On 15/01/2018 21:24, Chris Wilson wrote:
If we fail to allocate a new request, make sure we recover the pages
that are in the process of being freed by inserting an RCU barrier.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_gem_request.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
index 72bdc203716f..e6d4857b1f78 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -696,6 +696,9 @@ i915_gem_request_alloc(struct intel_engine_cs *engine,
if (ret)
goto err_unreserve;
+ kmem_cache_shrink(dev_priv->requests);
Hm, the one in idle work handler is not enough? Or from another angle,
the kmem_cache_alloc below won't work hard enough to allocate something
regardless?
+ rcu_barrier();
This one is because req cache is RCU? But doesn't that mean freed
requests are immediately available as per:
static void i915_fence_release(struct dma_fence *fence)
{
struct drm_i915_gem_request *req = to_request(fence);
/* The request is put onto a RCU freelist (i.e. the address
* is immediately reused), mark the fences as being freed now.
* Otherwise the debugobjects for the fences are only marked as
* freed when the slab cache itself is freed, and so we would get
* caught trying to reuse dead objects.
*/
Regards,
Tvrtko
+
req = kmem_cache_alloc(dev_priv->requests, GFP_KERNEL);
if (!req) {
ret = -ENOMEM;
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