linux-kernel - [PATCH rcu 04/12] rcutorture: Fix memory leak in rcu_test_debug

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Message-Id: <20220620225817.3843106-4-paulmck@kernel.org>
Date:   Mon, 20 Jun 2022 15:58:09 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     rcu@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, kernel-team@...com,
        rostedt@...dmis.org, Zqiang <qiang1.zhang@...el.com>,
        "Paul E . McKenney" <paulmck@...nel.org>
Subject: [PATCH rcu 04/12] rcutorture: Fix memory leak in rcu_test_debug_objects()

From: Zqiang <qiang1.zhang@...el.com>

The kernel memory leak detector located the following:

unreferenced object 0xffff95d941135b50 (size 16):
  comm "swapper/0", pid 1, jiffies 4294667610 (age 1367.451s)
  hex dump (first 16 bytes):
    f0 c6 c2 bd d9 95 ff ff 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000bc81d9b1>] kmem_cache_alloc_trace+0x2f6/0x500
    [<00000000d28be229>] rcu_torture_init+0x1235/0x1354
    [<0000000032c3acd9>] do_one_initcall+0x51/0x210
    [<000000003c117727>] kernel_init_freeable+0x205/0x259
    [<000000003961f965>] kernel_init+0x1a/0x120
    [<000000001998f890>] ret_from_fork+0x22/0x30

This is caused by the rcu_test_debug_objects() function allocating an
rcu_head structure, then failing to free it.  This commit therefore adds
the needed kfree() after the last use of this structure.

Signed-off-by: Zqiang <qiang1.zhang@...el.com>
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
 kernel/rcu/rcutorture.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 9273264772b88..613711b8242b9 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -3116,6 +3116,7 @@ static void rcu_test_debug_objects(void)
 	pr_alert("%s: WARN: Duplicate call_rcu() test complete.\n", KBUILD_MODNAME);
 	destroy_rcu_head_on_stack(&rh1);
 	destroy_rcu_head_on_stack(&rh2);
+	kfree(rhp);
 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
 	pr_alert("%s: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n", KBUILD_MODNAME);
 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
-- 
2.31.1.189.g2e36527f23