linux-kernel - [PATCH] mm: kmemleak: Disable early logging in case of error

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Date:   Wed, 31 Jul 2019 16:23:02 +0100
From:   Catalin Marinas <catalin.marinas@....com>
To:     linux-mm@...ck.org
Cc:     linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Qian Cai <cai@....pw>
Subject: [PATCH] mm: kmemleak: Disable early logging in case of error

If an error occurs during kmemleak_init() (e.g. kmem cache cannot be
created), kmemleak is disabled but kmemleak_early_log remains enabled.
Subsequently, when the .init.text section is freed, the log_early()
function no longer exists. To avoid a page fault in such scenario,
ensure that kmemleak_disable() also disables early logging.

Cc: Andrew Morton <akpm@...ux-foundation.org>
Reported-by: Qian Cai <cai@....pw>
Signed-off-by: Catalin Marinas <catalin.marinas@....com>
---
 mm/kmemleak.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 6e9e8cca663e..f6e602918dac 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1966,6 +1966,7 @@ static void kmemleak_disable(void)
 
 	/* stop any memory operation tracing */
 	kmemleak_enabled = 0;
+	kmemleak_early_log = 0;
 
 	/* check whether it is too early for a kernel thread */
 	if (kmemleak_initialized)
@@ -2009,7 +2010,6 @@ void __init kmemleak_init(void)
 
 #ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
 	if (!kmemleak_skip_disable) {
-		kmemleak_early_log = 0;
 		kmemleak_disable();
 		return;
 	}