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2017-07-06smp/hotplug: Move unparking of percpu threads to the control CPUThomas Gleixner
Vikram reported the following backtrace: BUG: scheduling while atomic: swapper/7/0/0x00000002 CPU: 7 PID: 0 Comm: swapper/7 Not tainted 4.9.32-perf+ #680 schedule schedule_hrtimeout_range_clock schedule_hrtimeout wait_task_inactive __kthread_bind_mask __kthread_bind __kthread_unpark kthread_unpark cpuhp_online_idle cpu_startup_entry secondary_start_kernel He analyzed correctly that a parked cpu hotplug thread of an offlined CPU was still on the runqueue when the CPU came back online and tried to unpark it. This causes the thread which invoked kthread_unpark() to call wait_task_inactive() and subsequently schedule() with preemption disabled. His proposed workaround was to "make sure" that a parked thread has scheduled out when the CPU goes offline, so the situation cannot happen. But that's still wrong because the root cause is not the fact that the percpu thread is still on the runqueue and neither that preemption is disabled, which could be simply solved by enabling preemption before calling kthread_unpark(). The real issue is that the calling thread is the idle task of the upcoming CPU, which is not supposed to call anything which might sleep. The moron, who wrote that code, missed completely that kthread_unpark() might end up in schedule(). The solution is simpler than expected. The thread which controls the hotplug operation is waiting for the CPU to call complete() on the hotplug state completion. So the idle task of the upcoming CPU can set its state to CPUHP_AP_ONLINE_IDLE and invoke complete(). This in turn wakes the control task on a different CPU, which then can safely do the unpark and kick the now unparked hotplug thread of the upcoming CPU to complete the bringup to the final target state. Control CPU AP bringup_cpu(); __cpu_up() ------------> bringup_ap(); bringup_wait_for_ap() wait_for_completion(); cpuhp_online_idle(); <------------ complete(); unpark(AP->stopper); unpark(AP->hotplugthread); while(1) do_idle(); kick(AP->hotplugthread); wait_for_completion(); hotplug_thread() run_online_callbacks(); complete(); Fixes: 8df3e07e7f21 ("cpu/hotplug: Let upcoming cpu bring itself fully up") Reported-by: Vikram Mulukutla <markivx@codeaurora.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Sewior <bigeasy@linutronix.de> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1707042218020.2131@nanos Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-07-03Merge branch 'smp-hotplug-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull SMP hotplug updates from Thomas Gleixner: "This update is primarily a cleanup of the CPU hotplug locking code. The hotplug locking mechanism is an open coded RWSEM, which allows recursive locking. The main problem with that is the recursive nature as it evades the full lockdep coverage and hides potential deadlocks. The rework replaces the open coded RWSEM with a percpu RWSEM and establishes full lockdep coverage that way. The bulk of the changes fix up recursive locking issues and address the now fully reported potential deadlocks all over the place. Some of these deadlocks have been observed in the RT tree, but on mainline the probability was low enough to hide them away." * 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (37 commits) cpu/hotplug: Constify attribute_group structures powerpc: Only obtain cpu_hotplug_lock if called by rtasd ARM/hw_breakpoint: Fix possible recursive locking for arch_hw_breakpoint_init cpu/hotplug: Remove unused check_for_tasks() function perf/core: Don't release cred_guard_mutex if not taken cpuhotplug: Link lock stacks for hotplug callbacks acpi/processor: Prevent cpu hotplug deadlock sched: Provide is_percpu_thread() helper cpu/hotplug: Convert hotplug locking to percpu rwsem s390: Prevent hotplug rwsem recursion arm: Prevent hotplug rwsem recursion arm64: Prevent cpu hotplug rwsem recursion kprobes: Cure hotplug lock ordering issues jump_label: Reorder hotplug lock and jump_label_lock perf/tracing/cpuhotplug: Fix locking order ACPI/processor: Use cpu_hotplug_disable() instead of get_online_cpus() PCI: Replace the racy recursion prevention PCI: Use cpu_hotplug_disable() instead of get_online_cpus() perf/x86/intel: Drop get_online_cpus() in intel_snb_check_microcode() x86/perf: Drop EXPORT of perf_check_microcode ...
