linux-kernel - [PATCH] kmemleak: don't hang if user disables scanning early

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Message-Id: <1468835005-2873-1-git-send-email-vegard.nossum@oracle.com>
Date:	Mon, 18 Jul 2016 11:43:25 +0200
From:	Vegard Nossum <vegard.nossum@...cle.com>
To:	Catalin Marinas <catalin.marinas@....com>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org,
	Vegard Nossum <vegard.nossum@...cle.com>
Subject: [PATCH] kmemleak: don't hang if user disables scanning early

If the user tries to disable automatic scanning early in the boot
process using e.g.:

  echo scan=off > /sys/kernel/debug/kmemleak

then this command will hang until SECS_FIRST_SCAN (= 60) seconds have
elapsed, even though the system is fully initialised.

We can fix this using interruptible sleep and checking if we're
supposed to stop whenever we wake up (like the rest of the code does).

Signed-off-by: Vegard Nossum <vegard.nossum@...cle.com>
---
 mm/kmemleak.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 04320d3..086292f 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1485,8 +1485,10 @@ static int kmemleak_scan_thread(void *arg)
 	 * Wait before the first scan to allow the system to fully initialize.
 	 */
 	if (first_run) {
+		signed long timeout = msecs_to_jiffies(SECS_FIRST_SCAN * 1000);
 		first_run = 0;
-		ssleep(SECS_FIRST_SCAN);
+		while (timeout && !kthread_should_stop())
+			timeout = schedule_timeout_interruptible(timeout);
 	}
 
 	while (!kthread_should_stop()) {
-- 
1.9.1