> On Oct 15, 2026, at 5:46 AM, Zqiang <[email protected]> wrote: > > The RCU Tasks Rude grace period is implemented by invoking the > schedule_on_each_cpu() with an empty work function, which forces > a context switch on every online CPU and guarantees that all > rude-tasks read-side critical sections have completed. However, > schedule_on_each_cpu() can fail (via alloc_percpu() returning > -ENOMEM) and returns immediately, in which case those context > switches never happen, too-short grace period happen. > > This commit therefore wraps the schedule_on_each_cpu() call in > WARN_ONCE() so that this failure is reported as a "Too-short > grace period" warning. > > Signed-off-by: Zqiang <[email protected]> > --- > kernel/rcu/tasks.h | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h > index fcac7361ec51..91c25717402e 100644 > --- a/kernel/rcu/tasks.h > +++ b/kernel/rcu/tasks.h > @@ -1361,7 +1361,8 @@ static void rcu_tasks_be_rude(struct work_struct *work) > static void rcu_tasks_rude_wait_gp(struct rcu_tasks *rtp) > { > rtp->n_ipis += cpumask_weight(cpu_online_mask); > - schedule_on_each_cpu(rcu_tasks_be_rude); > + WARN_ONCE(schedule_on_each_cpu(rcu_tasks_be_rude), > + "%s: Too-short grace period, OOM is now expected behavior!!!\n", > rtp->name);
Is that the best error message? OOM is expected when grace periods do not conclude. Thanks. > } > > static void call_rcu_tasks_rude(struct rcu_head *rhp, rcu_callback_t func); > -- > 2.17.1 >