2017-06-30cpu/hotplug: Constify attribute_group structuresArvind Yadav
attribute_groups are not supposed to change at runtime. All functions working with attribute_groups provided by <linux/sysfs.h> work with const attribute_group. So mark the non-const structs as const: File size before: text data bss dec hex filename 12582 15361 20 27963 6d3b kernel/cpu.o File size After adding 'const': text data bss dec hex filename 12710 15265 20 27995 6d5b kernel/cpu.o Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: anna-maria@linutronix.de Cc: bigeasy@linutronix.de Cc: boris.ostrovsky@oracle.com Cc: rcochran@linutronix.de Link: http://lkml.kernel.org/r/f9079e94e12b36d245e7adbf67d312bc5d0250c6.1498737970.git.arvind.yadav.cs@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-22genirq/cpuhotplug: Handle managed IRQs on CPU hotplugThomas Gleixner
If a CPU goes offline, interrupts affine to the CPU are moved away. If the outgoing CPU is the last CPU in the affinity mask the migration code breaks the affinity and sets it it all online cpus. This is a problem for affinity managed interrupts as CPU hotplug is often used for power management purposes. If the affinity is broken, the interrupt is not longer affine to the CPUs to which it was allocated. The affinity spreading allows to lay out multi queue devices in a way that they are assigned to a single CPU or a group of CPUs. If the last CPU goes offline, then the queue is not longer used, so the interrupt can be shutdown gracefully and parked until one of the assigned CPUs comes online again. Add a graceful shutdown mechanism into the irq affinity breaking code path, mark the irq as MANAGED_SHUTDOWN and leave the affinity mask unmodified. In the online path, scan the active interrupts for managed interrupts and if the interrupt is functional and the newly online CPU is part of the affinity mask, restart the interrupt if it is marked MANAGED_SHUTDOWN or if the interrupts is started up, try to add the CPU back to the effective affinity mask. Originally-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Jens Axboe <axboe@kernel.dk> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Keith Busch <keith.busch@intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20170619235447.273417334@linutronix.de
2017-06-12cpu/hotplug: Remove unused check_for_tasks() functionArnd Bergmann
clang -Wunused-function found one remaining function that was apparently meant to be removed in a recent code cleanup: kernel/cpu.c:565:20: warning: unused function 'check_for_tasks' [-Wunused-function] Sebastian explained: The function became unused unintentionally, but there is already a failure check, when a task cannot be removed from the outgoing cpu in the scheduler code, so bringing it back is not really giving any extra value. Fixes: 530e9b76ae8f ("cpu/hotplug: Remove obsolete cpu hotplug register/unregister functions") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Anna-Maria Gleixner <anna-maria@linutronix.de> Link: http://lkml.kernel.org/r/20170608085544.2257132-1-arnd@arndb.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-06-03cpu/hotplug: Drop the device lock on errorSebastian Andrzej Siewior
If a custom CPU target is specified and that one is not available _or_ can't be interrupted then the code returns to userland without dropping a lock as notices by lockdep: |echo 133 > /sys/devices/system/cpu/cpu7/hotplug/target | ================================================ | [ BUG: lock held when returning to user space! ] | ------------------------------------------------ | bash/503 is leaving the kernel with locks still held! | 1 lock held by bash/503: | #0: (device_hotplug_lock){+.+...}, at: [<ffffffff815b5650>] lock_device_hotplug_sysfs+0x10/0x40 So release the lock then. Fixes: 757c989b9994 ("cpu/hotplug: Make target state writeable") Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20170602142714.3ogo25f2wbq6fjpj@linutronix.de
2017-05-26cpuhotplug: Link lock stacks for hotplug callbacksThomas Gleixner
The CPU hotplug callbacks are not covered by lockdep versus the cpu hotplug rwsem. CPU0 CPU1 cpuhp_setup_state(STATE, startup, teardown); cpus_read_lock(); invoke_callback_on_ap(); kick_hotplug_thread(ap); wait_for_completion(); hotplug_thread_fn() lock(m); do_stuff(); unlock(m); Lockdep does not know about this dependency and will not trigger on the following code sequence: lock(m); cpus_read_lock(); Add a lockdep map and connect the initiators lock chain with the hotplug thread lock chain, so potential deadlocks can be detected. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20170524081549.709375845@linutronix.de
2017-05-26cpu/hotplug: Convert hotplug locking to percpu rwsemThomas Gleixner
