Re: [RFC GIT PULL rcu/next] v2 RCU commits for 3.7

[Ingo Molnar <mingo@kernel.org>]

* Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote:

> Hello, Ingo,
> 
> This is now an RFC pull for only one of the previous two reasons.
> The commits have how been through -next without the adaptive-idle patches,
> but although good progress has been made on the adaptive-idle patches,
> they are still not quite there yet.  Again, the current adaptive-idle
> series has been rebased as rcu/idle on top of rcu/next, the latter branch
> being the subject of this pull request.  Also, I have merged the
> conflicting -tip branches into rcu/next, resolving the conflicts.
> (One set was adjacent insertions/deletions, the other was resolved
> as Peter Zijlstra described at https://lkml.org/lkml/2012/9/5/585.
> 
> Again, the major features of this series are:
> 
> 0.	A fix for a latent bug that has been in RCU ever since the
> 	addition of CPU stall warnings.  This bug results in
> 	false-positive stall warnings, but thus far only on embedded
> 	systems with severely cut-down userspace configurations.
> 	This fix is located on an rcu/urgent branch, with the rest
> 	of the commits based on top of it.  This commit CCs stable.
> 	Given that the merge window is coming quite soon and given
> 	the small number of affected users, I do -not- recommend
> 	pushing it to 3.6, but the separate branch makes it easy to
> 	find if someone needs it.
> 
> 1.	Further reductions in latency spikes for huge systems, along
> 	with additional boot-time adaptation to the actual hardware.
> 	This is a large change, as it moves RCU grace-period
> 	initialization and cleanup, along with quiescent-state forcing,
> 	from softirq to a kthread.  However, it appears to be in
> 	quite good shape (famous last words).  Posted to LKML at
> 	https://lkml.org/lkml/2012/9/20/427.
> 
> 2.	Updates to documentation and rcutorture, the latter category
> 	including keeping statistics on CPU-hotplug latencies and
> 	fixing some initialization-time races.  Posted to LKML at
> 	https://lkml.org/lkml/2012/8/30/193.
> 
> 3.	Miscellaneous fixes and improvements, posted to LKML at
> 	https://lkml.org/lkml/2012/8/30/199.
> 
> 4.	CPU-hotplug fixes and improvements, posted to LKML at
> 	https://lkml.org/lkml/2012/8/30/292 for first three and at
> 	https://lkml.org/lkml/2012/8/3/416.
> 
> 5.	Idle-loop fixes that were omitted on an earlier submission,
> 	posted to LKML at https://lkml.org/lkml/2012/8/30/251.
> 
> As noted earlier, all of these commits have been exposed to -next testing,
> albeit in combination with adaptive-idle commits that will hopefully be
> following soon.
> 
> These changes are available in the git repository at:
> 
> git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git rcu/next
> 
> 							Thanx, Paul
> 
> -------------------->
> Dimitri Sivanich (1):
>       rcu: Segregate rcu_state fields to improve cache locality
> 
> Frederic Weisbecker (11):
>       alpha: Fix preemption handling in idle loop
>       alpha: Add missing RCU idle APIs on idle loop
>       cris: Add missing RCU idle APIs on idle loop
>       frv: Add missing RCU idle APIs on idle loop
>       h8300: Add missing RCU idle APIs on idle loop
>       m32r: Add missing RCU idle APIs on idle loop
>       m68k: Add missing RCU idle APIs on idle loop
>       mn10300: Add missing RCU idle APIs on idle loop
>       parisc: Add missing RCU idle APIs on idle loop
>       score: Add missing RCU idle APIs on idle loop
>       xtensa: Add missing RCU idle APIs on idle loop
> 
> Li Zhong (1):
>       rcu: Move TINY_RCU quiescent state out of extended quiescent state
> 
> Michael Wang (1):
>       kmemleak: Replace list_for_each_continue_rcu with new interface
> 
> Paul E. McKenney (46):
>       rcu: Move RCU grace-period initialization into a kthread
>       rcu: Prevent initialization-time quiescent-state race
>       rcu: Allow RCU grace-period initialization to be preempted
>       rcu: Move RCU grace-period cleanup into kthread
>       rcu: Allow RCU grace-period cleanup to be preempted
>       rcu: Break up rcu_gp_kthread() into subfunctions
>       rcu: Prevent offline CPUs from executing RCU core code
>       rcu: Provide OOM handler to motivate lazy RCU callbacks
>       rcu: Move quiescent-state forcing into kthread
