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| author |   Tejun Heo <tj@kernel.org> | 2025-01-24 10:48:25 -1000 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2025-01-24 10:48:25 -1000 |
| commit | e9fe182772dcb2630964724fd93e9c90b68ea0fd (patch) | |
| tree | 190d0cfd51c1eee4830f0f4bc0095f34796d6234 | |
| parent | selftests/sched_ext: Fix enum resolution (diff) | |
| download | wireguard-linux-e9fe182772dcb2630964724fd93e9c90b68ea0fd.tar.xz wireguard-linux-e9fe182772dcb2630964724fd93e9c90b68ea0fd.zip | |
sched_ext: selftests/dsp_local_on: Fix sporadic failures
dsp_local_on has several incorrect assumptions, one of which is that
p->nr_cpus_allowed always tracks p->cpus_ptr. This is not true when a task
is scheduled out while migration is disabled - p->cpus_ptr is temporarily
overridden to the previous CPU while p->nr_cpus_allowed remains unchanged.
This led to sporadic test faliures when dsp_local_on_dispatch() tries to put
a migration disabled task to a different CPU. Fix it by keeping the previous
CPU when migration is disabled.
There are SCX schedulers that make use of p->nr_cpus_allowed. They should
also implement explicit handling for p->migration_disabled.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Ihor Solodrai <ihor.solodrai@pm.me>
Cc: Andrea Righi <arighi@nvidia.com>
Cc: Changwoo Min <changwoo@igalia.com>
Diffstat (limited to '')
| -rw-r--r-- | tools/testing/selftests/sched_ext/dsp_local_on.bpf.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/tools/testing/selftests/sched_ext/dsp_local_on.bpf.c b/tools/testing/selftests/sched_ext/dsp_local_on.bpf.c index fbda6bf54671..758b479bd1ee 100644 --- a/tools/testing/selftests/sched_ext/dsp_local_on.bpf.c +++ b/tools/testing/selftests/sched_ext/dsp_local_on.bpf.c @@ -43,7 +43,7 @@ void BPF_STRUCT_OPS(dsp_local_on_dispatch, s32 cpu, struct task_struct *prev) if (!p) return; - if (p->nr_cpus_allowed == nr_cpus) + if (p->nr_cpus_allowed == nr_cpus && !p->migration_disabled) target = bpf_get_prandom_u32() % nr_cpus; else target = scx_bpf_task_cpu(p); |