[GIT PULL rcu/next] RCU commits for 4.19

From: Paul E. McKenney
Date: Mon Jul 16 2018 - 13:49:15 EST

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Hello, Ingo!

This pull request contains the following changes:

1. An optimization and a fix for RCU expedited grace periods, with
the fix being from Boqun Feng.

http://lkml.kernel.org/r/20180625224308.GA10064@xxxxxxxxxxxxxxxxxx

2. Miscellaneous fixes, including a lockdep-annotation fix from
Boqun Feng.

http://lkml.kernel.org/r/20180625230410.GA13250@xxxxxxxxxxxxxxxxxx

3. SRCU updates.

http://lkml.kernel.org/r/20180625224734.GA10860@xxxxxxxxxxxxxxxxxx

4. Updates to rcutorture and associated scripting.

http://lkml.kernel.org/r/20180625225735.GA11793@xxxxxxxxxxxxxxxxxx

5. Introduce grace-period sequence numbers to the RCU-bh, RCU-preempt,
and RCU-sched flavors, replacing the old ->gpnum and ->completed
pair of fields. This change allows lockless code to obtain the
complete grace-period state with a single READ_ONCE(), which is
needed to maintain tolerable lock contention during the upcoming
consolidation of the three RCU flavors. Note that grace-period
sequence numbers are already used by rcu_barrier(), expedited
RCU grace periods, and SRCU, and are thus already heavily used
and well-tested. Joel Fernandes contributed a number of excellent
fixes and improvements.

http://lkml.kernel.org/r/20180626000841.GA15696@xxxxxxxxxxxxxxxxxx

6. Clean up some grace-period-reporting loose ends, including
improving the handling of quiescent states from offline CPUs
and fixing some false-positive WARN_ON_ONCE() invocations.
(Strictly speaking, the WARN_ON_ONCE() invocations were quite
correct, but their invariants were (harmlessly) violated by the
earlier sloppy handling of quiescent states from offline CPUs.)
In addition, improve grace-period forward-progress guarantees so
as to allow removal of fail-safe checks that required otherwise
needless lock acquisitions. Finally, add more diagnostics to
help debug the upcoming consolidation of the RCU-bh, RCU-preempt,
and RCU-sched flavors.

http://lkml.kernel.org/r/20180626002052.GA24146@xxxxxxxxxxxxxxxxxx

7. Additional miscellaneous fixes, including those contributed by
Byungchul Park, Mauro Carvalho Chehab, Joe Perches, Joel Fernandes,
Steven Rostedt, Andrea Parri, and Neil Brown.

http://lkml.kernel.org/r/20180626003448.GA26209@xxxxxxxxxxxxxxxxxx

8. Additional torture-test changes, including several contributed by
Arnd Bergmann and Joel Fernandes.

http://lkml.kernel.org/r/20180626005205.GA28179@xxxxxxxxxxxxxxxxxx

The layout of this pull request is unusual due to the large footprint
of the commits in #5 and #6. Therefore #1-#4 are branches on top of
v4.18-rc1, #5 and #6 are stacked on top of each other based off of the
merge point for #1-#4, and #7 and #8 are branches on top of #6.

Although I merged this series with v4.18-rc4 without conflicts and tested
the results, Stephen Rothwell has reported a couple of conflicts with
this series in the course of his -next integration-testing efforts and
has provided the following resolutions:

http://lkml.kernel.org/r/20180514134636.61831bcc@xxxxxxxxxxxxxxxx
http://lkml.kernel.org/r/20180622122717.5f475829@xxxxxxxxxxxxxxxx

Both of these resolutions look good to me.

