linux/kernel/sched, branch v5.11

sched: Relax the set_cpus_allowed_ptr() semantics

2021-01-22T14:09:44Z

Now that we have KTHREAD_IS_PER_CPU to denote the critical per-cpu tasks to retain during CPU offline, we can relax the warning in set_cpus_allowed_ptr(). Any spurious kthread that wants to get on at the last minute will get pushed off before it can run. While during CPU online there is no harm, and actual benefit, to allowing kthreads back on early, it simplifies hotplug code and fixes a number of outstanding races. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Lai jiangshan Reviewed-by: Valentin Schneider Tested-by: Valentin Schneider Link: https://lkml.kernel.org/r/20210121103507.240724591@infradead.org

sched: Fix CPU hotplug / tighten is_per_cpu_kthread()

2021-01-22T14:09:44Z

Prior to commit 1cf12e08bc4d ("sched/hotplug: Consolidate task migration on CPU unplug") we'd leave any task on the dying CPU and break affinity and force them off at the very end. This scheme had to change in order to enable migrate_disable(). One cannot wait for migrate_disable() to complete while stuck in stop_machine(). Furthermore, since we need at the very least: idle, hotplug and stop threads at any point before stop_machine, we can't break affinity and/or push those away. Under the assumption that all per-cpu kthreads are sanely handled by CPU hotplug, the new code no long breaks affinity or migrates any of them (which then includes the critical ones above). However, there's an important difference between per-cpu kthreads and kthreads that happen to have a single CPU affinity which is lost. The latter class very much relies on the forced affinity breaking and migration semantics previously provided. Use the new kthread_is_per_cpu() infrastructure to tighten is_per_cpu_kthread() and fix the hot-unplug problems stemming from the change. Fixes: 1cf12e08bc4d ("sched/hotplug: Consolidate task migration on CPU unplug") Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Valentin Schneider Tested-by: Valentin Schneider Link: https://lkml.kernel.org/r/20210121103507.102416009@infradead.org

sched: Prepare to use balance_push in ttwu()

2021-01-22T14:09:43Z

In preparation of using the balance_push state in ttwu() we need it to provide a reliable and consistent state. The immediate problem is that rq->balance_callback gets cleared every schedule() and then re-set in the balance_push_callback() itself. This is not a reliable signal, so add a variable that stays set during the entire time. Also move setting it before the synchronize_rcu() in sched_cpu_deactivate(), such that we get guaranteed visibility to ttwu(), which is a preempt-disable region. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Valentin Schneider Tested-by: Valentin Schneider Link: https://lkml.kernel.org/r/20210121103506.966069627@infradead.org

sched: Don't run cpu-online with balance_push() enabled

2021-01-22T14:09:42Z

We don't need to push away tasks when we come online, mark the push complete right before the CPU dies. XXX hotplug state machine has trouble with rollback here. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Valentin Schneider Tested-by: Valentin Schneider Link: https://lkml.kernel.org/r/20210121103506.415606087@infradead.org

sched/core: Print out straggler tasks in sched_cpu_dying()

2021-01-22T14:09:41Z

Since commit 1cf12e08bc4d ("sched/hotplug: Consolidate task migration on CPU unplug") tasks are expected to move themselves out of a out-going CPU. For most tasks this will be done automagically via BALANCE_PUSH, but percpu kthreads will have to cooperate and move themselves away one way or another. Currently, some percpu kthreads (workqueues being a notable exemple) do not cooperate nicely and can end up on an out-going CPU at the time sched_cpu_dying() is invoked. Print the dying rq's tasks to shed some light on the stragglers. Signed-off-by: Valentin Schneider Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Valentin Schneider Tested-by: Valentin Schneider Link: https://lkml.kernel.org/r/20210113183141.11974-1-valentin.schneider@arm.com

Merge tag 'sched-urgent-2020-12-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-12-27T17:00:47Z

Pull scheduler fix from Ingo Molnar: "Fix a context switch performance regression" * tag 'sched-urgent-2020-12-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched: Optimize finish_lock_switch()

