linux/kernel/sched, branch v5.14

sched: Fix get_push_task() vs migrate_disable()

2021-08-26T17:02:00Z

push_rt_task() attempts to move the currently running task away if the next runnable task has migration disabled and therefore is pinned on the current CPU. The current task is retrieved via get_push_task() which only checks for nr_cpus_allowed == 1, but does not check whether the task has migration disabled and therefore cannot be moved either. The consequence is a pointless invocation of the migration thread which correctly observes that the task cannot be moved. Return NULL if the task has migration disabled and cannot be moved to another CPU. Fixes: a7c81556ec4d3 ("sched: Fix migrate_disable() vs rt/dl balancing") Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20210826133738.yiotqbtdaxzjsnfj@linutronix.de

sched: Fix Core-wide rq->lock for uninitialized CPUs

2021-08-20T10:32:53Z

Eugene tripped over the case where rq_lock(), as called in a for_each_possible_cpu() loop came apart because rq->core hadn't been setup yet. This is a somewhat unusual, but valid case. Rework things such that rq->core is initialized to point at itself. IOW initialize each CPU as a single threaded Core. CPU online will then join the new CPU (thread) to an existing Core where needed. For completeness sake, have CPU offline fully undo the state so as to not presume the topology will match the next time it comes online. Fixes: 9edeaea1bc45 ("sched: Core-wide rq->lock") Reported-by: Eugene Syromiatnikov Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Josh Don Tested-by: Eugene Syromiatnikov Link: https://lkml.kernel.org/r/YR473ZGeKqMs6kw+@hirez.programming.kicks-ass.net

sched/rt: Fix double enqueue caused by rt_effective_prio

2021-08-04T13:16:31Z

Double enqueues in rt runqueues (list) have been reported while running a simple test that spawns a number of threads doing a short sleep/run pattern while being concurrently setscheduled between rt and fair class. WARNING: CPU: 3 PID: 2825 at kernel/sched/rt.c:1294 enqueue_task_rt+0x355/0x360 CPU: 3 PID: 2825 Comm: setsched__13 RIP: 0010:enqueue_task_rt+0x355/0x360 Call Trace: __sched_setscheduler+0x581/0x9d0 _sched_setscheduler+0x63/0xa0 do_sched_setscheduler+0xa0/0x150 __x64_sys_sched_setscheduler+0x1a/0x30 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xae list_add double add: new=ffff9867cb629b40, prev=ffff9867cb629b40, next=ffff98679fc67ca0. kernel BUG at lib/list_debug.c:31! invalid opcode: 0000 [#1] PREEMPT_RT SMP PTI CPU: 3 PID: 2825 Comm: setsched__13 RIP: 0010:__list_add_valid+0x41/0x50 Call Trace: enqueue_task_rt+0x291/0x360 __sched_setscheduler+0x581/0x9d0 _sched_setscheduler+0x63/0xa0 do_sched_setscheduler+0xa0/0x150 __x64_sys_sched_setscheduler+0x1a/0x30 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xae __sched_setscheduler() uses rt_effective_prio() to handle proper queuing of priority boosted tasks that are setscheduled while being boosted. rt_effective_prio() is however called twice per each __sched_setscheduler() call: first directly by __sched_setscheduler() before dequeuing the task and then by __setscheduler() to actually do the priority change. If the priority of the pi_top_task is concurrently being changed however, it might happen that the two calls return different results. If, for example, the first call returned the same rt priority the task was running at and the second one a fair priority, the task won't be removed by the rt list (on_list still set) and then enqueued in the fair runqueue. When eventually setscheduled back to rt it will be seen as enqueued already and the WARNING/BUG be issued. Fix this by calling rt_effective_prio() only once and then reusing the return value. While at it refactor code as well for clarity. Concurrent priority inheritance handling is still safe and will eventually converge to a new state by following the inheritance chain(s). Fixes: 0782e63bc6fe ("sched: Handle priority boosted tasks proper in setscheduler()") [squashed Peterz changes; added changelog] Reported-by: Mark Simmons Signed-off-by: Juri Lelli Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20210803104501.38333-1-juri.lelli@redhat.com

