--- libmalloc/libmalloc-283.100.6/src/magazine_rack.c
+++ libmalloc/libmalloc-317.40.8/src/magazine_rack.c
@@ -143,10 +143,11 @@
 		rack->region_generation->nextgen->num_regions_allocated = new_size;
 		rack->region_generation->nextgen->num_regions_allocated_shift = new_shift;
 
+		// Ensure everyone sees the advance.
+		OSMemoryBarrier();
+
 		// Throw the switch to atomically advance to the next generation.
 		rack->region_generation = rack->region_generation->nextgen;
-		// Ensure everyone sees the advance.
-		OSMemoryBarrier();
 	}
 
 	// Insert the new region into the hash ring, and update malloc statistics