1 files changed, 21 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index d6a994a07393..26d08bb58218 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -539,6 +539,8 @@ i915_gem_execbuffer_relocate_slow(struct drm_device *dev,
         total = 0;
         for (i = 0; i < count; i++) {
                 struct drm_i915_gem_relocation_entry __user *user_relocs;
+                u64 invalid_offset = (u64)-1;
+                int j;
 
                 user_relocs = (void __user *)(uintptr_t)exec[i].relocs_ptr;
 
@@ -549,6 +551,25 @@ i915_gem_execbuffer_relocate_slow(struct drm_device *dev,
                         goto err;
                 }
 
+                /* As we do not update the known relocation offsets after
+                 * relocating (due to the complexities in lock handling),
+                 * we need to mark them as invalid now so that we force the
+                 * relocation processing next time. Just in case the target
+                 * object is evicted and then rebound into its old
+                 * presumed_offset before the next execbuffer - if that
+                 * happened we would make the mistake of assuming that the
+                 * relocations were valid.
+                 */
+                for (j = 0; j < exec[i].relocation_count; j++) {
+                        if (copy_to_user(&user_relocs[j].presumed_offset,
+                                         &invalid_offset,
+                                         sizeof(invalid_offset))) {
+                                ret = -EFAULT;
+                                mutex_lock(&dev->struct_mutex);
+                                goto err;
+                        }
+                }
+
                 reloc_offset[i] = total;
                 total += exec[i].relocation_count;
         }