Merge tag 'sched-urgent-2021-07-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2021-07-11T18:13:57Z

Pull scheduler fixes from Ingo Molnar: "Three fixes: - Fix load tracking bug/inconsistency - Fix a sporadic CFS bandwidth constraints enforcement bug - Fix a uclamp utilization tracking bug for newly woken tasks" * tag 'sched-urgent-2021-07-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/uclamp: Ignore max aggregation if rq is idle sched/fair: Fix CFS bandwidth hrtimer expiry type sched/fair: Sync load_sum with load_avg after dequeue

Merge tag 'pm-5.14-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

2021-07-07T20:22:59Z

Pull more power management updates from Rafael Wysocki: "These include cpufreq core simplifications and fixes, cpufreq driver updates, cpuidle driver update, a generic power domains (genpd) locking fix and a debug-related simplification of the PM core. Specifics: - Drop the ->stop_cpu() (not really useful) and ->resolve_freq() (unused) cpufreq driver callbacks and modify the users of the former accordingly (Viresh Kumar, Rafael Wysocki). - Add frequency invariance support to the ACPI CPPC cpufreq driver again along with the related fixes and cleanups (Viresh Kumar). - Update the Meditak, qcom and SCMI ARM cpufreq drivers (Fabien Parent, Seiya Wang, Sibi Sankar, Christophe JAILLET). - Rename black/white-lists in the DT cpufreq driver (Viresh Kumar). - Add generic performance domains support to the dvfs DT bindings (Sudeep Holla). - Refine locking in the generic power domains (genpd) support code to avoid lock dependency issues (Stephen Boyd). - Update the MSM and qcom ARM cpuidle drivers (Bartosz Dudziak). - Simplify the PM core debug code by using ktime_us_delta() to compute time interval lengths (Mark-PK Tsai)" * tag 'pm-5.14-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (21 commits) PM: domains: Shrink locking area of the gpd_list_lock PM: sleep: Use ktime_us_delta() in initcall_debug_report() cpufreq: CPPC: Add support for frequency invariance arch_topology: Avoid use-after-free for scale_freq_data cpufreq: CPPC: Pass structure instance by reference cpufreq: CPPC: Fix potential memleak in cppc_cpufreq_cpu_init cpufreq: Remove ->resolve_freq() cpufreq: Reuse cpufreq_driver_resolve_freq() in __cpufreq_driver_target() cpufreq: Remove the ->stop_cpu() driver callback cpufreq: powernv: Migrate to ->exit() callback instead of ->stop_cpu() cpufreq: CPPC: Migrate to ->exit() callback instead of ->stop_cpu() cpufreq: intel_pstate: Combine ->stop_cpu() and ->offline() cpuidle: qcom: Add SPM register data for MSM8226 dt-bindings: arm: msm: Add SAW2 for MSM8226 dt-bindings: cpufreq: update cpu type and clock name for MT8173 SoC clk: mediatek: remove deprecated CLK_INFRA_CA57SEL for MT8173 SoC cpufreq: dt: Rename black/white-lists cpufreq: scmi: Fix an error message cpufreq: mediatek: add support for mt8365 dt-bindings: dvfs: Add support for generic performance domains ...

sched/uclamp: Ignore max aggregation if rq is idle

2021-07-02T13:58:24Z

When a task wakes up on an idle rq, uclamp_rq_util_with() would max aggregate with rq value. But since there is no task enqueued yet, the values are stale based on the last task that was running. When the new task actually wakes up and enqueued, then the rq uclamp values should reflect that of the newly woken up task effective uclamp values. This is a problem particularly for uclamp_max because it default to 1024. If a task p with uclamp_max = 512 wakes up, then max aggregation would ignore the capping that should apply when this task is enqueued, which is wrong. Fix that by ignoring max aggregation if the rq is idle since in that case the effective uclamp value of the rq will be the ones of the task that will wake up. Fixes: 9d20ad7dfc9a ("sched/uclamp: Add uclamp_util_with()") Signed-off-by: Xuewen Yan Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Valentin Schneider [qias: Changelog] Reviewed-by: Qais Yousef Link: https://lore.kernel.org/r/20210630141204.8197-1-xuewen.yan94@gmail.com

