Patch "sched/fair: Take the scheduling domain into account in select_idle_core()" has been added to the 6.8-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    sched/fair: Take the scheduling domain into account in select_idle_core()

to the 6.8-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     sched-fair-take-the-scheduling-domain-into-account-i.patch
and it can be found in the queue-6.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 5f73f09733cd06244fcebc93073324423f5e8844
Author: Keisuke Nishimura <keisuke.nishimura@xxxxxxxx>
Date:   Wed Jan 10 14:17:07 2024 +0100

    sched/fair: Take the scheduling domain into account in select_idle_core()
    
    [ Upstream commit 23d04d8c6b8ec339057264659b7834027f3e6a63 ]
    
    When picking a CPU on task wakeup, select_idle_core() has to take
    into account the scheduling domain where the function looks for the CPU.
    
    This is because the "isolcpus" kernel command line option can remove CPUs
    from the domain to isolate them from other SMT siblings.
    
    This change replaces the set of CPUs allowed to run the task from
    p->cpus_ptr by the intersection of p->cpus_ptr and sched_domain_span(sd)
    which is stored in the 'cpus' argument provided by select_idle_cpu().
    
    Fixes: 9fe1f127b913 ("sched/fair: Merge select_idle_core/cpu()")
    Signed-off-by: Keisuke Nishimura <keisuke.nishimura@xxxxxxxx>
    Signed-off-by: Julia Lawall <julia.lawall@xxxxxxxx>
    Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20240110131707.437301-2-keisuke.nishimura@xxxxxxxx
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 66457d4b8965c..e2b4e0396af84 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7289,7 +7289,7 @@ static int select_idle_core(struct task_struct *p, int core, struct cpumask *cpu
 		if (!available_idle_cpu(cpu)) {
 			idle = false;
 			if (*idle_cpu == -1) {
-				if (sched_idle_cpu(cpu) && cpumask_test_cpu(cpu, p->cpus_ptr)) {
+				if (sched_idle_cpu(cpu) && cpumask_test_cpu(cpu, cpus)) {
 					*idle_cpu = cpu;
 					break;
 				}
@@ -7297,7 +7297,7 @@ static int select_idle_core(struct task_struct *p, int core, struct cpumask *cpu
 			}
 			break;
 		}
-		if (*idle_cpu == -1 && cpumask_test_cpu(cpu, p->cpus_ptr))
+		if (*idle_cpu == -1 && cpumask_test_cpu(cpu, cpus))
 			*idle_cpu = cpu;
 	}