Re: [PATCH] drm/i915: annote drop_caches debugfs interface with lockdep

[Peter Zijlstra <peterz@infradead.org>]

On Sun, Mar 12, 2017 at 09:53:40PM +0100, Daniel Vetter wrote:

> Peter/Ingo,
> 
> We want this to validate the i915 shrinker locking in our fast tests
> without thrashing badly (that takes too long, we can only thrash in
> the extended runs). Can you pls take a look and if it's ok ack for
> merging through drm-intel.git?

Hurm, I was going to rework all that soonish; have a look here:

 https://lkml.kernel.org/r/20170302134031.GG6536@twins.programming.kicks-ass.net

The immediate problem is that I made the annotation private to mm/
there, I suppose I could fix that.

> ---
>  drivers/gpu/drm/i915/i915_debugfs.c | 2 ++
>  kernel/locking/lockdep.c            | 2 ++
>  2 files changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 82fb005a5e22..fbe761a3f5bd 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -4273,6 +4273,7 @@ i915_drop_caches_set(void *data, u64 val)
>  	if (val & (DROP_RETIRE | DROP_ACTIVE))
>  		i915_gem_retire_requests(dev_priv);
>  
> +	lockdep_set_current_reclaim_state(GFP_KERNEL);
>  	if (val & DROP_BOUND)
>  		i915_gem_shrink(dev_priv, LONG_MAX, I915_SHRINK_BOUND);
>  
> @@ -4281,6 +4282,7 @@ i915_drop_caches_set(void *data, u64 val)
>  
>  	if (val & DROP_SHRINK_ALL)
>  		i915_gem_shrink_all(dev_priv);
> +	lockdep_clear_current_reclaim_state();
>  
>  unlock:
>  	mutex_unlock(&dev->struct_mutex);
> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
> index 12e38c213b70..508cbf31d43e 100644
> --- a/kernel/locking/lockdep.c
> +++ b/kernel/locking/lockdep.c
> @@ -3856,11 +3856,13 @@ void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
>  {
>  	current->lockdep_reclaim_gfp = gfp_mask;
>  }
> +EXPORT_SYMBOL_GPL(lockdep_set_current_reclaim_state);
>  
>  void lockdep_clear_current_reclaim_state(void)
>  {
>  	current->lockdep_reclaim_gfp = 0;
>  }
> +EXPORT_SYMBOL_GPL(lockdep_clear_current_reclaim_state);
>  
>  #ifdef CONFIG_LOCK_STAT
>  static int
> -- 
> 2.11.0
>