linux-kernel - [PATCH 4.1 140/267] drm/i915/ppgtt: Break loop in gen8_ppgtt_clear

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Date:	Fri, 31 Jul 2015 12:39:51 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org,
	Mika Kuoppala <mika.kuoppala@...ux.intel.com>,
	John Harrison <john.c.harrison@...el.com>,
	Michel Thierry <michel.thierry@...el.com>,
	Mika Kuoppala <mika.kuoppala@...el.com>,
	Jani Nikula <jani.nikula@...el.com>
Subject: [PATCH 4.1 140/267] drm/i915/ppgtt: Break loop in gen8_ppgtt_clear_range failure path

4.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Michel Thierry <michel.thierry@...el.com>

commit 00245266b4be4fbe989ee073663f56716da6c1f3 upstream.

If for some reason [1], the page directory/table does not exist, clear_range
would end up in an infinite while loop.

Introduced by commit 06fda602dbca ("drm/i915: Create page table allocators").

[1] This is already being addressed in one of Mika's patches:
http://mid.gmane.org/1432314314-23530-17-git-send-email-mika.kuoppala@intel.com

Cc: Mika Kuoppala <mika.kuoppala@...ux.intel.com>
Reported-by: John Harrison <john.c.harrison@...el.com>
Signed-off-by: Michel Thierry <michel.thierry@...el.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@...el.com>
Signed-off-by: Jani Nikula <jani.nikula@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/i915/i915_gem_gtt.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -502,17 +502,17 @@ static void gen8_ppgtt_clear_range(struc
 		struct page *page_table;
 
 		if (WARN_ON(!ppgtt->pdp.page_directory[pdpe]))
-			continue;
+			break;
 
 		pd = ppgtt->pdp.page_directory[pdpe];
 
 		if (WARN_ON(!pd->page_table[pde]))
-			continue;
+			break;
 
 		pt = pd->page_table[pde];
 
 		if (WARN_ON(!pt->page))
-			continue;
+			break;
 
 		page_table = pt->page;
 


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