This pull request increases the size of RCU by not quite 500 lines.
Of this, about 200 is due to adding test code to rcutorture in
order to adequately test the consolidated RCU-bh, RCU-preempt, and
RCU-sched flavors. The purpose of adding this test code early is to
test it against RCU-sched, which happens to already support compound RCU
read-side critical sections via rcu_read_lock_sched(), preempt_disable(),
local_bh_disable(), and local_irq_save(). The remainder are primarily
due to the addition of diagnostics and the fixing of quiescent-state and
grace-period reporting. This size increase is temporary: The overall
effect of this set of cleanups, the consolidation of the three RCU
flavors, and additional cleanups will be to -decrease- RCU's line count
by a couple of hundred lines.

All of these changes have been subjected to 0day Test Robot and -next
testing, and are available in the git repository at:

git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git for-mingo

for you to fetch changes up to 18952651dae8efcc6d565c97f8fe5629b399cb3e:

Merge branches 'fixes1.2018.07.12b' and 'torture1.2018.07.12b' into HEAD (2018-07-12 15:42:41 -0700)

----------------------------------------------------------------
Andrea Parri (1):
doc: Update synchronize_rcu() definition in whatisRCU.txt

Arnd Bergmann (1):
rcutorture: Use monotonic timestamp for stall detection

Boqun Feng (2):
rcu: Use the proper lockdep annotation in dump_blkd_tasks()
rcu: Make expedited GPs handle CPU 0 being offline

Byungchul Park (2):
rcu: Improve rcu_note_voluntary_context_switch() reporting
rcu: Check the range of jiffies_till_{first,next}_fqs when setting them

Joe Perches (1):
rcu: Use pr_fmt to prefix "rcu: " to logging output

Joel Fernandes (1):
rcu: Rename the grace-period-request variables and parameters

Joel Fernandes (Google) (10):
rcu: Produce last "CleanupMore" trace only if late-breaking request
rcu: Fix cpustart tracepoint gp_seq number
rcu: Use better variable names in funnel locking loop
rcu: Identify grace period is in progress as we advance up the tree
rcu: Add comment documenting how rcu_seq_snap works
rcu: Assign higher prio to RCU threads if rcutorture is built-in
rcutorture: Disable RT throttling for boost tests
rcutorture: Make boost test more robust
rcutorture: Add support to detect if boost kthread prio is too low
rcutorture: Fix rcu_barrier successes counter

Mauro Carvalho Chehab (1):
rcu: rcupdate.h: Get rid of Sphinx warnings at rcu_pointer_handoff()

NeilBrown (1):
rculist: Improve documentation for list_for_each_entry_from_rcu()

