linux/kernel/cpu.c, branch v5.6

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

2020-01-28T18:07:09Z

Pull scheduler updates from Ingo Molnar: "These were the main changes in this cycle: - More -rt motivated separation of CONFIG_PREEMPT and CONFIG_PREEMPTION. - Add more low level scheduling topology sanity checks and warnings to filter out nonsensical topologies that break scheduling. - Extend uclamp constraints to influence wakeup CPU placement - Make the RT scheduler more aware of asymmetric topologies and CPU capacities, via uclamp metrics, if CONFIG_UCLAMP_TASK=y - Make idle CPU selection more consistent - Various fixes, smaller cleanups, updates and enhancements - please see the git log for details" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (58 commits) sched/fair: Define sched_idle_cpu() only for SMP configurations sched/topology: Assert non-NUMA topology masks don't (partially) overlap idle: fix spelling mistake "iterrupts" -> "interrupts" sched/fair: Remove redundant call to cpufreq_update_util() sched/psi: create /proc/pressure and /proc/pressure/{io|memory|cpu} only when psi enabled sched/fair: Fix sgc->{min,max}_capacity calculation for SD_OVERLAP sched/fair: calculate delta runnable load only when it's needed sched/cputime: move rq parameter in irqtime_account_process_tick stop_machine: Make stop_cpus() static sched/debug: Reset watchdog on all CPUs while processing sysrq-t sched/core: Fix size of rq::uclamp initialization sched/uclamp: Fix a bug in propagating uclamp value in new cgroups sched/fair: Load balance aggressively for SCHED_IDLE CPUs sched/fair : Improve update_sd_pick_busiest for spare capacity case watchdog: Remove soft_lockup_hrtimer_cnt and related code sched/rt: Make RT capacity-aware sched/fair: Make EAS wakeup placement consider uclamp restrictions sched/fair: Make task_fits_capacity() consider uclamp restrictions sched/uclamp: Rename uclamp_util_with() into uclamp_rq_util_with() sched/uclamp: Make uclamp util helpers use and return UL values ...

cpu/SMT: Fix x86 link error without CONFIG_SYSFS

2020-01-09T16:31:45Z

When CONFIG_SYSFS is disabled, but CONFIG_HOTPLUG_SMT is enabled, the kernel fails to link: arch/x86/power/cpu.o: In function `hibernate_resume_nonboot_cpu_disable': (.text+0x38d): undefined reference to `cpuhp_smt_enable' arch/x86/power/hibernate.o: In function `arch_resume_nosmt': hibernate.c:(.text+0x291): undefined reference to `cpuhp_smt_enable' hibernate.c:(.text+0x29c): undefined reference to `cpuhp_smt_disable' Move the exported functions out of the #ifdef section into its own with the correct conditions. The patch that caused this is marked for stable backports, so this one may need to be backported as well. Fixes: ec527c318036 ("x86/power: Fix 'nosmt' vs hibernation triple fault during resume") Signed-off-by: Arnd Bergmann Signed-off-by: Thomas Gleixner Reviewed-by: Jiri Kosina Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20191210195614.786555-1-arnd@arndb.de

cpu/hotplug, stop_machine: Fix stop_machine vs hotplug order

2019-12-17T12:32:50Z

Paul reported a very sporadic, rcutorture induced, workqueue failure. When the planets align, the workqueue rescuer's self-migrate fails and then triggers a WARN for running a work on the wrong CPU. Tejun then figured that set_cpus_allowed_ptr()'s stop_one_cpu() call could be ignored! When stopper->enabled is false, stop_machine will insta complete the work, without actually doing the work. Worse, it will not WARN about this (we really should fix this). It turns out there is a small window where a freshly online'ed CPU is marked 'online' but doesn't yet have the stopper task running: BP AP bringup_cpu() __cpu_up(cpu, idle) --> start_secondary() ... cpu_startup_entry() bringup_wait_for_ap() wait_for_ap_thread() <-- cpuhp_online_idle() while (1) do_idle() ... available to run kthreads ... stop_machine_unpark() stopper->enable = true; Close this by moving the stop_machine_unpark() into cpuhp_online_idle(), such that the stopper thread is ready before we start the idle loop and schedule. Reported-by: "Paul E. McKenney" Debugged-by: Tejun Heo Signed-off-by: Peter Zijlstra (Intel) Tested-by: "Paul E. McKenney"

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

2019-11-27T00:02:40Z

Pull locking updates from Ingo Molnar: "The main changes in this cycle were: - A comprehensive rewrite of the robust/PI futex code's exit handling to fix various exit races. (Thomas Gleixner et al) - Rework the generic REFCOUNT_FULL implementation using atomic_fetch_* operations so that the performance impact of the cmpxchg() loops is mitigated for common refcount operations. With these performance improvements the generic implementation of refcount_t should be good enough for everybody - and this got confirmed by performance testing, so remove ARCH_HAS_REFCOUNT and REFCOUNT_FULL entirely, leaving the generic implementation enabled unconditionally. (Will Deacon) - Other misc changes, fixes, cleanups" * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits) lkdtm: Remove references to CONFIG_REFCOUNT_FULL locking/refcount: Remove unused 'refcount_error_report()' function locking/refcount: Consolidate implementations of refcount_t locking/refcount: Consolidate REFCOUNT_{MAX,SATURATED} definitions locking/refcount: Move saturation warnings out of line locking/refcount: Improve performance of generic REFCOUNT_FULL code locking/refcount: Move the bulk of the REFCOUNT_FULL implementation into the header locking/refcount: Remove unused refcount_*_checked() variants locking/refcount: Ensure integer operands are treated as signed locking/refcount: Define constants for saturation and max refcount values futex: Prevent exit livelock futex: Provide distinct return value when owner is exiting futex: Add mutex around futex exit futex: Provide state handling for exec() as well futex: Sanitize exit state handling futex: Mark the begin of futex exit explicitly futex: Set task::futex_state to DEAD right after handling futex exit futex: Split futex_mm_release() for exit/exec exit/exec: Seperate mm_release() futex: Replace PF_EXITPIDONE with a state ...

