Re: [PATCH 05/33] sched/isolation: Save boot defined domain flags

Waiman Long
2026-01-12T18:04:13Z

On 1/1/26 5:13 PM, Frederic Weisbecker wrote:
> HK_TYPE_DOMAIN will soon integrate not only boot defined isolcpus= CPUs
> but also cpuset isolated partitions.
>
> Housekeeping still needs a way to record what was initially passed
> to isolcpus= in order to keep these CPUs isolated after a cpuset
> isolated partition is modified or destroyed while containing some of
> them.
>
> Create a new HK_TYPE_DOMAIN_BOOT to keep track of those.
>
> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
> Reviewed-by: Phil Auld <pauld@redhat.com>
> ---
> include/linux/sched/isolation.h | 4 ++++
> kernel/sched/isolation.c | 5 +++--
> 2 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
> index d8501f4709b5..c7cf6934489c 100644
> --- a/include/linux/sched/isolation.h
> +++ b/include/linux/sched/isolation.h
> @@ -7,8 +7,12 @@
> #include <linux/tick.h>
>
> enum hk_type {
> + /* Inverse of boot-time isolcpus= argument */
> + HK_TYPE_DOMAIN_BOOT,
> HK_TYPE_DOMAIN,
> + /* Inverse of boot-time isolcpus=managed_irq argument */
> HK_TYPE_MANAGED_IRQ,
> + /* Inverse of boot-time nohz_full= or isolcpus=nohz arguments */
> HK_TYPE_KERNEL_NOISE,
> HK_TYPE_MAX,
>
> diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
> index 3ad0d6df6a0a..11a623fa6320 100644
> --- a/kernel/sched/isolation.c
> +++ b/kernel/sched/isolation.c
> @@ -11,6 +11,7 @@
> #include "sched.h"
>
> enum hk_flags {
> + HK_FLAG_DOMAIN_BOOT = BIT(HK_TYPE_DOMAIN_BOOT),
> HK_FLAG_DOMAIN = BIT(HK_TYPE_DOMAIN),
> HK_FLAG_MANAGED_IRQ = BIT(HK_TYPE_MANAGED_IRQ),
> HK_FLAG_KERNEL_NOISE = BIT(HK_TYPE_KERNEL_NOISE),
> @@ -239,7 +240,7 @@ static int __init housekeeping_isolcpus_setup(char *str)
>
> if (!strncmp(str, "domain,", 7)) {
> str += 7;
> - flags |= HK_FLAG_DOMAIN;
> + flags |= HK_FLAG_DOMAIN | HK_FLAG_DOMAIN_BOOT;
> continue;
> }
>
> @@ -269,7 +270,7 @@ static int __init housekeeping_isolcpus_setup(char *str)
>
> /* Default behaviour for isolcpus without flags */
> if (!flags)
> - flags |= HK_FLAG_DOMAIN;
> + flags |= HK_FLAG_DOMAIN | HK_FLAG_DOMAIN_BOOT;
>
> return housekeeping_setup(str, flags);
> }
Reviewed-by: Waiman Long <longman@redhat.com>