From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Widawsky Subject: Re: [PATCH] drm/i915: Fix ordering of unbind vs unpin pages Date: Tue, 3 Dec 2013 16:07:14 -0800 Message-ID: <20131204000714.GA32105@bwidawsk.net> References: <1385978882-11007-1-git-send-email-chris@chris-wilson.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail.bwidawsk.net (bwidawsk.net [166.78.191.112]) by gabe.freedesktop.org (Postfix) with ESMTP id 3ECE1105839 for ; Tue, 3 Dec 2013 16:07:22 -0800 (PST) Content-Disposition: inline In-Reply-To: <1385978882-11007-1-git-send-email-chris@chris-wilson.co.uk> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces@lists.freedesktop.org Errors-To: intel-gfx-bounces@lists.freedesktop.org To: Chris Wilson Cc: intel-gfx@lists.freedesktop.org List-Id: intel-gfx@lists.freedesktop.org On Mon, Dec 02, 2013 at 10:08:02AM +0000, Chris Wilson wrote: > It is useful to assert that if the object is bound, then it must have > its pages pinned to prevent the shrinker from reaping its backing store. > This is even more useful with the introduction of real-ppgtt whereupon > we may have the object bound into several vma, with each instance > pinning the backing store. This assertion breaks down during unbind > where we unpinned the backing store before decoupling the vma binding. > This can be fixed with a trivial reording of the unbind sequence, which > reinforces the > > pin pages > bind to vma > ... > unbind from vma > unpin pages > > concept. > > Signed-off-by: Chris Wilson > Cc: Ben Widawsky A comment in the code why the page unpinning happens last would be nice, but not mandatory. Reviewed-by: Ben Widawsky Tested-by: Ben Widawsky > --- > drivers/gpu/drm/i915/i915_gem.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c > index 6312d61f5198..5fef29a5d6af 100644 > --- a/drivers/gpu/drm/i915/i915_gem.c > +++ b/drivers/gpu/drm/i915/i915_gem.c > @@ -2755,7 +2755,6 @@ int i915_vma_unbind(struct i915_vma *vma) > vma->unbind_vma(vma); > > i915_gem_gtt_finish_object(obj); > - i915_gem_object_unpin_pages(obj); > > list_del(&vma->mm_list); > /* Avoid an unnecessary call to unbind on rebind. */ > @@ -2763,7 +2762,6 @@ int i915_vma_unbind(struct i915_vma *vma) > obj->map_and_fenceable = true; > > drm_mm_remove_node(&vma->node); > - > i915_gem_vma_destroy(vma); > > /* Since the unbound list is global, only move to that list if > @@ -2771,6 +2769,8 @@ int i915_vma_unbind(struct i915_vma *vma) > if (list_empty(&obj->vma_list)) > list_move_tail(&obj->global_list, &dev_priv->mm.unbound_list); > > + i915_gem_object_unpin_pages(obj); > + > return 0; > } > > -- > 1.8.5 > -- Ben Widawsky, Intel Open Source Technology Center