rcu: Add ->gp_max to show_rcu_gp_kthreads() output

This commit adds ->gp_max to show_rcu_gp_kthreads() output in order to
better diagnose RCU priority boosting failures.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index fb4702570316e390beb31ab1aaa57a5f881a52e6..a4e2bb3bdce73c93e7691a88dae636c3833c31a0 100644 (file)
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -737,12 +737,13 @@ void show_rcu_gp_kthreads(void)
        jr = j - data_race(rcu_state.gp_req_activity);
        js = j - data_race(rcu_state.gp_start);
        jw = j - data_race(rcu_state.gp_wake_time);
-       pr_info("%s: wait state: %s(%d) ->state: %#lx ->rt_priority %u delta ->gp_start %lu ->gp_activity %lu ->gp_req_activity %lu ->gp_wake_time %lu ->gp_wake_seq %ld ->gp_seq %ld ->gp_seq_needed %ld ->gp_flags %#x\n",
+       pr_info("%s: wait state: %s(%d) ->state: %#lx ->rt_priority %u delta ->gp_start %lu ->gp_activity %lu ->gp_req_activity %lu ->gp_wake_time %lu ->gp_wake_seq %ld ->gp_seq %ld ->gp_seq_needed %ld ->gp_max %lu ->gp_flags %#x\n",
                rcu_state.name, gp_state_getname(rcu_state.gp_state),
                rcu_state.gp_state, t ? t->state : 0x1ffffL, t ? t->rt_priority : 0xffU,
                js, ja, jr, jw, (long)data_race(rcu_state.gp_wake_seq),
                (long)data_race(rcu_state.gp_seq),
                (long)data_race(rcu_get_root()->gp_seq_needed),
+               data_race(rcu_state.gp_max),
                data_race(rcu_state.gp_flags));
        rcu_for_each_node_breadth_first(rnp) {
                if (ULONG_CMP_GE(READ_ONCE(rcu_state.gp_seq),