[GIT PULL] RCU changes for v6.11

[Paul E. McKenney]

Hello, Linus,

When the merge window opens, please pull this RCU update from:

  git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git tags/rcu.2024.07.12a
  # HEAD: 02219caa92b5b0ed97f8d8b9cf580f6f34a9be31: Merge branches 'doc.2024.06.06a', 'fixes.2024.07.04a', 'mb.2024.06.28a', 'nocb.2024.06.03a', 'rcu-tasks.2024.06.06a', 'rcutorture.2024.06.06a' and 'srcu.2024.06.18a' into HEAD (2024-07-04 13:54:17 -0700)

----------------------------------------------------------------
RCU pull request for v6.11

doc.2024.06.06a: Update Tasks RCU and Tasks Rude RCU description in
	Requirements.rst and clarify rcu_assign_pointer() and
	rcu_dereference() ordering properties.

fixes.2024.07.04a: Add lockdep assertions for RCU readers, limit inline
	wakeups for callback-bypass synchronize_rcu(), add an
	rcutree.nohz_full_patience_delay to reduce nohz_full OS jitter,
	add Uladzislau Rezki as RCU maintainer, and fix a subtle
	callback-migration memory-ordering issue.

mb.2024.06.28a: Remove a number of redundant memory barriers.

nocb.2024.06.03a: Remove unnecessary bypass-list lock-contention
	mitigation, use parking API instead of open-coded ad-hoc
	equivalent, and upgrade obsolete comments.

rcu-tasks.2024.06.06a: Revert avoidance of a deadlock that can no
	longer occur and properly synchronize Tasks Trace RCU checking
	of runqueues.

rcutorture.2024.06.06a: Add tests for handling of double-call_rcu()
	bug, add missing MODULE_DESCRIPTION, and add a script that
	histograms the number of calls to RCU updaters.

srcu.2024.06.18a: Fill out SRCU polled-grace-period API.

----------------------------------------------------------------
Frederic Weisbecker (13):
      rcu/nocb: Fix segcblist state machine comments about bypass
      rcu/nocb: Fix segcblist state machine stale comments about timers
      rcu/nocb: Use kthread parking instead of ad-hoc implementation
      rcu/nocb: Remove buggy bypass lock contention mitigation
      Revert "rcu-tasks: Fix synchronize_rcu_tasks() VS zap_pid_ns_processes()"
      rcu/tasks: Fix stale task snaphot for Tasks Trace
      rcu: Remove full ordering on second EQS snapshot
      rcu: Remove superfluous full memory barrier upon first EQS snapshot
      rcu/exp: Remove superfluous full memory barrier upon first EQS snapshot
      rcu: Remove full memory barrier on boot time eqs sanity check
      rcu: Remove full memory barrier on RCU stall printout
      rcu/exp: Remove redundant full memory barrier at the end of GP
      rcu: Fix rcu_barrier() VS post CPUHP_TEARDOWN_CPU invocation

Jeff Johnson (1):
      rcutorture: Add missing MODULE_DESCRIPTION() macros

Joel Fernandes (Google) (1):
      rcu/tree: Reduce wake up for synchronize_rcu() common case

Oleg Nesterov (1):
      rcu: Eliminate lockless accesses to rcu_sync->gp_count

Paul E. McKenney (13):
      rcu: Add lockdep_assert_in_rcu_read_lock() and friends
      doc: Update Tasks RCU and Tasks Rude RCU description in Requirements.rst
      doc: Clarify rcu_assign_pointer() and rcu_dereference() ordering
      rcutorture: Fix rcu_torture_fwd_cb_cr() data race
      tools/rcu: Add rcu-updaters.sh script
      rcu: Disable interrupts directly in rcu_gp_init()
      srcu: Disable interrupts directly in srcu_gp_end()
      srcu: Add NUM_ACTIVE_SRCU_POLL_OLDSTATE
      srcu: Update cleanup_srcu_struct() comment
      srcu: Fill out polled grace-period APIs
      rcu: Add rcutree.nohz_full_patience_delay to reduce nohz_full OS jitter
      MAINTAINERS: Add Uladzislau Rezki as RCU maintainer
      Merge branches 'doc.2024.06.06a', 'fixes.2024.07.04a', 'mb.2024.06.28a', 'nocb.2024.06.03a', 'rcu-tasks.2024.06.06a', 'rcutorture.2024.06.06a' and 'srcu.2024.06.18a' into HEAD

Zqiang (1):
      rcutorture: Make rcutorture support srcu double call test

 .../Memory-Ordering/Tree-RCU-Memory-Ordering.rst   |   6 +-
 .../RCU/Design/Requirements/Requirements.rst       |  16 +++
 Documentation/RCU/whatisRCU.rst                    |  30 +++--
 Documentation/admin-guide/kernel-parameters.txt    |   8 ++
 MAINTAINERS                                        |   1 +
 include/linux/rcu_segcblist.h                      |  88 ++++++------
 include/linux/rcupdate.h                           |  62 ++++++++-
 include/linux/srcu.h                               |  35 +++++
 kernel/pid_namespace.c                             |  17 ---
 kernel/rcu/rcuscale.c                              |   1 +
 kernel/rcu/rcutorture.c                            |  49 ++++---
 kernel/rcu/refscale.c                              |   1 +
 kernel/rcu/srcutiny.c                              |   3 +-
 kernel/rcu/srcutree.c                              |  13 +-
 kernel/rcu/sync.c                                  |  12 +-
 kernel/rcu/tasks.h                                 |  26 ++--
 kernel/rcu/tree.c                                  |  92 +++++++++----
 kernel/rcu/tree.h                                  |   2 +-
 kernel/rcu/tree_exp.h                              |  24 +++-
 kernel/rcu/tree_nocb.h                             | 147 ++++++---------------
 kernel/rcu/tree_plugin.h                           |  14 +-
 kernel/rcu/tree_stall.h                            |   4 +-
 kernel/sched/core.c                                |  14 +-
 tools/rcu/rcu-updaters.sh                          |  52 ++++++++
 24 files changed, 439 insertions(+), 278 deletions(-)
 create mode 100755 tools/rcu/rcu-updaters.sh