linux-kernel - Re: [PATCH 4.0 077/105] drm/i915: Dont skip request retirement if the active list is empty

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Date:	Tue, 23 Jun 2015 10:29:13 +0300
From:	Jani Nikula <jani.nikula@...el.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org,
	Ville Syrjälä <ville.syrjala@...ux.intel.com>,
	Chris Wilson <chris@...is-wilson.co.uk>
Subject: Re: [PATCH 4.0 077/105] drm/i915: Dont skip request retirement if the active list is empty

On Fri, 19 Jun 2015, Greg Kroah-Hartman <gregkh@...uxfoundation.org> wrote:
> 4.0-stable review patch.  If anyone has any objections, please let me know.

The commit to be backported is already reverted in upstream, and I just
got an email from you backporting the revert as well... would be best to
*not* backport either of these:

commit 0aedb1626566efd72b369c01992ee7413c82a0c5
Author: Ville Syrjälä <ville.syrjala@...ux.intel.com>
Date:   Thu May 28 18:32:36 2015 +0300

    drm/i915: Don't skip request retirement if the active list is empty

commit 245ec9d85696c3e539b23e210f248698b478379c
Author: Jani Nikula <jani.nikula@...el.com>
Date:   Mon Jun 15 12:59:37 2015 +0300

    Revert "drm/i915: Don't skip request retirement if the active list is empty"

I only marked the revert cc: stable because the original was too.


BR,
Jani.



>
> ------------------
>
> From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@...ux.intel.com>
>
> commit 0aedb1626566efd72b369c01992ee7413c82a0c5 upstream.
>
> Apparently we can have requests even if though the active list is empty,
> so do the request retirement regardless of whether there's anything
> on the active list.
>
> The way it happened here is that during suspend intel_ring_idle()
> notices the olr hanging around and then proceeds to get rid of it by
> adding a request. However since there was nothing on the active lists
> i915_gem_retire_requests() didn't clean those up, and so the idle work
> never runs, and we leave the GPU "busy" during suspend resulting in a
> WARN later.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@...ux.intel.com>
> Reviewed-by: Chris Wilson <chris@...is-wilson.co.uk>
> Signed-off-by: Jani Nikula <jani.nikula@...el.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>
> ---
>  drivers/gpu/drm/i915/i915_gem.c |    3 ---
>  1 file changed, 3 deletions(-)
>
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -2732,9 +2732,6 @@ void i915_gem_reset(struct drm_device *d
>  void
>  i915_gem_retire_requests_ring(struct intel_engine_cs *ring)
>  {
> -	if (list_empty(&ring->request_list))
> -		return;
> -
>  	WARN_ON(i915_verify_lists(ring->dev));
>  
>  	/* Retire requests first as we use it above for the early return.
>
>

-- 
Jani Nikula, Intel Open Source Technology Center
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