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Commit 237a0f21 authored by Paul E. McKenney's avatar Paul E. McKenney
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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: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 18c629ea

kernel/rcu/tree.c

+3 −2
Original line number Diff line number Diff line
@@ -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);

		}