On Tue, Mar 18, 2025 at 10:23:36AM +0100, Frederic Weisbecker wrote:
> When a stall is detected, the state of each NOCB CPU is dumped along
> with the state of each NOCB group. The latter part however is
> incidentally ignored if the NOCB group leader happens not to be
> offloaded itself.
>
> Fix this to make sure related precious informations aren't lost over
> a stall report.
>
> Reported-by: Paul E. McKenney <paul...@kernel.org>
> Signed-off-by: Frederic Weisbecker <frede...@kernel.org>
Much better, thank you!
Reviewed-by: Paul E. McKenney <paul...@kernel.org>
> ---
> kernel/rcu/tree_nocb.h | 3 +++
> kernel/rcu/tree_stall.h | 3 +--
> 2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h
> index 4a954ecf1c36..56baa78c6e85 100644
> --- a/kernel/rcu/tree_nocb.h
> +++ b/kernel/rcu/tree_nocb.h
> @@ -1564,6 +1564,9 @@ static void show_rcu_nocb_state(struct rcu_data *rdp)
> if (rdp->nocb_gp_rdp == rdp)
> show_rcu_nocb_gp_state(rdp);
>
> + if (!rcu_segcblist_is_offloaded(&rdp->cblist))
> + return;
> +
> nocb_next_rdp = list_next_or_null_rcu(&rdp->nocb_gp_rdp->nocb_head_rdp,
> &rdp->nocb_entry_rdp,
> typeof(*rdp),
> diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
> index 56b21219442b..f96235d51642 100644
> --- a/kernel/rcu/tree_stall.h
> +++ b/kernel/rcu/tree_stall.h
> @@ -927,8 +927,7 @@ void show_rcu_gp_kthreads(void)
> for_each_possible_cpu(cpu) {
> rdp = per_cpu_ptr(&rcu_data, cpu);
> cbs += data_race(READ_ONCE(rdp->n_cbs_invoked));
> - if (rcu_segcblist_is_offloaded(&rdp->cblist))
> - show_rcu_nocb_state(rdp);
> + show_rcu_nocb_state(rdp);
> }
> pr_info("RCU callbacks invoked since boot: %lu\n", cbs);
> show_rcu_tasks_gp_kthreads();
> --
> 2.48.1
>