There are no more (known) nested calls to get_online_cpus() and all observed lock ordering problems have been addressed. Replace the magic nested 'rwsem' hackery with a percpu-rwsem. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20170524081549.447014063@linutronix.de
2017-05-26cpu/hotplug: Use stop_machine_cpuslocked() in takedown_cpu()Sebastian Andrzej Siewior
takedown_cpu() is a cpu hotplug function invoking stop_machine(). The cpu hotplug machinery holds the hotplug lock for write. stop_machine() invokes get_online_cpus() as well. This is correct, but prevents the conversion of the hotplug locking to a percpu rwsem. Use stop_machine_cpuslocked() to avoid the nested call. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20170524081548.423292433@linutronix.de
2017-05-26cpu/hotplug: Add __cpuhp_state_add_instance_cpuslocked()Thomas Gleixner
Add cpuslocked() variants for the multi instance registration so this can be called from a cpus_read_lock() protected region. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20170524081547.321782217@linutronix.de
2017-05-26cpu/hotplug: Provide cpuhp_setup/remove_state[_nocalls]_cpuslocked()Sebastian Andrzej Siewior
Some call sites of cpuhp_setup/remove_state[_nocalls]() are within a cpus_read locked region. cpuhp_setup/remove_state[_nocalls]() call cpus_read_lock() as well, which is possible in the current implementation but prevents converting the hotplug locking to a percpu rwsem. Provide locked versions of the interfaces to avoid nested calls to cpus_read_lock(). Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20170524081547.239600868@linutronix.de
2017-05-26cpu/hotplug: Provide cpus_read|write_[un]lock()Thomas Gleixner
The counting 'rwsem' hackery of get|put_online_cpus() is going to be replaced by percpu rwsem. Rename the functions to make it clear that it's locking and not some refcount style interface. These new functions will be used for the preparatory patches which make the code ready for the percpu rwsem conversion. Rename all instances in the cpu hotplug code while at it. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20170524081547.080397752@linutronix.de
2017-04-14Merge branch 'linus' into locking/core, to pick up fixesIngo Molnar
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-26lockdep: Fix per-cpu static objectsPeter Zijlstra
Since commit 383776fa7527 ("locking/lockdep: Handle statically initialized PER_CPU locks properly") we try to collapse per-cpu locks into a single class by giving them all the same key. For this key we choose the canonical address of the per-cpu object, which would be the offset into the per-cpu area. This has two problems: - there is a case where we run !0 lock->key through static_obj() and expect this to pass; it doesn't for canonical pointers. - 0 is a valid canonical address. Cure both issues by redefining the canonical address as the address of the per-cpu variable on the boot CPU. Since I didn't want to rely on CPU0 being the boot-cpu, or even existing at all, track the boot CPU in a variable. Fixes: 383776fa7527 ("locking/lockdep: Handle statically initialized PER_CPU locks properly") Reported-by: kernel test robot <fengguang.wu@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Borislav Petkov <bp@suse.de> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: linux-mm@kvack.org Cc: wfg@linux.intel.com Cc: kernel test robot <fengguang.wu@intel.com> Cc: LKP <lkp@01.org> Link: http://lkml.kernel.org/r/20170320114108.kbvcsuepem45j5cr@hirez.programming.kicks-ass.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-03-14cpu/hotplug: Serialize callback invocations properSebastian Andrzej Siewior
The setup/remove_state/instance() functions in the hotplug core code are serialized against concurrent CPU hotplug, but unfortunately not serialized against themself. As a consequence a concurrent invocation of these function results in corruption of the callback machinery because two instances try to invoke callbacks on remote cpus at the same time. This results in missing callback invocations and initiator threads waiting forever on the completion. The obvious solution to replace get_cpu_online() with cpu_hotplug_begin() is not possible because at least one callsite calls into these functions from a get_online_cpu() locked region. Extend the protection scope of the cpuhp_state_mutex from solely protecting the state arrays to cover the callback invocation machinery as well. Fixes: 5b7aa87e0482 ("cpu/hotplug: Implement setup/removal interface") Reported-and-tested-by: Bart Van Assche <Bart.VanAssche@sandisk.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: hpa@zytor.com Cc: mingo@kernel.org Cc: akpm@linux-foundation.org Cc: torvalds@linux-foundation.org Link: http://lkml.kernel.org/r/20170314150645.g4tdyoszlcbajmna@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-03-02sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar
<linux/sched/task.h> We are going to split <linux/sched/task.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/task.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar
<linux/sched/hotplug.h> We are going to split <linux/sched/hotplug.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/hotplug.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar
<linux/sched/signal.h> We are going to split <linux/sched/signal.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/signal.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-18cpu/hotplug: Remove unused but set variable in _cpu_down()Tobias Klauser
After the recent removal of the hotplug notifiers the variable 'hasdied' in _cpu_down() is set but no longer read, leading to the following GCC warning when building with 'make W=1': kernel/cpu.c:767:7: warning: variable ‘hasdied’ set but not used [-Wunused-but-set-variable] Fix it by removing the variable. Fixes: 530e9b76ae8f ("cpu/hotplug: Remove obsolete cpu hotplug register/unregister functions") Signed-off-by: Tobias Klauser <tklauser@distanz.ch> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20170117143501.20893-1-tklauser@distanz.ch Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-01-16cpu/hotplug: Provide dynamic range for prepare stageThomas Gleixner
Mathieu reported that the LTTNG modules are broken as of 4.10-rc1 due to the removal of the cpu hotplug notifiers. Usually I don't care much about out of tree modules, but LTTNG is widely used in distros. There are two ways to solve that: 1) Reserve a hotplug state for LTTNG 2) Add a dynamic range for the prepare states. While #1 is the simplest solution, #2 is the proper one as we can convert in tree users, which do not care about ordering, to the dynamic range as well. Add a dynamic range which allows LTTNG to request states in the prepare stage. Reported-and-tested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Sewior <bigeasy@linutronix.de> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1701101353010.3401@nanos Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-12-26smp/hotplug: Undo tglxs brainfartThomas Gleixner
The attempt to prevent overwriting an active state resulted in a disaster which effectively disables all dynamically allocated hotplug states. Cleanup the mess. Fixes: dc280d936239 ("cpu/hotplug: Prevent overwriting of callbacks") Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de> Reported-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-25cpu/hotplug: Remove obsolete cpu hotplug register/unregister functionsThomas Gleixner
hotcpu_notifier(), cpu_notifier(), __hotcpu_notifier(), __cpu_notifier(), register_hotcpu_notifier(), register_cpu_notifier(), __register_hotcpu_notifier(), __register_cpu_notifier(), unregister_hotcpu_notifier(), unregister_cpu_notifier(), __unregister_hotcpu_notifier(), __unregister_cpu_notifier() are unused now. Remove them and all related code. Remove also the now pointless cpu notifier error injection mechanism. The states can be executed step by step and error rollback is the same as cpu down, so any state transition can be tested w/o requiring the notifier error injection. Some CPU hotplug states are kept as they are (ab)used for hotplug state tracking. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20161221192112.005642358@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-12-25cpu/hotplug: Prevent overwriting of callbacksThomas Gleixner
Developers manage to overwrite states blindly without thought. That's fatal and hard to debug. Add sanity checks to make it fail. This requries to restructure the code so that the dynamic state allocation happens in the same lock protected section as the actual store. Otherwise the previous assignment of 'Reserved' to the name field would trigger the overwrite check. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Link: http://lkml.kernel.org/r/20161221192111.675234535@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-12-15cpu/hotplug: Clarify description of __cpuhp_setup_state() return valueBoris Ostrovsky
When invoked with CPUHP_AP_ONLINE_DYN state __cpuhp_setup_state() is expected to return positive value which is the hotplug state that the routine assigns. Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: linux-pm@vger.kernel.org Cc: viresh.kumar@linaro.org Cc: bigeasy@linutronix.de Cc: rjw@rjwysocki.net Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/1481814058-4799-2-git-send-email-boris.ostrovsky@oracle.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-12-08hotplug: Make register and unregister notifier API symmetricMichal Hocko