Merge tag 'pm-5.11-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

2020-12-22T22:12:10Z

Pull more power management updates from Rafael Wysocki: "These update the CPPC cpufreq driver and intel_pstate (which involves updating the cpufreq core and the schedutil governor) and make janitorial changes in the ACPI code handling processor objects. Specifics: - Rework the passive-mode "fast switch" path in the intel_pstate driver to allow it receive the minimum (required) and target (desired) performance information from the schedutil governor so as to avoid running some workloads too fast (Rafael Wysocki). - Make the intel_pstate driver allow the policy max limit to be increased after the guaranteed performance value for the given CPU has increased (Rafael Wysocki). - Clean up the handling of CPU coordination types in the CPPC cpufreq driver and make it export frequency domains information to user space via sysfs (Ionela Voinescu). - Fix the ACPI code handling processor objects to use a correct coordination type when it fails to map frequency domains and drop a redundant CPU map initialization from it (Ionela Voinescu, Punit Agrawal)" * tag 'pm-5.11-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: cpufreq: intel_pstate: Use most recent guaranteed performance values cpufreq: intel_pstate: Implement the ->adjust_perf() callback cpufreq: Add special-purpose fast-switching callback for drivers cpufreq: schedutil: Add util to struct sg_cpu cppc_cpufreq: replace per-cpu data array with a list cppc_cpufreq: expose information on frequency domains cppc_cpufreq: clarify support for coordination types cppc_cpufreq: use policy->cpu as driver of frequency setting ACPI: processor: fix NONE coordination for domain mapping failure

Merge branch 'pm-cpufreq'

2020-12-22T16:59:11Z

* pm-cpufreq: cpufreq: intel_pstate: Use most recent guaranteed performance values cpufreq: intel_pstate: Implement the ->adjust_perf() callback cpufreq: Add special-purpose fast-switching callback for drivers cpufreq: schedutil: Add util to struct sg_cpu cppc_cpufreq: replace per-cpu data array with a list cppc_cpufreq: expose information on frequency domains cppc_cpufreq: clarify support for coordination types cppc_cpufreq: use policy->cpu as driver of frequency setting ACPI: processor: fix NONE coordination for domain mapping failure ACPI: processor: Drop duplicate setting of shared_cpu_map

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

2020-12-20T18:44:05Z

Pull KVM updates from Paolo Bonzini: "Much x86 work was pushed out to 5.12, but ARM more than made up for it. ARM: - PSCI relay at EL2 when "protected KVM" is enabled - New exception injection code - Simplification of AArch32 system register handling - Fix PMU accesses when no PMU is enabled - Expose CSV3 on non-Meltdown hosts - Cache hierarchy discovery fixes - PV steal-time cleanups - Allow function pointers at EL2 - Various host EL2 entry cleanups - Simplification of the EL2 vector allocation s390: - memcg accouting for s390 specific parts of kvm and gmap - selftest for diag318 - new kvm_stat for when async_pf falls back to sync x86: - Tracepoints for the new pagetable code from 5.10 - Catch VFIO and KVM irqfd events before userspace - Reporting dirty pages to userspace with a ring buffer - SEV-ES host support - Nested VMX support for wait-for-SIPI activity state - New feature flag (AVX512 FP16) - New system ioctl to report Hyper-V-compatible paravirtualization features Generic: - Selftest improvements" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (171 commits) KVM: SVM: fix 32-bit compilation KVM: SVM: Add AP_JUMP_TABLE support in prep for AP booting KVM: SVM: Provide support to launch and run an SEV-ES guest KVM: SVM: Provide an updated VMRUN invocation for SEV-ES guests KVM: SVM: Provide support for SEV-ES vCPU loading KVM: SVM: Provide support for SEV-ES vCPU creation/loading KVM: SVM: Update ASID allocation to support SEV-ES guests KVM: SVM: Set the encryption mask for the SVM host save area KVM: SVM: Add NMI support for an SEV-ES guest KVM: SVM: Guest FPU state save/restore not needed for SEV-ES guest KVM: SVM: Do not report support for SMM for an SEV-ES guest KVM: x86: Update __get_sregs() / __set_sregs() to support SEV-ES KVM: SVM: Add support for CR8 write traps for an SEV-ES guest KVM: SVM: Add support for CR4 write traps for an SEV-ES guest KVM: SVM: Add support for CR0 write traps for an SEV-ES guest KVM: SVM: Add support for EFER write traps for an SEV-ES guest KVM: SVM: Support string IO operations for an SEV-ES guest KVM: SVM: Support MMIO for an SEV-ES guest KVM: SVM: Create trace events for VMGEXIT MSR protocol processing KVM: SVM: Create trace events for VMGEXIT processing ...

