diff --git a/tools/testing/radix-tree/linux.c b/tools/testing/radix-tree/linux.c
index 6903ccf35595f560350a26d03e3eb4369fbb128b..44a0d1ad4408429d67378bf185773f77b3461ab8 100644
--- a/tools/testing/radix-tree/linux.c
+++ b/tools/testing/radix-tree/linux.c
@@ -29,7 +29,7 @@ void *kmem_cache_alloc(struct kmem_cache *cachep, int flags)
 {
 	struct radix_tree_node *node;
 
-	if (flags & __GFP_NOWARN)
+	if (!(flags & __GFP_DIRECT_RECLAIM))
 		return NULL;
 
 	pthread_mutex_lock(&cachep->lock);
@@ -73,10 +73,17 @@ void kmem_cache_free(struct kmem_cache *cachep, void *objp)
 
 void *kmalloc(size_t size, gfp_t gfp)
 {
-	void *ret = malloc(size);
+	void *ret;
+
+	if (!(gfp & __GFP_DIRECT_RECLAIM))
+		return NULL;
+
+	ret = malloc(size);
 	uatomic_inc(&nr_allocated);
 	if (kmalloc_verbose)
 		printf("Allocating %p from malloc\n", ret);
+	if (gfp & __GFP_ZERO)
+		memset(ret, 0, size);
 	return ret;
 }
 
diff --git a/tools/testing/radix-tree/linux/compiler_types.h b/tools/testing/radix-tree/linux/compiler_types.h
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/tools/testing/radix-tree/linux/gfp.h b/tools/testing/radix-tree/linux/gfp.h
index e9fff59dfd8a86cb6022d0dc6e5321a3d9a4f636..e3201ccf54c3c46dc7ffaf9bc6185edd406a6b95 100644
--- a/tools/testing/radix-tree/linux/gfp.h
+++ b/tools/testing/radix-tree/linux/gfp.h
@@ -11,6 +11,7 @@
 #define __GFP_IO		0x40u
 #define __GFP_FS		0x80u
 #define __GFP_NOWARN		0x200u
+#define __GFP_ZERO		0x8000u
 #define __GFP_ATOMIC		0x80000u
 #define __GFP_ACCOUNT		0x100000u
 #define __GFP_DIRECT_RECLAIM	0x400000u
diff --git a/tools/testing/radix-tree/linux/slab.h b/tools/testing/radix-tree/linux/slab.h
index 979baeec7e706aee05ef6bdfbf8dd91494284dd2..a037def0dec637ef9a38b034de5ac1fed4d32d8e 100644
--- a/tools/testing/radix-tree/linux/slab.h
+++ b/tools/testing/radix-tree/linux/slab.h
@@ -3,6 +3,7 @@
 #define SLAB_H
 
 #include <linux/types.h>
+#include <linux/gfp.h>
 
 #define SLAB_HWCACHE_ALIGN 1
 #define SLAB_PANIC 2
@@ -11,6 +12,11 @@
 void *kmalloc(size_t size, gfp_t);
 void kfree(void *);
 
+static inline void *kzalloc(size_t size, gfp_t gfp)
+{
+        return kmalloc(size, gfp | __GFP_ZERO);
+}
+
 void *kmem_cache_alloc(struct kmem_cache *cachep, int flags);
 void kmem_cache_free(struct kmem_cache *cachep, void *objp);