From: Joel Fernandes <joelagnelf@xxxxxxxxxx>
Hotplugged CPUs coming online do an enqueue but are not a part of any
root domain containing cpu_active() CPUs. So in this case, don't mess
with accounting and we can retry later. Without this patch, we see
crashes with sched_ext selftest's hotplug test due to divide by zero.
Signed-off-by: Joel Fernandes <joelagnelf@xxxxxxxxxx>
---
kernel/sched/deadline.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 3c478a1b2890d..753e50b1e86fc 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1689,7 +1689,12 @@ int dl_server_apply_params(struct sched_dl_entity *dl_se, u64 runtime, u64 perio
cpus = dl_bw_cpus(cpu);
cap = dl_bw_capacity(cpu);
- if (__dl_overflow(dl_b, cap, old_bw, new_bw))
+ /*
+ * Hotplugged CPUs coming online do an enqueue but are not a part of any
+ * root domain containing cpu_active() CPUs. So in this case, don't mess
+ * with accounting and we can retry later.
+ */
+ if (!cpus || __dl_overflow(dl_b, cap, old_bw, new_bw))
return -EBUSY;
if (init) {
--
2.51.0
