Re: [Intel-gfx] [PATCH 1/2] drm/i915: Fix a potential UAF at device unload

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Sep 23, 2022 at 09:35:14AM +0200, Nirmoy Das wrote:
> i915_gem_drain_freed_objects() might not be enough to
> free all the objects and RCU delayed work might get
> scheduled after the i915 device struct gets freed.
> 
> Call i915_gem_drain_workqueue() to catch all RCU delayed work.

shard-snb is stil hitting the mm.shrink_count WARNn reliably,
and things go downhill after that.

> 
> Suggested-by: Chris Wilson <chris.p.wilson@intel.com>
> Acked-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_gem.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 88df9a35e0fe..7541028caebd 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -1278,7 +1278,7 @@ void i915_gem_init_early(struct drm_i915_private *dev_priv)
>  
>  void i915_gem_cleanup_early(struct drm_i915_private *dev_priv)
>  {
> -	i915_gem_drain_freed_objects(dev_priv);
> +	i915_gem_drain_workqueue(dev_priv);
>  	GEM_BUG_ON(!llist_empty(&dev_priv->mm.free_list));
>  	GEM_BUG_ON(atomic_read(&dev_priv->mm.free_count));
>  	drm_WARN_ON(&dev_priv->drm, dev_priv->mm.shrink_count);
> -- 
> 2.37.3

-- 
Ville Syrjälä
Intel