* Liu Song <liusong@xxxxxxxxxxxxxxxxx> wrote:
From: Liu Song <liusong@xxxxxxxxxxxxxxxxx>^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
If the number of CPUs is large, "sysrq_sched_debug_show" will execute for
a long time. Every time I execute "echo t > /proc/sysrq-trigger" on my
128-core machine, the rcu stall warning will be triggered. Moreover,
sysrq_sched_debug_show does not need to be protected by rcu_read_lock,
and no rcu stall warning will appear after adjustment.That doesn't mean it doesn't have to be protected by *any* lock - which
your patch implements AFAICS.
There's a couple of lines such as:
for_each_online_cpu(cpu) {
... which need to be protected against CPU hotplug events.
I haven't checked any of the deeper code to see what RCU or other
protection it may need, but clearly you didn't either ...
Thanks,
Ingo