Hello!

This series contains updates to RCU expedited grace periods, most
notably providing milliseconds-scale soft real-time response from
synchronize_rcu_expedited().  This is also the first time in almost
30 years of RCU that someone other than me has pushed for a reduction
in the RCU CPU stall-warning timeout, in this case by more than three
orders of magnitude from 21 seconds to 20 milliseconds.  This tighter
timeout applies only to expedited grace periods.

1.	Introduce CONFIG_RCU_EXP_CPU_STALL_TIMEOUT, courtesy of Uladzislau
	Rezki.

2.	Move expedited grace period (GP) work to RT kthread_worker,
	courtesy of Kalesh Singh.

						Thanx, Paul

------------------------------------------------------------------------

 b/Documentation/RCU/stallwarn.rst                 |   18 ++
 b/Documentation/admin-guide/kernel-parameters.txt |    9 +
 b/kernel/rcu/Kconfig                              |   14 ++
 b/kernel/rcu/Kconfig.debug                        |   13 +
 b/kernel/rcu/rcu.h                                |    2 
 b/kernel/rcu/tree.c                               |   51 +++++++
 b/kernel/rcu/tree.h                               |    5 
 b/kernel/rcu/tree_exp.h                           |    4 
 b/kernel/rcu/tree_stall.h                         |   26 +++
 b/kernel/rcu/update.c                             |    2 
 kernel/rcu/rcu.h                                  |    5 
 kernel/rcu/tree_exp.h                             |  147 +++++++++++++++++-----
 12 files changed, 260 insertions(+), 36 deletions(-)