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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 --- 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 4aefb34a1d38b..f2f5b1aea8e2b 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1665,7 +1665,12 @@ 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