Yu Zhao has noticed that __unregister_cpu_notifier only unregisters its notifiers when HOTPLUG_CPU=y while the registration might succeed even when HOTPLUG_CPU=n if MODULE is enabled. This means that e.g. zswap might keep a stale notifier on the list on the manual clean up during the pool tear down and thus corrupt the list. Resulting in the following [ 144.964346] BUG: unable to handle kernel paging request at ffff880658a2be78 [ 144.971337] IP: [<ffffffffa290b00b>] raw_notifier_chain_register+0x1b/0x40 <snipped> [ 145.122628] Call Trace: [ 145.125086] [<ffffffffa28e5cf8>] __register_cpu_notifier+0x18/0x20 [ 145.131350] [<ffffffffa2a5dd73>] zswap_pool_create+0x273/0x400 [ 145.137268] [<ffffffffa2a5e0fc>] __zswap_param_set+0x1fc/0x300 [ 145.143188] [<ffffffffa2944c1d>] ? trace_hardirqs_on+0xd/0x10 [ 145.149018] [<ffffffffa2908798>] ? kernel_param_lock+0x28/0x30 [ 145.154940] [<ffffffffa2a3e8cf>] ? __might_fault+0x4f/0xa0 [ 145.160511] [<ffffffffa2a5e237>] zswap_compressor_param_set+0x17/0x20 [ 145.167035] [<ffffffffa2908d3c>] param_attr_store+0x5c/0xb0 [ 145.172694] [<ffffffffa290848d>] module_attr_store+0x1d/0x30 [ 145.178443] [<ffffffffa2b2b41f>] sysfs_kf_write+0x4f/0x70 [ 145.183925] [<ffffffffa2b2a5b9>] kernfs_fop_write+0x149/0x180 [ 145.189761] [<ffffffffa2a99248>] __vfs_write+0x18/0x40 [ 145.194982] [<ffffffffa2a9a412>] vfs_write+0xb2/0x1a0 [ 145.200122] [<ffffffffa2a9a732>] SyS_write+0x52/0xa0 [ 145.205177] [<ffffffffa2ff4d97>] entry_SYSCALL_64_fastpath+0x12/0x17 This can be even triggered manually by changing /sys/module/zswap/parameters/compressor multiple times. Fix this issue by making unregister APIs symmetric to the register so there are no surprises. Fixes: 47e627bc8c9a ("[PATCH] hotplug: Allow modules to use the cpu hotplug notifiers even if !CONFIG_HOTPLUG_CPU") Reported-and-tested-by: Yu Zhao <yuzhao@google.com> Signed-off-by: Michal Hocko <mhocko@suse.com> Cc: linux-mm@kvack.org Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dan Streetman <ddstreet@ieee.org> Link: http://lkml.kernel.org/r/20161207135438.4310-1-mhocko@kernel.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-10-16cpu/hotplug: Use distinct name for cpu_hotplug.dep_mapJoonas Lahtinen
Use distinctive name for cpu_hotplug.dep_map to avoid the actual cpu_hotplug.lock appearing as cpu_hotplug.lock#2 in lockdep splats. Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Acked-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Gautham R . Shenoy <ego@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: intel-gfx@lists.freedesktop.org Cc: trivial@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-10-03Merge branch 'smp-hotplug-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull CPU hotplug updates from Thomas Gleixner: "Yet another batch of cpu hotplug core updates and conversions: - Provide core infrastructure for multi instance drivers so the drivers do not have to keep custom lists. - Convert custom lists to the new infrastructure. The block-mq custom list conversion comes through the block tree and makes the diffstat tip over to more lines removed than added. - Handle unbalanced hotplug enable/disable calls more gracefully. - Remove the obsolete CPU_STARTING/DYING notifier support. - Convert another batch of notifier users. The relayfs changes which conflicted with the conversion have been shipped to me by Andrew. The remaining lot is targeted for 4.10 so that we finally can remove the rest of the notifiers" * 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (46 commits) cpufreq: Fix up conversion to hotplug state machine blk/mq: Reserve hotplug states for block multiqueue x86/apic/uv: Convert to hotplug state machine s390/mm/pfault: Convert to hotplug state machine mips/loongson/smp: Convert to hotplug state machine mips/octeon/smp: Convert to hotplug state machine fault-injection/cpu: Convert to hotplug state machine padata: Convert to hotplug state machine cpufreq: Convert to hotplug state machine ACPI/processor: Convert to hotplug state machine virtio scsi: Convert to hotplug state machine oprofile/timer: Convert to hotplug state machine block/softirq: Convert to hotplug state machine lib/irq_poll: Convert to hotplug state machine x86/microcode: Convert to hotplug state machine sh/SH-X3 SMP: Convert to hotplug state machine ia64/mca: Convert to hotplug state machine ARM/OMAP/wakeupgen: Convert to hotplug state machine ARM/shmobile: Convert to hotplug state machine arm64/FP/SIMD: Convert to hotplug state machine ...