Merge tag 'pm-5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

2020-12-16T00:30:31Z

Pull power management updates from Rafael Wysocki: "These update cpufreq (core and drivers), cpuidle (polling state implementation and the PSCI driver), the OPP (operating performance points) framework, devfreq (core and drivers), the power capping RAPL (Running Average Power Limit) driver, the Energy Model support, the generic power domains (genpd) framework, the ACPI device power management, the core system-wide suspend code and power management utilities. Specifics: - Use local_clock() instead of jiffies in the cpufreq statistics to improve accuracy (Viresh Kumar). - Fix up OPP usage in the cpufreq-dt and qcom-cpufreq-nvmem cpufreq drivers (Viresh Kumar). - Clean up the cpufreq core, the intel_pstate driver and the schedutil cpufreq governor (Rafael Wysocki). - Fix up error code paths in the sti-cpufreq and mediatek cpufreq drivers (Yangtao Li, Qinglang Miao). - Fix cpufreq_online() to return error codes instead of success (0) in all cases when it fails (Wang ShaoBo). - Add mt8167 support to the mediatek cpufreq driver and blacklist mt8516 in the cpufreq-dt-platdev driver (Fabien Parent). - Modify the tegra194 cpufreq driver to always return values from the frequency table as the current frequency and clean up that driver (Sumit Gupta, Jon Hunter). - Modify the arm_scmi cpufreq driver to allow it to discover the power scale present in the performance protocol and provide this information to the Energy Model (Lukasz Luba). - Add missing MODULE_DEVICE_TABLE to several cpufreq drivers (Pali Rohár). - Clean up the CPPC cpufreq driver (Ionela Voinescu). - Fix NVMEM_IMX_OCOTP dependency in the imx cpufreq driver (Arnd Bergmann). - Rework the poling interval selection for the polling state in cpuidle (Mel Gorman). - Enable suspend-to-idle for PSCI OSI mode in the PSCI cpuidle driver (Ulf Hansson). - Modify the OPP framework to support empty (node-less) OPP tables in DT for passing dependency information (Nicola Mazzucato). - Fix potential lockdep issue in the OPP core and clean up the OPP core (Viresh Kumar). - Modify dev_pm_opp_put_regulators() to accept a NULL argument and update its users accordingly (Viresh Kumar). - Add frequency changes tracepoint to devfreq (Matthias Kaehlcke). - Add support for governor feature flags to devfreq, make devfreq sysfs file permissions depend on the governor and clean up the devfreq core (Chanwoo Choi). - Clean up the tegra20 devfreq driver and deprecate it to allow another driver based on EMC_STAT to be used instead of it (Dmitry Osipenko). - Add interconnect support to the tegra30 devfreq driver, allow it to take the interconnect and OPP information from DT and clean it up (Dmitry Osipenko). - Add interconnect support to the exynos-bus devfreq driver along with interconnect properties documentation (Sylwester Nawrocki). - Add suport for AMD Fam17h and Fam19h processors to the RAPL power capping driver (Victor Ding, Kim Phillips). - Fix handling of overly long constraint names in the powercap framework (Lukasz Luba). - Fix the wakeup configuration handling for bridges in the ACPI device power management core (Rafael Wysocki). - Add support for using an abstract scale for power units in the Energy Model (EM) and document it (Lukasz Luba). - Add em_cpu_energy() micro-optimization to the EM (Pavankumar Kondeti). - Modify the generic power domains (genpd) framwework to support suspend-to-idle (Ulf Hansson). - Fix creation of debugfs nodes in genpd (Thierry Strudel). - Clean up genpd (Lina Iyer). - Clean up the core system-wide suspend code and make it print driver flags for devices with debug enabled (Alex Shi, Patrice Chotard, Chen Yu). - Modify the ACPI system reboot code to make it prepare for system power off to avoid confusing the platform firmware (Kai-Heng Feng). - Update the pm-graph (multiple changes, mostly usability-related) and cpupower (online and offline CPU information support) PM utilities (Todd Brandt, Brahadambal Srinivasan)" * tag 'pm-5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (86 commits) cpufreq: Fix cpufreq_online() return value on errors cpufreq: Fix up several kerneldoc comments cpufreq: stats: Use local_clock() instead of jiffies cpufreq: schedutil: Simplify sugov_update_next_freq() cpufreq: intel_pstate: Simplify intel_cpufreq_update_pstate() PM: domains: create debugfs nodes when adding power domains opp: of: Allow empty opp-table with opp-shared dt-bindings: opp: Allow empty OPP tables media: venus: dev_pm_opp_put_*() accepts NULL argument drm/panfrost: dev_pm_opp_put_*() accepts NULL argument drm/lima: dev_pm_opp_put_*() accepts NULL argument PM / devfreq: exynos: dev_pm_opp_put_*() accepts NULL argument cpufreq: qcom-cpufreq-nvmem: dev_pm_opp_put_*() accepts NULL argument cpufreq: dt: dev_pm_opp_put_regulators() accepts NULL argument opp: Allow dev_pm_opp_put_*() APIs to accept NULL opp_table opp: Don't create an OPP table from dev_pm_opp_get_opp_table() cpufreq: dt: Don't (ab)use dev_pm_opp_get_opp_table() to create OPP table opp: Reduce the size of critical section in _opp_kref_release() PM / EM: Micro optimization in em_cpu_energy cpufreq: arm_scmi: Discover the power scale in performance protocol ...