Paul E. McKenney (98):
rcu: Make expedited grace period use direct call on last leaf
srcu: Fix typos in __call_srcu() header comment
srcu: Document that srcu_funnel_gp_start() implies srcu_funnel_exp_start()
srcu: Add address of first callback to rcutorture output
srcu: Introduce srcu_read_{un,}lock_notrace()
torture: Use a single build directory for torture scenarios
rcutorture: Remove obsolete TREE08-T.boot file
rcutorture: Make kvm-find-errors.sh find close calls
torture: Make online/offline messages appear only for verbose=2
torture: Keep old-school dmesg format
rcu: Add debugging info to assertion
rcu: Exclude near-simultaneous RCU CPU stall warnings
rcu: Diagnostics for grace-period startup hangs
rcu: Make rcu_gp_cleanup() write only once to ->gp_flags
Merge branches 'expedited.2018.07.12a', 'fixes.2018.07.12a', 'srcu.2018.06.25b' and 'torture.2018.06.25b' into HEAD
rcu: Introduce grace-period sequence numbers
rcu: Move rcu_gp_slow() to ->gp_seq
rcu: Make rcutorture's batches-completed API use ->gp_seq
rcu: Convert rcu_check_gp_kthread_starvation() to GP sequence number
rcu: Make quiescent-state reporting use ->gp_seq
rcu: Convert conditional grace-period primitives to ->gp_seq
rcu: Move RCU's grace-period-change code to ->gp_seq
rcu: Convert rcu_gpnum_ovf() to ->gp_seq
rcu: Move rcu_implicit_dynticks_qs() to ->gp_seq
rcu: Move rcu_try_advance_all_cbs() to ->gp_seq
rcu: Move rcu_nocb_gp_get() to ->gp_seq
rcu: Move rcu_gp_in_progress() to ->gp_seq
rcu: Convert ->rcu_iw_gpnum to ->gp_seq
rcu: Convert ->completedqs to ->gp_seq
rcu: Convert grace-period requests to ->gp_seq
rcu: Make RCU CPU stall warnings use ->gp_seq
rcutorture: Convert rcutorture_get_gp_data() to ->gp_seq
rcu: Move from ->need_future_gp[] to ->gp_seq_needed
rcu: Make rcu_nocb_wait_gp() check if GP already requested
rcu: Convert rcu_grace_period tracepoint to gp_seq
rcu: Convert rcu_future_grace_period tracepoint to gp_seq
rcu: Convert rcu_grace_period_init tracepoint to gp_seq
rcu: Convert rcu_preempt_task tracepoint to ->gp_seq
rcu: Convert rcu_unlock_preempted_task tracepoint to ->gp_seq
rcu: Convert rcu_quiescent_state_report tracepoint to ->gp_seq
rcu: Convert rcu_fqs tracepoint to ->gp_seq
rcu: Remove ->gpnum and ->completed
rcu: Make simple callback acceleration refer to rdp->gp_seq_needed
doc: Update data-structure documentation for ->gp_seq
doc: Update memory-ordering documentation for ->gp-seq
doc: Update RCU CPU stall-warning documentation
rcu: Don't funnel-lock above leaf node if GP in progress
rcu: Make rcu_start_this_gp() check for grace period already started
rcutorture: Correctly handle grace-period sequence wrap
rcu: Regularize resetting of rcu_data wrap indicator
rcu: Clean up handling of tasks blocked across full-rcu_node offline
rcu: Fix an obsolete ->qsmaskinit comment
rcu: Make rcu_init_new_rnp() stop upon already-set bit
rcu: Make rcu_report_unblock_qs_rnp() warn on violated preconditions
rcu: Fix typo and add additional debug
rcu: Replace smp_wmb() with smp_store_release() for stall check
rcu: Prevent useless FQS scan after all CPUs have checked in
rcu: Suppress false-positive offline-CPU lockdep-RCU splat
rcu: Suppress false-positive preempted-task splats
rcu: Suppress more involved false-positive preempted-task splats
rcu: Suppress false-positive splats from mid-init task resume
rcu: Fix grace-period hangs from mid-init task resume
rcu: Fix grace-period hangs due to race with CPU offline
rcu: Add RCU-preempt check for waiting on newly onlined CPU
rcu: Move grace-period pre-init delay after pre-init
rcu: Remove failsafe check for lost quiescent state
rcu: Remove CPU-hotplug failsafe from force-quiescent-state code path
rcu: Add up-tree information to dump_blkd_tasks() diagnostics
rcu: Add CPU online/offline state to dump_blkd_tasks()
rcu: Record ->gp_state for both phases of grace-period initialization
rcu: Add diagnostics for offline CPUs failing to report QS
rcu: Make rcu_read_unlock_special() static
rcu: Improve RCU-tasks naming and comments
rcu: Mark task as .need_qs less aggressively
rcu: Inline rcu_dynticks_momentary_idle() into its sole caller
rcu: Clarify and correct the rcu_preempt_qs() header comment
rcu: Remove unused rcu_kick_nohz_cpu() function
rcu: Remove unused local variable "cpu"
rcu: Remove "inline" from panic_on_rcu_stall() and rcu_blocking_is_gp()
rcu: Remove "inline" from rcu_torture_print_module_parms()
rcu: Remove "inline" from rcu_perf_print_module_parms()
rcu: Remove __maybe_unused from rcu_cpu_has_callbacks()
rcu: Use RCU CPU stall timeout for rcu_check_gp_start_stall()
rcu: Add diagnostics for rcutorture writer stall warning
rcu: Make rcu_seq_diff() more exact
MAINTAINERS: Update RCU, SRCU, and TORTURE-TEST entries
rcu: Print stall-warning NMI dyntick state in hexadecimal
srcu: Add grace-period number to rcutorture statistics printout
rcutorture: Change units of onoff_interval to jiffies
rcu: Remove rcutorture test version and sequence number
rcuperf: Remove unused torturing_tasks() function
rcutorture: Extract common code from rcu_torture_reader()
rcutorture: Use atomic increment for n_rcu_torture_timers
rcutorture: Use per-CPU random state for rcu_torture_timer()
rcutorture: Make rcu_torture_timer() use rcu_torture_one_read()
rcutorture: Handle extended read-side critical sections
rcutorture: Emphasize testing of single reader protection type
Merge branches 'fixes1.2018.07.12b' and 'torture1.2018.07.12b' into HEAD

