[Intel-gfx] PROBLEM: i915 causes complete desktop freezes in 4.15-rc5

[Chris Wilson]

Quoting Alexandru Chirvasitu (2018-01-05 22:05:18)
> Here we go.
> 
> I have
> 
> CONFIG_PAGE_POISONING not set
> CONFIG_SLUB_STATS=y
> CONFIG_SLUB_DEBUG not set
> CONFIG_KASAN=y
> 
> .config attached along as well for verification, in case I missed
> anything.
> 
> Again crashed by an attempt to open a terminal window.

Gotcha,

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index b21322b50419..96cf46a10b4e 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -472,7 +472,7 @@ static void __fence_set_priority(struct dma_fence *fence, int prio)
        struct drm_i915_gem_request *rq;
        struct intel_engine_cs *engine;
 
-       if (!dma_fence_is_i915(fence))
+       if (dma_fence_is_signaled(fence) || !dma_fence_is_i915(fence))
                return;
 
        rq = to_request(fence);