github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-07-27 01:32:21 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

tools/sched_ext: Handle migration-disabled tasks in scx_central

Browse Source 
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>
This commit is contained in:
Cheng-Yang Chou 2026-04-13 15:19:59 +08:00 committed by Tejun Heo
parent 1d2c535315
commit 7c7bb206e8
1 changed files with 7 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
tools/sched_ext/scx_central.bpf.c
View File

@ -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);