tree 8cb47b71dc71d38c6f36f698281bf8a05b929393
parent ff3cee39088b1931a432587059d66cd505f785dc
author Paul E. McKenney <paulmck@linux.vnet.ibm.com> 1525814337 -0700
committer Paul E. McKenney <paulmck@linux.vnet.ibm.com> 1531435149 -0700

rcu: Add CPU online/offline state to dump_blkd_tasks()

Interactions between CPU-hotplug operations and grace-period
initialization can result in dump_blkd_tasks().  One of the first
debugging actions in this case is to search back in dmesg to work
out which of the affected rcu_node structure's CPUs are online and to
determine the last CPU-hotplug operation affecting any of those CPUs.
This can be laborious and error-prone, especially when console output
is lost.

This commit therefore causes dump_blkd_tasks() to dump the state of
the affected rcu_node structure's CPUs and the last grace period during
which the last offline and online operation affected each of these CPUs.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>