109          intel_opregion_init(dev, 1);
>    110  
>    111          /* KMS EnterVT equivalent */
>    112          if (drm_core_check_feature(dev, DRIVER_MODESET)) {
>    113                  mutex_lock(&dev->struct_mutex);
>    114                  dev_priv->mm.suspended = 0;
> 
> We do set the dev_priv->mm.suspended here but it's too late.
> 
> Not sure the fix though...

I think this one should be fixed by Chris's recent patchset.  Should
land in Eric's tree soon.

-- 
Jesse Barnes, Intel Open Source Technology Center