Patch "drm/vmwgfx: Fix execbuf locking issues" has been added to the 3.14-stable tree

This is a note to let you know that I've just added the patch titled

drm/vmwgfx: Fix execbuf locking issues

to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
drm-vmwgfx-fix-execbuf-locking-issues.patch
and it can be found in the queue-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Thomas Hellstrom <[email protected]>
Date: Tue, 11 Aug 2015 22:31:17 -0700
Subject: drm/vmwgfx: Fix execbuf locking issues

From: Thomas Hellstrom <[email protected]>

commit 3e04e2fe6d87807d27521ad6ebb9e7919d628f25 upstream.

This addresses two issues that cause problems with viewperf maya-03 in situation with memory pressure.

The first issue causes attempts to unreserve buffers if batched reservation fails due to, for example, a signal pending. While previously the ttm_eu api was resistant against this type of error, it is no longer and the lockdep code will complain about attempting to unreserve buffers that are not reserved. The issue is resolved by avoid calling ttm_eu_backoff_reservation in the buffer reserve error path.

The second issue is that the binding_mutex may be held when user-space fence objects are created and hence during memory reclaims. This may cause recursive attempts to grab the binding mutex. The issue is resolved by not holding the binding mutex across fence creation and submission.

---
 drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

@@ -2475,7 +2475,7 @@ int vmw_execbuf_process(struct drm_file
 
 	ret = vmw_resources_validate(sw_context);
 	if (unlikely(ret != 0))
-		goto out_err;
+		goto out_err_nores;
 
 	if (throttle_us) {
 		ret = vmw_wait_lag(dev_priv, &dev_priv->fifo.marker_queue,

@@ -2511,6 +2511,7 @@ int vmw_execbuf_process(struct drm_file
 	vmw_resource_relocations_free(&sw_context->res_relocations);
 
 	vmw_fifo_commit(dev_priv, command_size);
+	mutex_unlock(&dev_priv->binding_mutex);
 
 	vmw_query_bo_switch_commit(dev_priv, sw_context);
 	ret = vmw_execbuf_fence_commands(file_priv, dev_priv,

@@ -2526,7 +2527,6 @@ int vmw_execbuf_process(struct drm_file
 		DRM_ERROR("Fence submission error. Syncing.\n");
 
 	vmw_resource_list_unreserve(&sw_context->resource_list, false);
-	mutex_unlock(&dev_priv->binding_mutex);
 
 	ttm_eu_fence_buffer_objects(&ticket, &sw_context->validate_nodes,
 				    (void *) fence);

Patches currently in stable-queue which might be from [email protected] are

queue-3.14/drm-vmwgfx-fix-execbuf-locking-issues.patch