lib/generic-radix-tree.c: Make nodes more reasonably sized

this code originally used the page allocator directly, but most code
shouldn't do that - PAGE_SIZE varies with architecture, and slab is
faster.

4k is also on the large side for typical usage, 512 bytes is a better
choice for typical usage that might be somewhat sparse.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

1 files changed, 12 insertions, 23 deletions

diff --git a/lib/generic-radix-tree.c b/lib/generic-radix-tree.c
index 41f1bcdc4488..aaefb9b678c8 100644
--- a/lib/generic-radix-tree.c
+++ b/lib/generic-radix-tree.c
@@ -5,7 +5,7 @@
 #include <linux/gfp.h>
 #include <linux/kmemleak.h>
 
-#define GENRADIX_ARY		(PAGE_SIZE / sizeof(struct genradix_node *))
+#define GENRADIX_ARY		(GENRADIX_NODE_SIZE / sizeof(struct genradix_node *))
 #define GENRADIX_ARY_SHIFT	ilog2(GENRADIX_ARY)
 
 struct genradix_node {
@@ -14,13 +14,13 @@ struct genradix_node {
 		struct genradix_node	*children[GENRADIX_ARY];
 
 		/* Leaf: */
-		u8			data[PAGE_SIZE];
+		u8			data[GENRADIX_NODE_SIZE];
 	};
 };
 
 static inline int genradix_depth_shift(unsigned depth)
 {
-	return PAGE_SHIFT + GENRADIX_ARY_SHIFT * depth;
+	return GENRADIX_NODE_SHIFT + GENRADIX_ARY_SHIFT * depth;
 }
 
 /*
@@ -33,7 +33,7 @@ static inline size_t genradix_depth_size(unsigned depth)
 
 /* depth that's needed for a genradix that can address up to ULONG_MAX: */
 #define GENRADIX_MAX_DEPTH	\
-	DIV_ROUND_UP(BITS_PER_LONG - PAGE_SHIFT, GENRADIX_ARY_SHIFT)
+	DIV_ROUND_UP(BITS_PER_LONG - GENRADIX_NODE_SHIFT, GENRADIX_ARY_SHIFT)
 
 #define GENRADIX_DEPTH_MASK				\
 	((unsigned long) (roundup_pow_of_two(GENRADIX_MAX_DEPTH + 1) - 1))
@@ -79,23 +79,12 @@ EXPORT_SYMBOL(__genradix_ptr);
 
 static inline struct genradix_node *genradix_alloc_node(gfp_t gfp_mask)
 {
-	struct genradix_node *node;
-
-	node = (struct genradix_node *)__get_free_page(gfp_mask|__GFP_ZERO);
-
-	/*
-	 * We're using pages (not slab allocations) directly for kernel data
-	 * structures, so we need to explicitly inform kmemleak of them in order
-	 * to avoid false positive memory leak reports.
-	 */
-	kmemleak_alloc(node, PAGE_SIZE, 1, gfp_mask);
-	return node;
+	return kzalloc(GENRADIX_NODE_SIZE, gfp_mask);
 }
 
 static inline void genradix_free_node(struct genradix_node *node)
 {
-	kmemleak_free(node);
-	free_page((unsigned long)node);
+	kfree(node);
 }
 
 /*
@@ -200,7 +189,7 @@ restart:
 			i++;
 			iter->offset = round_down(iter->offset + objs_per_ptr,
 						  objs_per_ptr);
-			iter->pos = (iter->offset >> PAGE_SHIFT) *
+			iter->pos = (iter->offset >> GENRADIX_NODE_SHIFT) *
 				objs_per_page;
 			if (i == GENRADIX_ARY)
 				goto restart;
@@ -209,7 +198,7 @@ restart:
 		n = n->children[i];
 	}
 
-	return &n->data[iter->offset & (PAGE_SIZE - 1)];
+	return &n->data[iter->offset & (GENRADIX_NODE_SIZE - 1)];
 }
 EXPORT_SYMBOL(__genradix_iter_peek);
 
@@ -235,7 +224,7 @@ restart:
 
 	if (ilog2(iter->offset) >= genradix_depth_shift(level)) {
 		iter->offset = genradix_depth_size(level);
-		iter->pos = (iter->offset >> PAGE_SHIFT) * objs_per_page;
+		iter->pos = (iter->offset >> GENRADIX_NODE_SHIFT) * objs_per_page;
 
 		iter->offset -= obj_size_plus_page_remainder;
 		iter->pos--;
@@ -251,7 +240,7 @@ restart:
 			size_t objs_per_ptr = genradix_depth_size(level);
 
 			iter->offset = round_down(iter->offset, objs_per_ptr);
-			iter->pos = (iter->offset >> PAGE_SHIFT) * objs_per_page;
+			iter->pos = (iter->offset >> GENRADIX_NODE_SHIFT) * objs_per_page;
 
 			if (!iter->offset)
 				return NULL;
@@ -267,7 +256,7 @@ restart:
 		n = n->children[i];
 	}
 
-	return &n->data[iter->offset & (PAGE_SIZE - 1)];
+	return &n->data[iter->offset & (GENRADIX_NODE_SIZE - 1)];
 }
 EXPORT_SYMBOL(__genradix_iter_peek_prev);
 
@@ -289,7 +278,7 @@ int __genradix_prealloc(struct __genradix *radix, size_t size,
 {
 	size_t offset;
 
-	for (offset = 0; offset < size; offset += PAGE_SIZE)
+	for (offset = 0; offset < size; offset += GENRADIX_NODE_SIZE)
 		if (!__genradix_ptr_alloc(radix, offset, gfp_mask))
 			return -ENOMEM;