Steven Rostedt (VMware) (2):
rcu: Speed up calling of RCU tasks callbacks
rcu: Add comment to the last sleep in the rcu tasks loop

.../Design/Data-Structures/Data-Structures.html | 118 +--
.../Memory-Ordering/Tree-RCU-Memory-Ordering.html | 22 +-
.../Design/Memory-Ordering/TreeRCU-gp-cleanup.svg | 123 +--
.../Design/Memory-Ordering/TreeRCU-gp-init-1.svg | 16 +-
.../Design/Memory-Ordering/TreeRCU-gp-init-3.svg | 56 +-
.../RCU/Design/Memory-Ordering/TreeRCU-gp.svg | 237 ++---
.../RCU/Design/Memory-Ordering/TreeRCU-qs.svg | 12 +-
Documentation/RCU/stallwarn.txt | 24 +-
Documentation/RCU/whatisRCU.txt | 18 +-
Documentation/admin-guide/kernel-parameters.txt | 4 +-
MAINTAINERS | 9 +-
include/linux/rculist.h | 19 +-
include/linux/rcupdate.h | 20 +-
include/linux/rcutiny.h | 2 +-
include/linux/srcu.h | 17 +
include/linux/torture.h | 4 +-
include/trace/events/rcu.h | 112 ++-
kernel/locking/locktorture.c | 5 +-
kernel/rcu/rcu.h | 104 +-
kernel/rcu/rcuperf.c | 57 +-
kernel/rcu/rcutorture.c | 462 ++++++---
kernel/rcu/srcutree.c | 39 +-
kernel/rcu/tiny.c | 4 +-
kernel/rcu/tree.c | 1019 +++++++++++---------
kernel/rcu/tree.h | 71 +-
kernel/rcu/tree_exp.h | 14 +-
kernel/rcu/tree_plugin.h | 176 ++--
kernel/rcu/update.c | 45 +-
kernel/torture.c | 15 +-
.../testing/selftests/rcutorture/bin/configinit.sh | 26 +-
.../testing/selftests/rcutorture/bin/kvm-build.sh | 11 +-
.../selftests/rcutorture/bin/kvm-recheck-rcu.sh | 1 +
.../selftests/rcutorture/bin/kvm-recheck.sh | 1 +
.../selftests/rcutorture/bin/kvm-test-1-run.sh | 5 +-
tools/testing/selftests/rcutorture/bin/kvm.sh | 2 +-
.../selftests/rcutorture/bin/parse-console.sh | 7 +
.../selftests/rcutorture/configs/rcu/TREE03.boot | 4 +-
.../selftests/rcutorture/configs/rcu/TREE08-T.boot | 1 -
.../rcutorture/configs/rcu/ver_functions.sh | 2 +-
39 files changed, 1675 insertions(+), 1209 deletions(-)
delete mode 100644 tools/testing/selftests/rcutorture/configs/rcu/TREE08-T.boot

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