kmemleak: add config to select auto scan

Kmemleak scan can be cpu intensive and can stall user tasks at times.  To
prevent this, add config DEBUG_KMEMLEAK_AUTO_SCAN to enable/disable auto
scan on boot up.  Also protect first_run with DEBUG_KMEMLEAK_AUTO_SCAN as
this is meant for only first automatic scan.

Link: http://lkml.kernel.org/r/1540231723-7087-1-git-send-email-prpatel@nvidia.com
Signed-off-by: Sri Krishna chowdary <schowdary@nvidia.com>
Signed-off-by: Sachin Nikam <snikam@nvidia.com>
Signed-off-by: Prateek <prpatel@nvidia.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 21 insertions, 4 deletions

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index b3c91b9e32f8..2b5a4256e88b 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -593,6 +593,21 @@ config DEBUG_KMEMLEAK_DEFAULT_OFF
           Say Y here to disable kmemleak by default. It can then be enabled
           on the command line via kmemleak=on.
 
+config DEBUG_KMEMLEAK_AUTO_SCAN
+        bool "Enable kmemleak auto scan thread on boot up"
+        default y
+        depends on DEBUG_KMEMLEAK
+        help
+          Depending on the cpu, kmemleak scan may be cpu intensive and can
+          stall user tasks at times. This option enables/disables automatic
+          kmemleak scan at boot up.
+
+          Say N here to disable kmemleak auto scan thread to stop automatic
+          scanning. Disabling this option disables automatic reporting of
+          memory leaks.
+
+          If unsure, say Y.
+
 config DEBUG_STACK_USAGE
         bool "Stack utilization instrumentation"
         depends on DEBUG_KERNEL && !IA64
diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 9c3d2dea0861..f9d9dc250428 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1650,7 +1650,7 @@ static void kmemleak_scan(void)
  */
 static int kmemleak_scan_thread(void *arg)
 {
-        static int first_run = 1;
+        static int first_run = IS_ENABLED(CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN);
 
         pr_info("Automatic memory scanning thread started\n");
         set_user_nice(current, 10);
@@ -2144,9 +2144,11 @@ static int __init kmemleak_late_init(void)
                 return -ENOMEM;
         }
 
-        mutex_lock(&scan_mutex);
-        start_scan_thread();
-        mutex_unlock(&scan_mutex);
+        if (IS_ENABLED(CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN)) {
+                mutex_lock(&scan_mutex);
+                start_scan_thread();
+                mutex_unlock(&scan_mutex);
+        }
 
         pr_info("Kernel memory leak detector initialized\n");