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, 4 insertions, 0 deletions

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index b07be37d2aa..525d3981061 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -489,6 +489,10 @@ static void print_other_cpu_stall(struct rcu_state *rsp)
                smp_processor_id(), (long)(jiffies - rsp->gp_start));
         trigger_all_cpu_backtrace();
 
+        /* If so configured, complain about tasks blocking the grace period. */
+
+        rcu_print_detail_task_stall(rsp);
+
         force_quiescent_state(rsp, 0);  /* Kick them all. */
 }