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

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

From: Steven Rostedt <rost...@goodmis.org>

commit 9297ebf29ad9118edd6c0fedc84f03e35028827d upstream.

The TP_printk() should never dereference any pointers, because the ring
buffer can be read at some unknown time in the future. If a device no
longer exists, it can cause a kernel oops. This also makes this
event useless when saving the ring buffer in userspaces tools such as
perf and trace-cmd.

The i915_gem_evict_vm dereferences the vm pointer which may also not
exist when the ring buffer is read sometime in the future.

Link: 
http://lkml.kernel.org/r/1395095198-20034-3-git-send-email-artag...@gmail.com
Reported-by: Ramkumar Ramachandra <artag...@gmail.com>
Fixes: bcccff847d1f "drm/i915: trace vm eviction instead of everything"
Signed-off-by: Steven Rostedt <rost...@goodmis.org>
[danvet: Try to make it actually compile]
Signed-off-by: Daniel Vetter <daniel.vet...@ffwll.ch>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/gpu/drm/i915/i915_trace.h |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/i915/i915_trace.h
+++ b/drivers/gpu/drm/i915/i915_trace.h
@@ -238,14 +238,16 @@ TRACE_EVENT(i915_gem_evict_vm,
            TP_ARGS(vm),
 
            TP_STRUCT__entry(
+                            __field(u32, dev)
                             __field(struct i915_address_space *, vm)
                            ),
 
            TP_fast_assign(
+                          __entry->dev = vm->dev->primary->index;
                           __entry->vm = vm;
                          ),
 
-           TP_printk("dev=%d, vm=%p", __entry->vm->dev->primary->index, 
__entry->vm)
+           TP_printk("dev=%d, vm=%p", __entry->dev, __entry->vm)
 );
 
 TRACE_EVENT(i915_gem_ring_sync_to,


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