[PATCH tip/core/urgent 1/2] rcu: Prevent soft-lockup complaints about no-CBs CPUs

From: Paul E. McKenney
Date: Sat Jan 05 2013 - 11:59:00 EST

From: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>

The wait_event() at the head of the rcu_nocb_kthread() can result in
soft-lockup complaints if the CPU in question does not register RCU
callbacks for an extended period. This commit therefore changes
the wait_event() to a wait_event_interruptible().

Reported-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
kernel/rcutree_plugin.h | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index f6e5ec2..43dba2d 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -2366,10 +2366,11 @@ static int rcu_nocb_kthread(void *arg)
for (;;) {
/* If not polling, wait for next batch of callbacks. */
if (!rcu_nocb_poll)
- wait_event(rdp->nocb_wq, rdp->nocb_head);
+ wait_event_interruptible(rdp->nocb_wq, rdp->nocb_head);
list = ACCESS_ONCE(rdp->nocb_head);
if (!list) {
+ flush_signals(current);


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/