sched/fair: Fix CFS bandwidth hrtimer expiry type

2021-07-02T13:58:24Z

The time remaining until expiry of the refresh_timer can be negative. Casting the type to an unsigned 64-bit value will cause integer underflow, making the runtime_refresh_within return false instead of true. These situations are rare, but they do happen. This does not cause user-facing issues or errors; other than possibly unthrottling cfs_rq's using runtime from the previous period(s), making the CFS bandwidth enforcement less strict in those (special) situations. Signed-off-by: Odin Ugedal Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Ben Segall Link: https://lore.kernel.org/r/20210629121452.18429-1-odin@uged.al

sched/fair: Sync load_sum with load_avg after dequeue

2021-07-02T13:58:23Z

commit 9e077b52d86a ("sched/pelt: Check that *_avg are null when *_sum are") reported some inconsitencies between *_avg and *_sum. commit 1c35b07e6d39 ("sched/fair: Ensure _sum and _avg values stay consistent") fixed some but one remains when dequeuing load. sync the cfs's load_sum with its load_avg after dequeuing the load of a sched_entity. Fixes: 9e077b52d86a ("sched/pelt: Check that *_avg are null when *_sum are") Reported-by: Sachin Sant Signed-off-by: Vincent Guittot Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Odin Ugedal Tested-by: Sachin Sant Link: https://lore.kernel.org/r/20210701171837.32156-1-vincent.guittot@linaro.org

Merge branch 'for-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2021-07-02T00:22:14Z

Pull cgroup updates from Tejun Heo: - cgroup.kill is added which implements atomic killing of the whole subtree. Down the line, this should be able to replace the multiple userland implementations of "keep killing till empty". - PSI can now be turned off at boot time to avoid overhead for configurations which don't care about PSI. * 'for-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: make per-cgroup pressure stall tracking configurable cgroup: Fix kernel-doc cgroup: inline cgroup_task_freeze() tests/cgroup: test cgroup.kill tests/cgroup: move cg_wait_for(), cg_prepare_for_wait() tests/cgroup: use cgroup.kill in cg_killall() docs/cgroup: add entry for cgroup.kill cgroup: introduce cgroup.kill

cpufreq: CPPC: Add support for frequency invariance

2021-07-01T02:02:14Z

The Frequency Invariance Engine (FIE) is providing a frequency scaling correction factor that helps achieve more accurate load-tracking. Normally, this scaling factor can be obtained directly with the help of the cpufreq drivers as they know the exact frequency the hardware is running at. But that isn't the case for CPPC cpufreq driver. Another way of obtaining that is using the arch specific counter support, which is already present in kernel, but that hardware is optional for platforms. This patch updates the CPPC driver to register itself with the topology core to provide its own implementation (cppc_scale_freq_tick()) of topology_scale_freq_tick() which gets called by the scheduler on every tick. Note that the arch specific counters have higher priority than CPPC counters, if available, though the CPPC driver doesn't need to have any special handling for that. On an invocation of cppc_scale_freq_tick(), we schedule an irq work (since we reach here from hard-irq context), which then schedules a normal work item and cppc_scale_freq_workfn() updates the per_cpu arch_freq_scale variable based on the counter updates since the last tick. To allow platforms to disable this CPPC counter-based frequency invariance support, this is all done under CONFIG_ACPI_CPPC_CPUFREQ_FIE, which is enabled by default. This also exports sched_setattr_nocheck() as the CPPC driver can be built as a module. Cc: linux-acpi@vger.kernel.org Tested-by: Vincent Guittot Reviewed-by: Ionela Voinescu Tested-by: Qian Cai Signed-off-by: Viresh Kumar