rcu: Add RCU_CPU_STALL_VERBOSE to dump detailed per-task information

When RCU detects a grace-period stall, it currently just prints
out the PID of any tasks doing the stalling.  This patch adds
RCU_CPU_STALL_VERBOSE, which enables the more-verbose reporting
from sched_show_task().

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1266887105-1528-21-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 12 insertions, 0 deletions

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 6af20a8a0a54..4cdab452bfe2 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -781,6 +781,18 @@ config RCU_CPU_STALL_DETECTOR
 
           Say Y if you are unsure.
 
+config RCU_CPU_STALL_VERBOSE
+        bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
+        depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
+        default n
+        help
+          This option causes RCU to printk detailed per-task information
+          for any tasks that are stalling the current RCU grace period.
+
+          Say N if you are unsure.
+
+          Say Y if you want to enable such checks.
+
 config KPROBES_SANITY_TEST
         bool "Kprobes sanity tests"
         depends on DEBUG_KERNEL