[0/8,v2] rcu: Fix expedited GP deadlock (and cleanup some nocb stuff)

Message

Frederic Weisbecker Dec. 19, 2023, 2:08 p.m. UTC

TREE04 can trigger a writer stall if run with memory pressure. This
is due to a circular dependency between waiting for expedited grace
period and polling on expedited grace period when workqueues go back
to mayday serialization.

Here is a proposal fix.

Changes since v1:

* Add __maybe_unused to __call_rcu_nocb_wake() declaration (reported by Paul)

* Add reviewed-by tags

* Fix nocb changelog (reported by Neeraj)

* Fixed comment (reported by Hillf)

Frederic Weisbecker (8):
  rcu/nocb: Make IRQs disablement symmetric
  rcu/nocb: Re-arrange call_rcu() NOCB specific code
  rcu/exp: Fix RCU expedited parallel grace period kworker allocation
    failure recovery
  rcu/exp: Handle RCU expedited grace period kworker allocation failure
  rcu: s/boost_kthread_mutex/kthread_mutex
  rcu/exp: Make parallel exp gp kworker per rcu node
  rcu/exp: Handle parallel exp gp kworkers affinity
  rcu/exp: Remove rcu_par_gp_wq

 kernel/rcu/rcu.h         |   5 -
 kernel/rcu/tree.c        | 222 +++++++++++++++++++++++++--------------
 kernel/rcu/tree.h        |  18 ++--
 kernel/rcu/tree_exp.h    |  81 +++-----------
 kernel/rcu/tree_nocb.h   |  38 ++++---
 kernel/rcu/tree_plugin.h |  52 ++-------
 6 files changed, 194 insertions(+), 222 deletions(-)