drm: Memory fragmentation from lost alignment blocks

If the block needs an alignment but otherwise fits exactly into the tail,
then the split-off block from the start would remain marked as non-free.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
index 7819fd9..a912a0f 100644 (file)
--- a/drivers/gpu/drm/drm_mm.c
+++ b/drivers/gpu/drm/drm_mm.c
@@ -188,36 +188,34 @@ static struct drm_mm_node *drm_mm_split_at_start(struct drm_mm_node *parent,
 
 
 
-struct drm_mm_node *drm_mm_get_block(struct drm_mm_node * parent,
-                               unsigned long size, unsigned alignment)
+struct drm_mm_node *drm_mm_get_block(struct drm_mm_node *node,
+                                    unsigned long size, unsigned alignment)
 {
 
        struct drm_mm_node *align_splitoff = NULL;
-       struct drm_mm_node *child;
        unsigned tmp = 0;
 
        if (alignment)
-               tmp = parent->start % alignment;
+               tmp = node->start % alignment;
 
        if (tmp) {
                align_splitoff =
-                   drm_mm_split_at_start(parent, alignment - tmp, 0);
+                   drm_mm_split_at_start(node, alignment - tmp, 0);
                if (unlikely(align_splitoff == NULL))
                        return NULL;
        }
 
-       if (parent->size == size) {
-               list_del_init(&parent->fl_entry);
-               parent->free = 0;
-               return parent;
+       if (node->size == size) {
+               list_del_init(&node->fl_entry);
+               node->free = 0;
        } else {
-               child = drm_mm_split_at_start(parent, size, 0);
+               node = drm_mm_split_at_start(node, size, 0);
        }
 
        if (align_splitoff)
                drm_mm_put_block(align_splitoff);
 
-       return child;
+       return node;
 }
 
 EXPORT_SYMBOL(drm_mm_get_block);