On Fri, Feb 04, 2022 at 02:55:07PM -0800, Paul E. McKenney wrote: > Although it is usually safe to invoke synchronize_rcu_expedited() from a > preemption-enabled CPU-hotplug notifier, if it is invoked from a notifier > between CPUHP_AP_RCUTREE_ONLINE and CPUHP_AP_ACTIVE, its attempts to > invoke a workqueue handler will hang due to RCU waiting on a CPU that > the scheduler is not paying attention to. This commit therefore expands > use of the existing workqueue-independent synchronize_rcu_expedited() > from early boot to also include CPUs that are being hotplugged. > > Link: https://lore.kernel.org/lkml/7359f994-8aaf-3cea-f5cf-c0d3929689d6@xxxxxxxxxxx/ > Reported-by: Mukesh Ojha <quic_mojha@xxxxxxxxxxx> > Cc: Tejun Heo <tj@xxxxxxxxxx> > Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> Acked-by: Tejun Heo <tj@xxxxxxxxxx> Thanks. -- tejun