2016-10-03Merge branch 'core-rcu-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull RCU updates from Ingo Molnar: "The main changes in this cycle were: - Expedited grace-period changes, most notably avoiding having user threads drive expedited grace periods, using a workqueue instead. - Miscellaneous fixes, including a performance fix for lists that was sent with the lists modifications. - CPU hotplug updates, most notably providing exact CPU-online tracking for RCU. This will in turn allow removal of the checks supporting RCU's prior heuristic that was based on the assumption that CPUs would take no longer than one jiffy to come online. - Torture-test updates. - Documentation updates" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (22 commits) list: Expand list_first_entry_or_null() torture: TOROUT_STRING(): Insert a space between flag and message rcuperf: Consistently insert space between flag and message rcutorture: Print out barrier error as document says torture: Add task state to writer-task stall printk()s torture: Convert torture_shutdown() to hrtimer rcutorture: Convert to hotplug state machine cpu/hotplug: Get rid of CPU_STARTING reference rcu: Provide exact CPU-online tracking for RCU rcu: Avoid redundant quiescent-state chasing rcu: Don't use modular infrastructure in non-modular code sched: Make wake_up_nohz_cpu() handle CPUs going offline rcu: Use rcu_gp_kthread_wake() to wake up grace period kthreads rcu: Use RCU's online-CPU state for expedited IPI retry rcu: Exclude RCU-offline CPUs from expedited grace periods rcu: Make expedited RCU CPU stall warnings respond to controls rcu: Stop disabling expedited RCU CPU stall warnings rcu: Drive expedited grace periods from workqueue rcu: Consolidate expedited grace period machinery documentation: Record reason for rcu_head two-byte alignment ...
2016-09-06slab: Convert to hotplug state machineSebastian Andrzej Siewior
Install the callbacks via the state machine. Signed-off-by: Richard Weinberger <richard@nod.at> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: linux-mm@kvack.org Cc: rt@linutronix.de Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Christoph Lameter <cl@linux.com> Link: http://lkml.kernel.org/r/20160823125319.abeapfjapf2kfezp@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-09-06relayfs: Convert to hotplug state machineRichard Weinberger
Install the callbacks via the state machine. They are installed at run time but relay_prepare_cpu() does not need to be invoked by the boot CPU because relay_open() was not yet invoked and there are no pools that need to be created. Signed-off-by: Richard Weinberger <richard@nod.at> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20160818125731.27256-3-bigeasy@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-09-06cpu/hotplug: Remove CPU_STARTING and CPU_DYING notifierThomas Gleixner
All users are converted to state machine, remove CPU_STARTING and the corresponding CPU_DYING. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160818125731.27256-2-bigeasy@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-09-06cpu/hotplug: Make state names consistentThomas Gleixner
We should have all names in the scheme "[subsys/]facility:state]". Fix the core to comply. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-09-05cpu/hotplug: Replace anon unionThomas Gleixner
Some compilers are unhappy with the anon union in the state array. Replace it with a named union. While at it align the state array initializers proper and add the missing name tags. Fixes: cf392d10b69e "cpu/hotplug: Add multi instance support" Reported-by: Ingo Molnar <mingo@kernel.org> Reported-by: Fenguang Wu <fengguang.wu@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: rt@linutronix.de
2016-09-02cpu/hotplug: Handle unbalanced hotplug enable/disableLianwei Wang
When cpu_hotplug_enable() is called unbalanced w/o a preceeding cpu_hotplug_disable() the code emits a warning, but happily decrements the disabled counter. This causes the next operations to malfunction. Prevent the decrement and just emit a warning. Signed-off-by: Lianwei Wang <lianwei.wang@gmail.com> Cc: peterz@infradead.org Cc: linux-pm@vger.kernel.org Cc: oleg@redhat.com Link: http://lkml.kernel.org/r/1465541008-12476-1-git-send-email-lianwei.wang@gmail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-09-02cpu/hotplug: Add multi instance supportThomas Gleixner
This patch adds the ability for a given state to have multiple instances. Until now all states have a single instance and the startup / teardown callback use global variables. A few drivers need to perform a the same callbacks on multiple "instances". Currently we have three drivers in tree which all have a global list which they iterate over. With multi instance they support don't need their private list and the functionality has been moved into core code. Plus we hold the hotplug lock in core so no cpus comes/goes while instances are registered and we do rollback in error case :) Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/1471024183-12666-3-git-send-email-bigeasy@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-09-02cpu/hotplug: Rework callback invocation logicThomas Gleixner
