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> Cc: sta...@vger.kernel.org # 3.13+ Fixes: bcccff847d1f "drm/i915: trace vm eviction instead of everything" Signed-off-by: Steven Rostedt <rost...@goodmis.org> --- v2 - fixed build bug. This time tested on a box with an i915. diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h index 6e580c9..783ae08 100644 --- 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, -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
