radix tree test suite: add kmem_cache_set_non_kernel()

kmem_cache_set_non_kernel() is a mechanism to allow a certain number of
kmem_cache_alloc requests to succeed even when GFP_KERNEL is not set in
the flags.  This functionality allows for testing different paths though
the code.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Alexandre Frade <kernel@xanmod.org>

tools/testing/radix-tree/linux.c

@@ -23,15 +23,26 @@ struct kmem_cache {
 	int nr_objs;
 	void *objs;
 	void (*ctor)(void *);
+	unsigned int non_kernel;
 };
 
+void kmem_cache_set_non_kernel(struct kmem_cache *cachep, unsigned int val)
+{
+	cachep->non_kernel = val;
+}
+
 void *kmem_cache_alloc_lru(struct kmem_cache *cachep, struct list_lru *lru,
 		int gfp)
+
 {
 	void *p;
 
-	if (!(gfp & __GFP_DIRECT_RECLAIM))
-		return NULL;
+	if (!(gfp & __GFP_DIRECT_RECLAIM)) {
+		if (!cachep->non_kernel)
+			return NULL;
+
+		cachep->non_kernel--;
+	}
 
 	pthread_mutex_lock(&cachep->lock);
 	if (cachep->nr_objs) {
@@ -90,5 +101,6 @@ kmem_cache_create(const char *name, unsigned int size, unsigned int align,
 	ret->nr_objs = 0;
 	ret->objs = NULL;
 	ret->ctor = ctor;
+	ret->non_kernel = 0;
 	return ret;
 }