This is preparation for the following patch. This rework here changes the arguments of cpuhp_invoke_callback(). It passes now `state' and whether `startup' or `teardown' callback should be invoked. The callback then is looked up by the function. The following is a clanup of callers: - cpuhp_issue_call() has one argument less - struct cpuhp_cpu_state (which is used by the hotplug thread) gets also its callback removed. The decision if it is a single callback invocation moved to the `single' variable. Also a `bringup' variable has been added to distinguish between startup and teardown callback. - take_cpu_down() needs to start one step earlier. We always get here via CPUHP_TEARDOWN_CPU callback. Before that change cpuhp_ap_states + CPUHP_TEARDOWN_CPU pointed to an empty entry because TEARDOWN is saved in bp_states for this reason. Now that we use cpuhp_get_step() to lookup the state we must explicitly skip it in order not to invoke it twice. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/1471024183-12666-2-git-send-email-bigeasy@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-08-26cpu/hotplug: Allow suspend/resume CPU to be specifiedJames Morse
disable_nonboot_cpus() assumes that the lowest numbered online CPU is the boot CPU, and that this is the correct CPU to run any power management code on. On x86 this is always correct, as CPU0 cannot (easily) by taken offline. On arm64 CPU0 can be taken offline. For hibernate/resume this means we may hibernate on a CPU other than CPU0. If the system is rebooted with kexec 'CPU0' will be assigned to a different physical CPU. This complicates hibernate/resume as now we can't trust the CPU numbers. Arch code can find the correct physical CPU, and ensure it is online before resume from hibernate begins, but also needs to influence disable_nonboot_cpus()s choice of CPU. Rename disable_nonboot_cpus() as freeze_secondary_cpus() and add an argument indicating which CPU should be left standing. Follow the logic in migrate_to_reboot_cpu() to use the lowest numbered online CPU if the requested CPU is not online. Add disable_nonboot_cpus() as an inline function that has the existing behaviour. Cc: Rafael J. Wysocki <rjw@rjwysocki.net> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2016-08-22cpu/hotplug: Get rid of CPU_STARTING referenceSebastian Andrzej Siewior
CPU_STARTING is scheduled for removal. There is no use of it in drivers and core code uses it only for compatibility with old-style CPU-hotplug notifiers. This patch removes therefore removes CPU_STARTING from an RCU-related comment. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-08-22rcu: Provide exact CPU-online tracking for RCUPaul E. McKenney
Up to now, RCU has assumed that the CPU-online process makes it from CPU_UP_PREPARE to set_cpu_online() within one jiffy. Given the recent rise of virtualized environments, this assumption is very clearly obsolete. Failing to meet this deadline can result in RCU paying attention to an incoming CPU for one jiffy, then ignoring it until the grace period following the one in which that CPU sets itself online. This situation might prove to be fatally disappointing to any RCU read-side critical sections that had the misfortune to execute during the time in which RCU was ignoring the slow-to-come-online CPU. This commit therefore updates RCU's internal CPU state-tracking information at notify_cpu_starting() time, thus providing RCU with an exact transition of the CPU's state from offline to online. Note that this means that incoming CPUs must not use RCU read-side critical section (other than those of SRCU) until notify_cpu_starting() time. Note also that the CPU_STARTING notifiers -are- allowed to use RCU read-side critical sections. (Of course, CPU-hotplug notifiers are rapidly becoming obsolete, so you need to act fast!) If a given architecture or CPU family needs to use RCU read-side critical sections earlier, the call to rcu_cpu_starting() from notify_cpu_starting() will need to be architecture-specific, with architectures that need early use being required to hand-place the call to rcu_cpu_starting() at some point preceding the call to notify_cpu_starting(). Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-08-10cpu/hotplug: Prevent alloc/free of irq descriptors during CPU up/down (again)Boris Ostrovsky
Now that Xen no longer allocates irqs in _cpu_up() we can restore commit: a89941816726 ("hotplug: Prevent alloc/free of irq descriptors during cpu up/down") Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Reviewed-by: Juergen Gross <jgross@suse.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: Anna-Maria Gleixner <anna-maria@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: david.vrabel@citrix.com Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/1470244948-17674-3-git-send-email-boris.ostrovsky@oracle.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-28timers/core: Correct callback order during CPU hot plugRichard Cochran
On the tear-down path, the dead CPU callback for the timers was misplaced within the 'cpuhp_state' enumeration. There is a hidden dependency between the timers and block multiqueue. The timers callback must happen before the block multiqueue callback otherwise a RCU stall occurs. Move the timers callback to the proper place in the state machine. Reported-and-tested-by: Jon Hunter <jonathanh@nvidia.com> Reported-by: kbuild test robot <lkp@intel.com> Fixes: 24f73b99716a ("timers/core: Convert to hotplug state machine") Signed-off-by: Richard Cochran <rcochran@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: John Stultz <john.stultz@linaro.org> Cc: rt@linutronix.de Cc: Oleg Nesterov <oleg@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1469610498-25914-1-git-send-email-rcochran@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-15rcu: Convert rcutree to hotplug state machineThomas Gleixner
Straight forward conversion to the state machine. Though the question arises whether this needs really all these state transitions to work. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160713153337.982013161@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-15smp/cfd: Convert core to hotplug state machineRichard Weinberger
