diff options
| author | Andrea Righi <arighi@nvidia.com> | 2025-07-05 07:43:51 +0200 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2025-07-17 08:19:38 -1000 |
| commit | 06efc9fe0b8deeb83b47fd7c5451fe1a60c8a761 (patch) | |
| tree | a86d51a455e72054f59a3d78e8a1a2b39543111f | |
| parent | e14fd98c6d66cb76694b12c05768e4f9e8c95664 (diff) | |
sched_ext: idle: Handle migration-disabled tasks in idle selection
When SCX_OPS_ENQ_MIGRATION_DISABLED is enabled, migration-disabled tasks
are also routed to ops.enqueue(). A scheduler may attempt to dispatch
such tasks directly to an idle CPU using the default idle selection
policy via scx_bpf_select_cpu_and() or scx_bpf_select_cpu_dfl().
This scenario must be properly handled by the built-in idle policy to
avoid returning an idle CPU where the target task isn't allowed to run.
Otherwise, it can lead to errors such as:
EXIT: runtime error (SCX_DSQ_LOCAL[_ON] cannot move migration disabled Chrome_ChildIOT[291646] from CPU 3 to 14)
Prevent this by explicitly handling migration-disabled tasks in the
built-in idle selection logic, maintaining their CPU affinity.
Fixes: a730e3f7a48bc ("sched_ext: idle: Consolidate default idle CPU selection kfuncs")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
| -rw-r--r-- | kernel/sched/ext_idle.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched/ext_idle.c b/kernel/sched/ext_idle.c index 6d29d3cbc670..001fb88a8481 100644 --- a/kernel/sched/ext_idle.c +++ b/kernel/sched/ext_idle.c @@ -903,7 +903,7 @@ s32 select_cpu_from_kfunc(struct task_struct *p, s32 prev_cpu, u64 wake_flags, * selection optimizations and simply check whether the previously * used CPU is idle and within the allowed cpumask. */ - if (p->nr_cpus_allowed == 1) { + if (p->nr_cpus_allowed == 1 || is_migration_disabled(p)) { if (cpumask_test_cpu(prev_cpu, allowed ?: p->cpus_ptr) && scx_idle_test_and_clear_cpu(prev_cpu)) cpu = prev_cpu; |