From: Paul E. McKenney Date: Thu, 22 Jan 2015 22:32:06 +0000 (-0800) Subject: rcu: Detect stalls caused by failure to propagate up rcu_node tree X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=237a0f2193c6daf9b1edd7fd15d55e680f268952;p=linux-beck.git rcu: Detect stalls caused by failure to propagate up rcu_node tree If all CPUs have passed through quiescent states, then stalls might be due to starvation of the grace-period kthread or to failure to propagate the quiescent states up the rcu_node combining tree. The current stall warning messages do not differentiate, so this commit adds a printout of the root rcu_node structure's ->qsmask field. Signed-off-by: Paul E. McKenney --- diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 98da632d1d49..3b7e4133ca99 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1196,9 +1196,10 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum) } else { j = jiffies; gpa = ACCESS_ONCE(rsp->gp_activity); - pr_err("All QSes seen, last %s kthread activity %ld (%ld-%ld), jiffies_till_next_fqs=%ld\n", + pr_err("All QSes seen, last %s kthread activity %ld (%ld-%ld), jiffies_till_next_fqs=%ld, root ->qsmask %#lx\n", rsp->name, j - gpa, j, gpa, - jiffies_till_next_fqs); + jiffies_till_next_fqs, + rcu_get_root(rsp)->qsmask); /* In this case, the current CPU might be at fault. */ sched_show_task(current); }