user/sven/linux.git/kernel/locking, branch v4.2.4

locking/qspinlock/x86: Fix performance regression under unaccelerated VMs

2015-10-22T21:49:15Z

commit 43b3f02899f74ae9914a39547cc5492156f0027a upstream. Dave ran into horrible performance on a VM without PARAVIRT_SPINLOCKS set and Linus noted that the test-and-set implementation was retarded. One should spin on the variable with a load, not a RMW. While there, remove 'queued' from the name, as the lock isn't queued at all, but a simple test-and-set. Suggested-by: Linus Torvalds Reported-by: Dave Chinner Tested-by: Dave Chinner Signed-off-by: Peter Zijlstra (Intel) Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Waiman Long Link: http://lkml.kernel.org/r/20150904152523.GR18673@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

locking/pvqspinlock: Fix kernel panic in locking-selftest

2015-07-21T08:18:07Z

Enabling locking-selftest in a VM guest may cause the following kernel panic: kernel BUG at .../kernel/locking/qspinlock_paravirt.h:137! This is due to the fact that the pvqspinlock unlock function is expecting either a _Q_LOCKED_VAL or _Q_SLOW_VAL in the lock byte. This patch prevents that bug report by ignoring it when debug_locks_silent is set. Otherwise, a warning will be printed if it contains an unexpected value. With this patch applied, the kernel locking-selftest completed without any noise. Tested-by: Masami Hiramatsu Signed-off-by: Waiman Long Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1436663959-53092-1-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar

Merge branch 'sched-hrtimers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2015-06-24T22:09:40Z

Pull scheduler updates from Thomas Gleixner: "This series of scheduler updates depends on sched/core and timers/core branches, which are already in your tree: - Scheduler balancing overhaul to plug a hard to trigger race which causes an oops in the balancer (Peter Zijlstra) - Lockdep updates which are related to the balancing updates (Peter Zijlstra)" * 'sched-hrtimers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched,lockdep: Employ lock pinning lockdep: Implement lock pinning lockdep: Simplify lock_release() sched: Streamline the task migration locking a little sched: Move code around sched,dl: Fix sched class hopping CBS hole sched, dl: Convert switched_{from, to}_dl() / prio_changed_dl() to balance callbacks sched,dl: Remove return value from pull_dl_task() sched, rt: Convert switched_{from, to}_rt() / prio_changed_rt() to balance callbacks sched,rt: Remove return value from pull_rt_task() sched: Allow balance callbacks for check_class_changed() sched: Use replace normalize_task() with __sched_setscheduler() sched: Replace post_schedule with a balance callback list

Merge branch 'sched-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2015-06-24T21:46:01Z

Pull locking updates from Thomas Gleixner: "These locking updates depend on the alreay merged sched/core branch: - Lockless top waiter wakeup for rtmutex (Davidlohr) - Reduce hash bucket lock contention for PI futexes (Sebastian) - Documentation update (Davidlohr)" * 'sched-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking/rtmutex: Update stale plist comments futex: Lower the lock contention on the HB lock during wake up locking/rtmutex: Implement lockless top-waiter wakeup

Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2015-06-23T01:57:44Z

Pull timer updates from Thomas Gleixner: "A rather largish update for everything time and timer related: - Cache footprint optimizations for both hrtimers and timer wheel - Lower the NOHZ impact on systems which have NOHZ or timer migration disabled at runtime. - Optimize run time overhead of hrtimer interrupt by making the clock offset updates smarter - hrtimer cleanups and removal of restrictions to tackle some problems in sched/perf - Some more leap second tweaks - Another round of changes addressing the 2038 problem - First step to change the internals of clock event devices by introducing the necessary infrastructure - Allow constant folding for usecs/msecs_to_jiffies() - The usual pile of clockevent/clocksource driver updates The hrtimer changes contain updates to sched, perf and x86 as they depend on them plus changes all over the tree to cleanup API changes and redundant code, which got copied all over the place. The y2038 changes touch s390 to remove the last non 2038 safe code related to boot/persistant clock" * 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (114 commits) clocksource: Increase dependencies of timer-stm32 to limit build wreckage timer: Minimize nohz off overhead timer: Reduce timer migration overhead if disabled timer: Stats: Simplify the flags handling timer: Replace timer base by a cpu index timer: Use hlist for the timer wheel hash buckets timer: Remove FIFO "guarantee" timers: Sanitize catchup_timer_jiffies() usage hrtimer: Allow hrtimer::function() to free the timer seqcount: Introduce raw_write_seqcount_barrier() seqcount: Rename write_seqcount_barrier() hrtimer: Fix hrtimer_is_queued() hole hrtimer: Remove HRTIMER_STATE_MIGRATE selftest: Timers: Avoid signal deadlock in leap-a-day timekeeping: Copy the shadow-timekeeper over the real timekeeper last clockevents: Check state instead of mode in suspend/resume path selftests: timers: Add leap-second timer edge testing to leap-a-day.c ntp: Do leapsecond adjustment in adjtimex read path time: Prevent early expiry of hrtimers[CLOCK_REALTIME] at the leap second edge ntp: Introduce and use SECS_PER_DAY macro instead of 86400 ...

Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2015-06-22T22:52:04Z

Pull scheduler updates from Ingo Molnar: "The main changes are: - lockless wakeup support for futexes and IPC message queues (Davidlohr Bueso, Peter Zijlstra) - Replace spinlocks with atomics in thread_group_cputimer(), to improve scalability (Jason Low) - NUMA balancing improvements (Rik van Riel) - SCHED_DEADLINE improvements (Wanpeng Li) - clean up and reorganize preemption helpers (Frederic Weisbecker) - decouple page fault disabling machinery from the preemption counter, to improve debuggability and robustness (David Hildenbrand) - SCHED_DEADLINE documentation updates (Luca Abeni) - topology CPU masks cleanups (Bartosz Golaszewski) - /proc/sched_debug improvements (Srikar Dronamraju)" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (79 commits) sched/deadline: Remove needless parameter in dl_runtime_exceeded() sched: Remove superfluous resetting of the p->dl_throttled flag sched/deadline: Drop duplicate init_sched_dl_class() declaration sched/deadline: Reduce rq lock contention by eliminating locking of non-feasible target sched/deadline: Make init_sched_dl_class() __init sched/deadline: Optimize pull_dl_task() sched/preempt: Add static_key() to preempt_notifiers sched/preempt: Fix preempt notifiers documentation about hlist_del() within unsafe iteration sched/stop_machine: Fix deadlock between multiple stop_two_cpus() sched/debug: Add sum_sleep_runtime to /proc//sched sched/debug: Replace vruntime with wait_sum in /proc/sched_debug sched/debug: Properly format runnable tasks in /proc/sched_debug sched/numa: Only consider less busy nodes as numa balancing destinations Revert 095bebf61a46 ("sched/numa: Do not move past the balance point if unbalanced") sched/fair: Prevent throttling in early pick_next_task_fair() preempt: Reorganize the notrace definitions a bit preempt: Use preempt_schedule_context() as the official tracing preemption point sched: Make preempt_schedule_context() function-tracing safe x86: Remove cpu_sibling_mask() and cpu_core_mask() x86: Replace cpu_**_mask() with topology_**_cpumask() ...

Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2015-06-22T21:54:22Z

Pull locking updates from Ingo Molnar: "The main changes are: - 'qspinlock' support, enabled on x86: queued spinlocks - these are now the spinlock variant used by x86 as they outperform ticket spinlocks in every category. (Waiman Long) - 'pvqspinlock' support on x86: paravirtualized variant of queued spinlocks. (Waiman Long, Peter Zijlstra) - 'qrwlock' support, enabled on x86: queued rwlocks. Similar to queued spinlocks, they are now the variant used by x86: CONFIG_ARCH_USE_QUEUED_SPINLOCKS=y CONFIG_QUEUED_SPINLOCKS=y CONFIG_ARCH_USE_QUEUED_RWLOCKS=y CONFIG_QUEUED_RWLOCKS=y - various lockdep fixlets - various locking primitives cleanups, further WRITE_ONCE() propagation" * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits) locking/lockdep: Remove hard coded array size dependency locking/qrwlock: Don't contend with readers when setting _QW_WAITING lockdep: Do not break user-visible string locking/arch: Rename set_mb() to smp_store_mb() locking/arch: Add WRITE_ONCE() to set_mb() rtmutex: Warn if trylock is called from hard/softirq context arch: Remove __ARCH_HAVE_CMPXCHG locking/rtmutex: Drop usage of __HAVE_ARCH_CMPXCHG locking/qrwlock: Rename QUEUE_RWLOCK to QUEUED_RWLOCKS locking/pvqspinlock: Rename QUEUED_SPINLOCK to QUEUED_SPINLOCKS locking/pvqspinlock: Replace xchg() by the more descriptive set_mb() locking/pvqspinlock, x86: Enable PV qspinlock for Xen locking/pvqspinlock, x86: Enable PV qspinlock for KVM locking/pvqspinlock, x86: Implement the paravirt qspinlock call patching locking/pvqspinlock: Implement simple paravirt support for the qspinlock locking/qspinlock: Revert to test-and-set on hypervisors locking/qspinlock: Use a simple write to grab the lock locking/qspinlock: Optimize for smaller NR_CPUS locking/qspinlock: Extract out code snippets for the next patch locking/qspinlock: Add pending bit ...

Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2015-06-22T21:01:01Z

Pull RCU updates from Ingo Molnar: - Continued initialization/Kconfig updates: hide most Kconfig options from unsuspecting users. There's now a single high level configuration option: * * RCU Subsystem * Make expert-level adjustments to RCU configuration (RCU_EXPERT) [N/y/?] (NEW) Which if answered in the negative, leaves us with a single interactive configuration option: Offload RCU callback processing from boot-selected CPUs (RCU_NOCB_CPU) [N/y/?] (NEW) All the rest of the RCU options are configured automatically. Later on we'll remove this single leftover configuration option as well. - Remove all uses of RCU-protected array indexes: replace the rcu_[access|dereference]_index_check() APIs with READ_ONCE() and rcu_lockdep_assert() - RCU CPU-hotplug cleanups - Updates to Tiny RCU: a race fix and further code shrinkage. - RCU torture-testing updates: fixes, speedups, cleanups and documentation updates. - Miscellaneous fixes - Documentation updates * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits) rcutorture: Allow repetition factors in Kconfig-fragment lists rcutorture: Display "make oldconfig" errors rcutorture: Update TREE_RCU-kconfig.txt rcutorture: Make rcutorture scripts force RCU_EXPERT rcutorture: Update configuration fragments for rcutree.rcu_fanout_exact rcutorture: TASKS_RCU set directly, so don't explicitly set it rcutorture: Test SRCU cleanup code path rcutorture: Replace barriers with smp_store_release() and smp_load_acquire() locktorture: Change longdelay_us to longdelay_ms rcutorture: Allow negative values of nreaders to oversubscribe rcutorture: Exchange TREE03 and TREE08 NR_CPUS, speed up CPU hotplug rcutorture: Exchange TREE03 and TREE04 geometries locktorture: fix deadlock in 'rw_lock_irq' type rcu: Correctly handle non-empty Tiny RCU callback list with none ready rcutorture: Test both RCU-sched and RCU-bh for Tiny RCU rcu: Further shrink Tiny RCU by making empty functions static inlines rcu: Conditionally compile RCU's eqs warnings rcu: Remove prompt for RCU implementation rcu: Make RCU able to tolerate undefined CONFIG_RCU_KTHREAD_PRIO rcu: Make RCU able to tolerate undefined CONFIG_RCU_FANOUT_LEAF ...

locking/rtmutex: Update stale plist comments

2015-06-19T19:27:21Z

... as of fb00aca4744 (rtmutex: Turn the plist into an rb-tree) we no longer use plists for queuing any waiters. Update stale comments. Signed-off-by: Davidlohr Bueso Cc: Steven Rostedt Cc: Mike Galbraith Cc: Paul E. McKenney Cc: Sebastian Andrzej Siewior Cc: Davidlohr Bueso Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/1432056298-18738-4-git-send-email-dave@stgolabs.net Signed-off-by: Thomas Gleixner

futex: Lower the lock contention on the HB lock during wake up

2015-06-19T19:26:38Z

wake_futex_pi() wakes the task before releasing the hash bucket lock (HB). The first thing the woken up task usually does is to acquire the lock which requires the HB lock. On SMP Systems this leads to blocking on the HB lock which is released by the owner shortly after. This patch rearranges the unlock path by first releasing the HB lock and then waking up the task. [ tglx: Fixed up the rtmutex unlock path ] Originally-from: Thomas Gleixner Signed-off-by: Sebastian Andrzej Siewior Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Mike Galbraith Cc: Paul E. McKenney Cc: Davidlohr Bueso Link: http://lkml.kernel.org/r/20150617083350.GA2433@linutronix.de Signed-off-by: Thomas Gleixner