Install the callbacks via the state machine. They are installed at runtime so smpcfd_prepare_cpu() needs to be invoked by the boot-CPU. Signed-off-by: Richard Weinberger <richard@nod.at> [ Added the dropped CPU dying case back in. ] Signed-off-by: Richard Cochran <rcochran@linutronix.de> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Davidlohr Bueso <dave@stgolabs> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160713153337.818376366@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-15timers/core: Convert to hotplug state machineRichard Cochran
When tearing down, call timers_dead_cpu() before notify_dead(). There is a hidden dependency between: - timers - block multiqueue - rcutree If timers_dead_cpu() comes later than blk_mq_queue_reinit_notify() that latter function causes a RCU stall. Signed-off-by: Richard Cochran <rcochran@linutronix.de> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: John Stultz <john.stultz@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160713153337.566790058@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-15hrtimer: Convert to hotplug state machineThomas Gleixner
Split out the clockevents callbacks instead of piggybacking them on hrtimers. This gets rid of a POST_DEAD user. See commit: 54e88fad223c ("sched: Make sure timers have migrated before killing the migration_thread") We just move the callback state to the proper place in the state machine. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160713153337.485419196@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-14workqueue: Convert to state machine callbacksThomas Gleixner
Get rid of the prio ordering of the separate notifiers and use a proper state callback pair. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Acked-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nicolas Iooss <nicolas.iooss_linux@m4x.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160713153335.197083890@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-14perf/core: Convert to hotplug state machineThomas Gleixner
Actually a nice symmetric startup/teardown pair which fits properly into the state machine concept. In the long run we should be able to invoke the startup callback for the boot CPU via the state machine and get rid of the init function which invokes it on the boot CPU. Note: This comes actually before the perf hardware callbacks. In the notifier model the hardware callbacks have a higher priority than the core callback. But that's solely for CPU offline so that hardware migration of events happens before the core is notified about the outgoing CPU. With the symetric state array model we have the following ordering: UP: core -> hardware DOWN: hardware -> core Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> Reviewed-by: Sebastian Siewior <bigeasy@linutronix.de> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160713153333.587514098@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-14cpu/hotplug: Handle early registration gracefullyThomas Gleixner
We switched the hotplug machinery to smpboot threads. Early registration of hotplug callbacks, i.e. from do_pre_smp_initcalls(), happens before the threads are initialized. Instead of moving the thread init, we simply handle it in the hotplug code itself and invoke the function directly. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160713153332.896450738@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-13cpu/hotplug: Keep enough storage space if SMP=n to avoid array out of bounds ↵Thomas Gleixner
scribble Xiaolong Ye reported lock debug warnings triggered by the following commit: 8de4a0066106 ("perf/x86: Convert the core to the hotplug state machine") The bug is the following: the cpuhp_bp_states[] array is cut short when CONFIG_SMP=n, but the dynamically registered callbacks are stored nevertheless and happily scribble outside of the array bounds... We need to store them in case that the state is unregistered so we can invoke the teardown function. That's independent of CONFIG_SMP. Make sure the array is large enough. Reported-by: kernel test robot <xiaolong.ye@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Adam Borowski <kilobyte@angband.pl> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Anna-Maria Gleixner <anna-maria@linutronix.de> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Borislav Petkov <bp@suse.de> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Kan Liang <kan.liang@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Stephane Eranian <eranian@google.com> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: lkp@01.org Cc: stable@vger.kernel.org Cc: tipbuild@zytor.com Fixes: cff7d378d3fd "cpu/hotplug: Convert to a state machine for the control processor" Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1607122144560.4083@nanos Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-06sched/hotplug: Make activate() the last hotplug stepThomas Gleixner
The scheduler can handle per cpu threads before the cpu is set to active and it does not allow user space threads on the cpu before active is set. Attaching to the scheduling domains is also not required before user space threads can be handled. Move the activation to the end of the hotplug state space. That also means that deactivation is the first action when a cpu is shut down. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160310120025.597477199@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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