cpu/speculation: Uninline and export CPU mitigations helpers

2019-11-04T11:22:02Z

A kernel module may need to check the value of the "mitigations=" kernel command line parameter as part of its setup when the module needs to perform software mitigations for a CPU flaw. Uninline and export the helper functions surrounding the cpu_mitigations enum to allow for their usage from a module. Lastly, privatize the enum and cpu_mitigations variable since the value of cpu_mitigations can be checked with the exported helper functions. Signed-off-by: Tyler Hicks Signed-off-by: Paolo Bonzini Signed-off-by: Thomas Gleixner

locking/lockdep: Remove unused @nested argument from lock_release()

2019-10-09T10:46:10Z

Since the following commit: b4adfe8e05f1 ("locking/lockdep: Remove unused argument in __lock_release") @nested is no longer used in lock_release(), so remove it from all lock_release() calls and friends. Signed-off-by: Qian Cai Signed-off-by: Peter Zijlstra (Intel) Acked-by: Will Deacon Acked-by: Daniel Vetter Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: airlied@linux.ie Cc: akpm@linux-foundation.org Cc: alexander.levin@microsoft.com Cc: daniel@iogearbox.net Cc: davem@davemloft.net Cc: dri-devel@lists.freedesktop.org Cc: duyuyang@gmail.com Cc: gregkh@linuxfoundation.org Cc: hannes@cmpxchg.org Cc: intel-gfx@lists.freedesktop.org Cc: jack@suse.com Cc: jlbec@evilplan.or Cc: joonas.lahtinen@linux.intel.com Cc: joseph.qi@linux.alibaba.com Cc: jslaby@suse.com Cc: juri.lelli@redhat.com Cc: maarten.lankhorst@linux.intel.com Cc: mark@fasheh.com Cc: mhocko@kernel.org Cc: mripard@kernel.org Cc: ocfs2-devel@oss.oracle.com Cc: rodrigo.vivi@intel.com Cc: sean@poorly.run Cc: st@kernel.org Cc: tj@kernel.org Cc: tytso@mit.edu Cc: vdavydov.dev@gmail.com Cc: vincent.guittot@linaro.org Cc: viro@zeniv.linux.org.uk Link: https://lkml.kernel.org/r/1568909380-32199-1-git-send-email-cai@lca.pw Signed-off-by: Ingo Molnar

cpu/SMT: create and export cpu_smt_possible()

2019-09-24T11:37:28Z

KVM needs to know if SMT is theoretically possible, this means it is supported and not forcefully disabled ('nosmt=force'). Create and export cpu_smt_possible() answering this question. Signed-off-by: Vitaly Kuznetsov Signed-off-by: Paolo Bonzini

cpu/hotplug: Cache number of online CPUs

2019-07-25T13:48:01Z

Re-evaluating the bitmap wheight of the online cpus bitmap in every invocation of num_online_cpus() over and over is a pretty useless exercise. Especially when num_online_cpus() is used in code paths like the IPI delivery of x86 or the membarrier code. Cache the number of online CPUs in the core and just return the cached variable. The accessor function provides only a snapshot when used without protection against concurrent CPU hotplug. The storage needs to use an atomic_t because the kexec and reboot code (ab)use set_cpu_online() in their 'shutdown' handlers without any form of serialization as pointed out by Mathieu. Regular CPU hotplug usage is properly serialized. Signed-off-by: Thomas Gleixner Reviewed-by: Mathieu Desnoyers Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1907091622590.1634@nanos.tec.linutronix.de

smp/hotplug: Track booted once CPUs in a cpumask

2019-07-25T13:47:37Z

The booted once information which is required to deal with the MCE broadcast issue on X86 correctly is stored in the per cpu hotplug state, which is perfectly fine for the intended purpose. X86 needs that information for supporting NMI broadcasting via shortcuts, but retrieving it from per cpu data is cumbersome. Move it to a cpumask so the information can be checked against the cpu_present_mask quickly. No functional change intended. Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20190722105219.818822855@linutronix.de

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

2019-07-08T17:39:56Z

Pull SMP/hotplug updates from Thomas Gleixner: "A small set of updates for SMP and CPU hotplug: - Abort disabling secondary CPUs in the freezer when a wakeup is pending instead of evaluating it only after all CPUs have been offlined. - Remove the shared annotation for the strict per CPU cfd_data in the smp function call core code. - Remove the return values of smp_call_function() and on_each_cpu() as they are unconditionally 0. Fixup the few callers which actually bothered to check the return value" * 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: smp: Remove smp_call_function() and on_each_cpu() return values smp: Do not mark call_function_data as shared cpu/hotplug: Abort disabling secondary CPUs if wakeup is pending cpu/hotplug: Fix notify_cpu_starting() reference in bringup_wait_for_ap()