2024-01-10 11:52:29

by Valentin Schneider

Subject: [PATCH] sched/isolation: Warn about missing isolcpus mask

Since an empty string is a valid cpulist, this cmdline option does not
trigger any warnings:

isolcpus=domain,

housekeeping_setup() just carries on and we end up with the housekeeping
mask being all CPUs in the system.

Check that there *is* a cpulist and that it isn't empty.

Signed-off-by: Valentin Schneider <[email protected]>
---
kernel/sched/isolation.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 373d42c707bc5..aa20cd1702199 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -120,7 +120,8 @@ static int __init housekeeping_setup(char *str, unsigned long flags)
}

alloc_bootmem_cpumask_var(&non_housekeeping_mask);
- if (cpulist_parse(str, non_housekeeping_mask) < 0) {
+ if (cpulist_parse(str, non_housekeeping_mask) < 0 ||
+ cpumask_empty(non_housekeeping_mask)) {
pr_warn("Housekeeping: nohz_full= or isolcpus= incorrect CPU range\n");
goto free_non_housekeeping_mask;
}
--
2.43.0

2024-01-10 14:15:05

by Frederic Weisbecker

Subject: Re: [PATCH] sched/isolation: Warn about missing isolcpus mask

Le Wed, Jan 10, 2024 at 12:46:10PM +0100, Valentin Schneider a ?crit :
> Since an empty string is a valid cpulist, this cmdline option does not
> trigger any warnings:
>
> isolcpus=domain,
>
> housekeeping_setup() just carries on and we end up with the housekeeping
> mask being all CPUs in the system.
>
> Check that there *is* a cpulist and that it isn't empty.
>
> Signed-off-by: Valentin Schneider <[email protected]>

Acked-by: Frederic Weisbecker <[email protected]>