nfsd: use kmem_cache_free() instead of kfree()

memory allocated by kmem_cache_alloc() should be freed using
kmem_cache_free(), not kfree().

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Cc: stable@kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4state.c

@@ -364,7 +364,7 @@ kmem_cache *slab)
 		min_stateid = 0;
 	return stid;
 out_free:
-	kfree(stid);
+	kmem_cache_free(slab, stid);
 	return NULL;
 }