linux/kernel/sched/syscalls.c, branch v6.19

sched: Deadline has dynamic priority

2026-01-15T20:57:53Z

While FIFO/RR have static priority, DEADLINE is a dynamic priority scheme. Notably it has static priority -1. Do not assume the priority doesn't change for deadline tasks just because the static priority doesn't change. This ensures DL always sees {DE,EN}QUEUE_MOVE where appropriate. Fixes: ff77e4685359 ("sched/rt: Fix PI handling vs. sched_setscheduler()") Signed-off-by: Peter Zijlstra (Intel) Tested-by: Pierre Gondois Tested-by: Juri Lelli Link: https://patch.msgid.link/20260114130528.GB831285@noisy.programming.kicks-ass.net

sched: Provide idle_rq() helper

2026-01-13T10:37:52Z

A fix for the dl_server 'requires' idle_cpu() usage, which made me note that it and available_idle_cpu() are extern function calls. And while idle_cpu() is used outside of kernel/sched/, available_idle_cpu() is not. This makes it hard to make idle_cpu() an inline helper, so provide idle_rq() and implement idle_cpu() and available_idle_cpu() using that. Signed-off-by: Peter Zijlstra (Intel)

Merge tag 'irq-core-2025-11-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2025-12-02T17:14:26Z

Pull irq core updates from Thomas Gleixner: "Updates for the interrupt core and treewide cleanups: - Rework of the Per Processor Interrupt (PPI) management on ARM[64] PPI support was built under the assumption that the systems are homogenous so that the same CPU local device types are connected to them. That's unfortunately wishful thinking and created horrible workarounds. This rework provides affinity management for PPIs so that they can be individually configured in the firmware tables and mops up the related drivers all over the place. - Prevent CPUSET/isolation changes to arbitrarily affine interrupt threads to random CPUs, which ignores user or driver settings. - Plug a harmless race in the interrupt affinity proc interface, which allows to see a half updated mask - Adjust the priority of secondary interrupt threads on RT, so that the combination of primary and secondary thread emulates the hardware interrupt plus thread scenario. Having them at the same priority can cause starvation issues in some drivers" * tag 'irq-core-2025-11-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (33 commits) genirq: Remove cpumask availability check on kthread affinity setting genirq: Fix interrupt threads affinity vs. cpuset isolated partitions genirq: Prevent early spurious wake-ups of interrupt threads genirq: Use raw_spinlock_irq() in irq_set_affinity_notifier() genirq/manage: Reduce priority of forced secondary interrupt handler genirq/proc: Fix race in show_irq_affinity() genirq: Fix percpu_devid irq affinity documentation perf: arm_pmu: Kill last use of per-CPU cpu_armpmu pointer irqdomain: Kill of_node_to_fwnode() helper genirq: Kill irq_{g,s}et_percpu_devid_partition() irqchip: Kill irq-partition-percpu irqchip/apple-aic: Drop support for custom PMU irq partitions irqchip/gic-v3: Drop support for custom PPI partitions coresight: trbe: Request specific affinities for per CPU interrupts perf: arm_spe_pmu: Request specific affinities for per CPU interrupts perf: arm_pmu: Request specific affinities for per CPU NMIs/interrupts genirq: Add request_percpu_irq_affinity() helper genirq: Allow per-cpu interrupt sharing for non-overlapping affinities genirq: Update request_percpu_nmi() to take an affinity genirq: Add affinity to percpu_devid interrupt requests ...

