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From:   Jim Cromie <jim.cromie@gmail.com>
To:     catalin.marinas@arm.com, linux-mm@kvack.org
Cc:     linux-kernel@vger.kernel.org, Jim Cromie <jim.cromie@gmail.com>
Subject: [PATCH 3/3] kmemleak-test: drop __init to get better backtrace
Date:   Tue, 25 Apr 2023 16:24:46 -0600
Message-Id: <20230425222446.170486-4-jim.cromie@gmail.com>
In-Reply-To: <20230425222446.170486-1-jim.cromie@gmail.com>
References: <20230425222446.170486-1-jim.cromie@gmail.com>
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Drop the __init on kmemleak_test_init().  With it, the storage is
reclaimed, but then the symbol isn't available for "%pS" rendering,
and the backtrace gets a bare pointer where the actual leak happened.

unreferenced object 0xffff88800a2b0800 (size 1024):
  comm "modprobe", pid 413, jiffies 4294953430
  hex dump (first 32 bytes):
    73 02 00 00 75 01 00 68 02 00 00 01 00 00 00 04  s...u..h........
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace (ck 603070071):
    [<00000000fabad728>] kmalloc_trace+0x26/0x90
    [<00000000ef738764>] 0xffffffffc02350a2
    [<00000000004e5795>] do_one_initcall+0x43/0x210
    [<00000000d768905e>] do_init_module+0x4a/0x210
    [<0000000087135ab5>] __do_sys_finit_module+0x93/0xf0
    [<000000004fcb1fa2>] do_syscall_64+0x34/0x80
    [<00000000c73c8d9d>] entry_SYSCALL_64_after_hwframe+0x46/0xb0

with __init gone, that trace entry renders like:

    [<00000000ef738764>] kmemleak_test_init+<offset>/<size>
---
 samples/kmemleak/kmemleak-test.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/samples/kmemleak/kmemleak-test.c b/samples/kmemleak/kmemleak-test.c
index 7b476eb8285f..6ced5ddd99d4 100644
--- a/samples/kmemleak/kmemleak-test.c
+++ b/samples/kmemleak/kmemleak-test.c
@@ -32,7 +32,7 @@ static DEFINE_PER_CPU(void *, kmemleak_test_pointer);
  * Some very simple testing. This function needs to be extended for
  * proper testing.
  */
-static int __init kmemleak_test_init(void)
+static int kmemleak_test_init(void)
 {
 	struct test_node *elem;
 	int i;
-- 
2.40.0