Broken locking in ttm_bo_swapout

Matthew Bullock matthew.bullock at
Thu Jan 20 10:53:16 PST 2011

I have a fairly simple opengl application running on nouveau. It 
effectively just plots a couple of very large images that change regularly.

I've been getting an easily repeatable failure, hitting the
BUG_ON(in_interrupt) in vfree() that is called during ttm_shrink_work().
Obviously vfree() is being called with a lock held...

Looking at the locking up through the stack trace, there's an obvious 

There should be a:
before the continue in ttm_bo_swapout() in drivers/gpu/drm/ttm/ttm_bo.c

--- ttm_bo.c~   2011-01-05 00:50:19.000000000 +0000
+++ ttm_bo.c    2011-01-20 18:11:57.262813765 +0000
@@ -1761,6 +1761,7 @@ static int ttm_bo_swapout(struct ttm_mem
                         (void) ttm_bo_cleanup_refs(bo, false, false, 
                         kref_put(&bo->list_kref, ttm_bo_release_list);
+                       spin_lock(&glob->lru_lock);

That fixes the problem for me.


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