SLUB: do proper locking during dma slab creation
We modify the kmalloc_cache_dma[] array without proper locking. Do the proper
locking and undo the dma cache creation if another processor has already
created it.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/slub.c b/mm/slub.c
index 2b50b97..f93adb9 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2301,8 +2301,15 @@
text = kasprintf(flags & ~SLUB_DMA, "kmalloc_dma-%d",
(unsigned int)realsize);
s = create_kmalloc_cache(x, text, realsize, flags);
- kmalloc_caches_dma[index] = s;
- return s;
+ down_write(&slub_lock);
+ if (!kmalloc_caches_dma[index]) {
+ kmalloc_caches_dma[index] = s;
+ up_write(&slub_lock);
+ return s;
+ }
+ up_write(&slub_lock);
+ kmem_cache_destroy(s);
+ return kmalloc_caches_dma[index];
}
#endif