On Sun, Oct 18, 2026 at 02:51:18AM +0000, Zqiang wrote: > > > > > > > > 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. > > > > Hi, Joel > > I will resend v2, use DEFINE_PER_CPU() to replace alloc_percpu() to allocate > work_struct objects.
Thank you! Looking forward to it, Joel Fernandes
