linux-kernel - [PATCH v2 1/3] testing/radix-tree/maple: Hack around kfree

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Message-ID: <20250812162124.59417-1-pfalcato@suse.de>
Date: Tue, 12 Aug 2025 17:21:22 +0100
From: Pedro Falcato <pfalcato@...e.de>
To: Andrew Morton <akpm@...ux-foundation.org>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	Matthew Wilcox <willy@...radead.org>
Cc: maple-tree@...ts.infradead.org,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Sidhartha Kumar <sidhartha.kumar@...cle.com>,
	Pedro Falcato <pfalcato@...e.de>
Subject: [PATCH v2 1/3] testing/radix-tree/maple: Hack around kfree_rcu not existing

liburcu doesn't have kfree_rcu (or anything similar). Despite that, we
can hack around it in a trivial fashion, by adding a wrapper.

This wrapper only works for maple_nodes, and not anything else (due to
us not being able to know rcu_head offsets in any way), and thus we take
advantage of the type checking to avoid future silent breakage.

Reviewed-by: Sidhartha Kumar <sidhartha.kumar@...cle.com>
Signed-off-by: Pedro Falcato <pfalcato@...e.de>
---
v2:
 - Move kfree_rcu hack to maple-shared.h, to fix userland VMA tests, per
   Lorenzo

 tools/testing/shared/maple-shared.h | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/tools/testing/shared/maple-shared.h b/tools/testing/shared/maple-shared.h
index dc4d30f3860b..572cd2580123 100644
--- a/tools/testing/shared/maple-shared.h
+++ b/tools/testing/shared/maple-shared.h
@@ -9,5 +9,20 @@
 #include <stdlib.h>
 #include <time.h>
 #include "linux/init.h"
+#include <linux/maple_tree.h>
+
+static inline void free_node(struct rcu_head *head)
+{
+	struct maple_node *node = container_of(head, struct maple_node, rcu);
+
+	free(node);
+}
+
+static inline void kfree_rcu_node(struct maple_node *node)
+{
+	call_rcu(&node->rcu, free_node);
+}
+
+#define kfree_rcu(ptr, memb) kfree_rcu_node(ptr)
 
 #endif /* __MAPLE_SHARED_H__ */
-- 
2.50.1