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

Frederic Weisbecker
2023-12-19T14:08:51Z

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(-)

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2.34.1