From b15805013b441b13fcf6e402c03421c03edb79c6 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 7 Apr 2021 15:14:01 -0700 Subject: [PATCH] rcu: Make show_rcu_gp_kthreads() dump rcu_node structures blocking GP Currently, show_rcu_gp_kthreads() only dumps rcu_node structures that have outdated ideas of the current grace-period number. This commit also dumps those that are in any way blocking the current grace period. This helps diagnose RCU priority boosting failures. Signed-off-by: Paul E. McKenney --- kernel/rcu/tree_stall.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index c1f83864a18e..e6bd518e0bc4 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -746,8 +746,9 @@ void show_rcu_gp_kthreads(void) 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), - READ_ONCE(rnp->gp_seq_needed))) + if (ULONG_CMP_GE(READ_ONCE(rcu_state.gp_seq), READ_ONCE(rnp->gp_seq_needed)) && + !data_race(rnp->qsmask) && !data_race(rnp->boost_tasks) && + !data_race(rnp->exp_tasks) && !data_race(rnp->gp_tasks)) continue; pr_info("\trcu_node %d:%d ->gp_seq %ld ->gp_seq_needed %ld ->qsmask %#lx %c%c%c%c ->n_boosts %ld\n", rnp->grplo, rnp->grphi, -- 2.20.1