locking/lockdep: Introduce CONFIG_BOOTPARAM_LOCKDEP_CROSSRELEASE_FULLSTACK=y

Add a Kconfig knob that enables the lockdep "crossrelease_fullstack" boot parameter.

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: amir73il@gmail.com
Cc: axboe@kernel.dk
Cc: darrick.wong@oracle.com
Cc: david@fromorbit.com
Cc: hch@infradead.org
Cc: idryomov@gmail.com
Cc: johan@kernel.org
Cc: johannes.berg@intel.com
Cc: kernel-team@lge.com
Cc: linux-block@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-xfs@vger.kernel.org
Cc: oleg@redhat.com
Cc: tj@kernel.org
Link: http://lkml.kernel.org/r/1508921765-15396-7-git-send-email-byungchul.park@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 160b5d6df7cb23201a6cc88dc722006449434d9e..db933d063bfc50354a34f5013ca5619f1508ddf7 100644 (file)
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -76,7 +76,11 @@ module_param(lock_stat, int, 0644);
 #define lock_stat 0
 #endif
 
+#ifdef CONFIG_BOOTPARAM_LOCKDEP_CROSSRELEASE_FULLSTACK
+static int crossrelease_fullstack = 1;
+#else
 static int crossrelease_fullstack;
+#endif
 static int __init allow_crossrelease_fullstack(char *str)
 {
        crossrelease_fullstack = 1;

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index c1e720a22c71304e103ae3eb41db9622b7bc420c..2b439a515c30e06f2181ffde3013b9d372f7739b 100644 (file)
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1179,6 +1179,21 @@ config LOCKDEP_COMPLETIONS
         A deadlock caused by wait_for_completion() and complete() can be
         detected by lockdep using crossrelease feature.
 
+config BOOTPARAM_LOCKDEP_CROSSRELEASE_FULLSTACK
+       bool "Enable the boot parameter, crossrelease_fullstack"
+       depends on LOCKDEP_CROSSRELEASE
+       default n
+       help
+        The lockdep "cross-release" feature needs to record stack traces
+        (of calling functions) for all acquisitions, for eventual later
+        use during analysis. By default only a single caller is recorded,
+        because the unwind operation can be very expensive with deeper
+        stack chains.
+
+        However a boot parameter, crossrelease_fullstack, was
+        introduced since sometimes deeper traces are required for full
+        analysis. This option turns on the boot parameter.
+
 config DEBUG_LOCKDEP
        bool "Lock dependency engine debugging"
        depends on DEBUG_KERNEL && LOCKDEP