>       rcu: Allow RCU quiescent-state forcing to be preempted
>       rcu: Adjust debugfs tracing for kthread-based quiescent-state forcing
>       rcu: Prevent force_quiescent_state() memory contention
>       rcu: Control grace-period duration from sysfs
>       rcu: Make rcutree module parameters visible in sysfs
>       rcu: Fix day-zero grace-period initialization/cleanup race
>       rcu: Add random PROVE_RCU_DELAY to grace-period initialization
>       rcu: Adjust for unconditional ->completed assignment
>       rcu: Eliminate signed overflow in synchronize_rcu_expedited()
>       rcu: Reduce synchronize_rcu_expedited() latency
>       rcu: Simplify quiescent-state detection
>       rcu: Handle unbalanced rcu_node configurations with few CPUs
>       rcu: Shrink RCU based on number of CPUs
>       rcu: Update rcutorture defaults
>       rcu: Track CPU-hotplug duration statistics
>       rcu: Document SRCU dead-CPU capabilities, emphasize read-side limits
>       rcu: Switch rcutorture to pr_alert() and friends
>       rcu: Prevent initialization race in rcutorture kthreads
>       rcu: Add PROVE_RCU_DELAY to provoke difficult races
>       rcu: Pull TINY_RCU dyntick-idle tracing into non-idle region
>       rcu: Properly initialize ->boost_tasks on CPU offline
>       rcu: Permit RCU_NONIDLE() to be used from interrupt context
>       rcu: Improve boost selection when moving tasks to root rcu_node
>       rcu: Make offline-CPU checking allow for indefinite delays
>       rcu: Fix obsolete rcu_initiate_boost() header comment
>       rcu: Apply for_each_rcu_flavor() to increment_cpu_stall_ticks()
>       rcu: Avoid rcu_print_detail_task_stall_rnp() segfault
>       rcu: Protect rcu_node accesses during CPU stall warnings
>       rcu: Avoid spurious RCU CPU stall warnings
>       rcu: Remove redundant memory barrier from __call_rcu()
>       rcu: Move TINY_PREEMPT_RCU away from raw_local_irq_save()
>       time: RCU permitted to stop idle entry via softirq
>       rcu: Fix CONFIG_RCU_FAST_NO_HZ stall warning message
>       rcu: Remove _rcu_barrier() dependency on __stop_machine()
>       rcu: Disallow callback registry on offline CPUs
>       ia64: Add missing RCU idle APIs on idle loop
>       Merge branches 'bigrt.2012.09.23a', 'doctorture.2012.09.23a', 'fixes.2012.09.23a', 'hotplug.2012.09.23a' and 'idlechop.2012.09.23a' into HEAD
> 
> Peter Zijlstra (1):
>       sched: Fix load avg vs cpu-hotplug
> 
> Silas Boyd-Wickizer (2):
>       Use get_online_cpus to avoid races involving CPU hotplug
>       Use get_online_cpus to avoid races involving CPU hotplug
> 
>  Documentation/RCU/checklist.txt     |    6 +
>  Documentation/RCU/stallwarn.txt     |   16 +-
>  Documentation/RCU/trace.txt         |   43 +--
>  Documentation/RCU/whatisRCU.txt     |    9 +-
>  Documentation/kernel-parameters.txt |   11 +
>  arch/alpha/kernel/process.c         |    6 +-
>  arch/alpha/kernel/smp.c             |    1 +
>  arch/cris/kernel/process.c          |    3 +
>  arch/frv/kernel/process.c           |    3 +
>  arch/h8300/kernel/process.c         |    3 +
>  arch/ia64/kernel/process.c          |    3 +
>  arch/m32r/kernel/process.c          |    3 +
>  arch/m68k/kernel/process.c          |    3 +
>  arch/mn10300/kernel/process.c       |    3 +
>  arch/parisc/kernel/process.c        |    3 +
>  arch/score/kernel/process.c         |    4 +-
>  arch/x86/kernel/cpuid.c             |    5 +
>  arch/x86/kernel/msr.c               |    5 +
>  arch/xtensa/kernel/process.c        |    3 +
>  include/linux/interrupt.h           |    2 +
>  include/linux/rcupdate.h            |    6 +-
>  kernel/rcupdate.c                   |    4 +
>  kernel/rcutiny.c                    |   33 +-
>  kernel/rcutiny_plugin.h             |   10 +-
>  kernel/rcutorture.c                 |  159 +++++----
>  kernel/rcutree.c                    |  690 ++++++++++++++++++-----------------
>  kernel/rcutree.h                    |   31 +-
>  kernel/rcutree_plugin.h             |  174 +++++++--
>  kernel/rcutree_trace.c              |   19 +-
>  kernel/sched/core.c                 |   41 +-
>  kernel/time/tick-sched.c            |    3 +-
>  lib/Kconfig.debug                   |   14 +
>  mm/kmemleak.c                       |    6 +-
>  33 files changed, 771 insertions(+), 554 deletions(-)

Pulled, thanks a lot Paul!

	Ingo