linux-kernel - [PATCH v2 7/7] kunit, slub: add test_kfree_rcu() and test_leak

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Message-Id: <20240807-b4-slab-kfree_rcu-destroy-v2-7-ea79102f428c@suse.cz>
Date: Wed, 07 Aug 2024 12:31:20 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: "Paul E. McKenney" <paulmck@...nel.org>, 
 Joel Fernandes <joel@...lfernandes.org>, 
 Josh Triplett <josh@...htriplett.org>, Boqun Feng <boqun.feng@...il.com>, 
 Christoph Lameter <cl@...ux.com>, David Rientjes <rientjes@...gle.com>
Cc: Steven Rostedt <rostedt@...dmis.org>, 
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, 
 Lai Jiangshan <jiangshanlai@...il.com>, Zqiang <qiang.zhang1211@...il.com>, 
 Julia Lawall <Julia.Lawall@...ia.fr>, Jakub Kicinski <kuba@...nel.org>, 
 "Jason A. Donenfeld" <Jason@...c4.com>, 
 "Uladzislau Rezki (Sony)" <urezki@...il.com>, 
 Andrew Morton <akpm@...ux-foundation.org>, 
 Roman Gushchin <roman.gushchin@...ux.dev>, 
 Hyeonggon Yoo <42.hyeyoo@...il.com>, linux-mm@...ck.org, 
 linux-kernel@...r.kernel.org, rcu@...r.kernel.org, 
 Alexander Potapenko <glider@...gle.com>, Marco Elver <elver@...gle.com>, 
 Dmitry Vyukov <dvyukov@...gle.com>, kasan-dev@...glegroups.com, 
 Jann Horn <jannh@...gle.com>, Mateusz Guzik <mjguzik@...il.com>, 
 Vlastimil Babka <vbabka@...e.cz>
Subject: [PATCH v2 7/7] kunit, slub: add test_kfree_rcu() and
 test_leak_destroy()

Add a test that will create cache, allocate one object, kfree_rcu() it
and attempt to destroy it. As long as the usage of kvfree_rcu_barrier()
in kmem_cache_destroy() works correctly, there should be no warnings in
dmesg and the test should pass.

Additionally add a test_leak_destroy() test that leaks an object on
purpose and verifies that kmem_cache_destroy() catches it.

Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
---
 lib/slub_kunit.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/lib/slub_kunit.c b/lib/slub_kunit.c
index e6667a28c014..6e3a1e5a7142 100644
--- a/lib/slub_kunit.c
+++ b/lib/slub_kunit.c
@@ -5,6 +5,7 @@
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/kernel.h>
+#include <linux/rcupdate.h>
 #include "../mm/slab.h"

 static struct kunit_resource resource;
@@ -157,6 +158,34 @@ static void test_kmalloc_redzone_access(struct kunit *test)
 	kmem_cache_destroy(s);
 }

+struct test_kfree_rcu_struct {
+	struct rcu_head rcu;
+};
+
+static void test_kfree_rcu(struct kunit *test)
+{
+	struct kmem_cache *s = test_kmem_cache_create("TestSlub_kfree_rcu",
+				sizeof(struct test_kfree_rcu_struct),
+				SLAB_NO_MERGE);
+	struct test_kfree_rcu_struct *p = kmem_cache_alloc(s, GFP_KERNEL);
+
+	kfree_rcu(p, rcu);
+	kmem_cache_destroy(s);
+
+	KUNIT_EXPECT_EQ(test, 0, slab_errors);
+}
+
+static void test_leak_destroy(struct kunit *test)
+{
+	struct kmem_cache *s = test_kmem_cache_create("TestSlub_kfree_rcu",
+							64, SLAB_NO_MERGE);
+	kmem_cache_alloc(s, GFP_KERNEL);
+
+	kmem_cache_destroy(s);
+
+	KUNIT_EXPECT_EQ(test, 1, slab_errors);
+}
+
 static int test_init(struct kunit *test)
 {
 	slab_errors = 0;
@@ -177,6 +206,8 @@ static struct kunit_case test_cases[] = {

 	KUNIT_CASE(test_clobber_redzone_free),
 	KUNIT_CASE(test_kmalloc_redzone_access),
+	KUNIT_CASE(test_kfree_rcu),
+	KUNIT_CASE(test_leak_destroy),
 	{}
 };

-- 
2.46.0