diff options
| author | Cheng-Yang Chou <yphbchou0911@gmail.com> | 2026-04-13 10:19:59 +0300 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2026-04-17 21:32:07 +0300 |
| commit | 7c7bb206e87de48144e5c7249e2f7b7352f252e2 (patch) | |
| tree | c6abceaf7a59398fed67a71fdc6ca8c8d6d0b18c | |
| parent | 1d2c5353152d2e937a24b08261591c198996d13d (diff) | |
| download | linux-7c7bb206e87de48144e5c7249e2f7b7352f252e2.tar.xz | |
tools/sched_ext: Handle migration-disabled tasks in scx_central
When a task calls migrate_disable(), p->cpus_ptr is not updated until
migrate_disable_switch() runs during context switch, so dispatch_to_cpu()
may dequeue such a task and dispatch it to a CPU it cannot run on.
Extend the mismatch check in dispatch_to_cpu() to also test
is_migration_disabled() alongside the cpumask check, so tasks in this
window are bounced to the fallback DSQ.
Suggested-by: Andrea Righi <arighi@nvidia.com>
Suggested-by: Tejun Heo <tj@kernel.org>
Suggested-by: Kuba Piecuch <jpiecuch@google.com>
Signed-off-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Reviewed-by: Kuba Piecuch <jpiecuch@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
| -rw-r--r-- | tools/sched_ext/scx_central.bpf.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/tools/sched_ext/scx_central.bpf.c b/tools/sched_ext/scx_central.bpf.c index 4efcce099bd5..64dd60b3e922 100644 --- a/tools/sched_ext/scx_central.bpf.c +++ b/tools/sched_ext/scx_central.bpf.c @@ -149,10 +149,14 @@ static bool dispatch_to_cpu(s32 cpu) } /* - * If we can't run the task at the top, do the dumb thing and - * bounce it to the fallback dsq. + * If we can't run the task at the top for whatever reason, + * bounce it to the fallback dsq. Also check + * is_migration_disabled() explicitly as p->cpus_ptr may not + * reflect the migration-disabled state yet if + * migrate_disable_switch() hasn't run. */ - if (!bpf_cpumask_test_cpu(cpu, p->cpus_ptr)) { + if (!bpf_cpumask_test_cpu(cpu, p->cpus_ptr) || + (is_migration_disabled(p) && scx_bpf_task_cpu(p) != cpu)) { __sync_fetch_and_add(&nr_mismatches, 1); scx_bpf_dsq_insert(p, FALLBACK_DSQ_ID, SCX_SLICE_INF, 0); bpf_task_release(p); |