sched/proxy: Yield the donor task

2025-11-11T11:33:36Z

When executing a task in proxy context, handle yields as if they were requested by the donor task. This matches the traditional PI semantics of yield() as well. This avoids scenario like proxy task yielding, pick next task selecting the same previous blocked donor, running the proxy task again, etc. Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202510211205.1e0f5223-lkp@intel.com Suggested-by: Peter Zijlstra Signed-off-by: Fernand Sieber Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20251106104022.195157-1-sieberf@amazon.com

genirq/manage: Reduce priority of forced secondary interrupt handler

2025-11-01T20:30:02Z

Crystal reports that the PCIe Advanced Error Reporting driver gets stuck in an infinite loop on PREEMPT_RT: Both the primary interrupt handler aer_irq() as well as the secondary handler aer_isr() are forced into threads with identical priority. Crystal writes that on the ARM system in question, the primary handler has to clear an error in the Root Error Status register... "before the next error happens, or else the hardware will set the Multiple ERR_COR Received bit. If that bit is set, then aer_isr() can't rely on the Error Source Identification register, so it scans through all devices looking for errors -- and for some reason, on this system, accessing the AER registers (or any Config Space above 0x400, even though there are capabilities located there) generates an Unsupported Request Error (but returns valid data). Since this happens more than once, without aer_irq() preempting, it causes another multi error and we get stuck in a loop." The issue does not show on non-PREEMPT_RT because the primary handler runs in hardirq context and thus can preempt the threaded secondary handler, clear the Root Error Status register and prevent the secondary handler from getting stuck. Emulate the same behavior on PREEMPT_RT by assigning a lower default priority to the secondary handler if the primary handler is forced into a thread. Reported-by: Crystal Wood Signed-off-by: Lukas Wunner Signed-off-by: Thomas Gleixner Tested-by: Crystal Wood Reviewed-by: Sebastian Andrzej Siewior Link: https://patch.msgid.link/f6dcdb41be2694886b8dbf4fe7b3ab89e9d5114c.1761569303.git.lukas@wunner.de Closes: https://lore.kernel.org/r/20250902224441.368483-1-crwood@redhat.com/

sched: Cleanup the sched_change NOCLOCK usage

2025-10-16T09:13:54Z

Teach the sched_change pattern how to do update_rq_clock(); this allows for some simplifications / cleanups. Suggested-by: K Prateek Nayak Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Juri Lelli Acked-by: Tejun Heo Acked-by: Vincent Guittot

sched: Move sched_class::prio_changed() into the change pattern

2025-10-16T09:13:52Z

Move sched_class::prio_changed() into the change pattern. And while there, extend it with sched_class::get_prio() in order to fix the deadline sitation. Suggested-by: Tejun Heo Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Juri Lelli Acked-by: Tejun Heo Acked-by: Vincent Guittot

sched: Cleanup sched_delayed handling for class switches

2025-10-16T09:13:51Z

Use the new sched_class::switching_from() method to dequeue delayed tasks before switching to another class. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Vincent Guittot Reviewed-by: Juri Lelli Acked-by: Tejun Heo

sched: Fold sched_class::switch{ing,ed}_{to,from}() into the change pattern

2025-10-16T09:13:51Z

Add {DE,EN}QUEUE_CLASS and fold the sched_class::switch* methods into the change pattern. This completes and makes the pattern more symmetric. This changes the order of callbacks slightly: OLD NEW | | switching_from() dequeue_task(); | dequeue_task() put_prev_task(); | put_prev_task() | switched_from() | ... change task ... | ... change task ... | switching_to(); | switching_to() enqueue_task(); | enqueue_task() set_next_task(); | set_next_task() prev_class->switched_from() | switched_to() | switched_to() | Notably, it moves the switched_from() callback right after the dequeue/put. Existing implementations don't appear to be affected by this change in location -- specifically the task isn't enqueued on the class in question in either location. Make (CLASS)^(SAVE|MOVE), because there is nothing to save-restore when changing scheduling classes. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Juri Lelli Acked-by: Tejun Heo Acked-by: Vincent Guittot

sched: Employ sched_change guards

2025-10-16T09:13:50Z

As proposed a long while ago -- and half done by scx -- wrap the scheduler's 'change' pattern in a guard helper. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Juri Lelli Acked-by: Tejun Heo Acked-by: Vincent Guittot