Re: [PATCH v2 net] ipvs: Fix estimator kthreads preferred affinity

[Julian Anastasov <ja@xxxxxx>]

        Hello,

On Tue, 29 Jul 2025, Frederic Weisbecker wrote:

> The estimator kthreads' affinity are defined by sysctl overwritten
> preferences and applied through a plain call to the scheduler's affinity
> API.
> 
> However since the introduction of managed kthreads preferred affinity,
> such a practice shortcuts the kthreads core code which eventually
> overwrites the target to the default unbound affinity.
> 
> Fix this with using the appropriate kthread's API.
> 
> Fixes: d1a89197589c ("kthread: Default affine kthread to its preferred NUMA 
> node")
> Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx>

        Looks good to me for the nf tree, thanks!

Acked-by: Julian Anastasov <ja@xxxxxx>

> ---
>  include/net/ip_vs.h            | 13 +++++++++++++
>  kernel/kthread.c               |  1 +
>  net/netfilter/ipvs/ip_vs_est.c |  3 ++-
>  3 files changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
> index ff406ef4fd4a..29a36709e7f3 100644
> --- a/include/net/ip_vs.h
> +++ b/include/net/ip_vs.h
> @@ -1163,6 +1163,14 @@ static inline const struct cpumask 
> *sysctl_est_cpulist(struct netns_ipvs *ipvs)
>               return housekeeping_cpumask(HK_TYPE_KTHREAD);
>  }
>  
> +static inline const struct cpumask *sysctl_est_preferred_cpulist(struct 
> netns_ipvs *ipvs)
> +{
> +     if (ipvs->est_cpulist_valid)
> +             return ipvs->sysctl_est_cpulist;
> +     else
> +             return NULL;
> +}
> +
>  static inline int sysctl_est_nice(struct netns_ipvs *ipvs)
>  {
>       return ipvs->sysctl_est_nice;
> @@ -1270,6 +1278,11 @@ static inline const struct cpumask 
> *sysctl_est_cpulist(struct netns_ipvs *ipvs)
>       return housekeeping_cpumask(HK_TYPE_KTHREAD);
>  }
>  
> +static inline const struct cpumask *sysctl_est_preferred_cpulist(struct 
> netns_ipvs *ipvs)
> +{
> +     return NULL;
> +}
> +
>  static inline int sysctl_est_nice(struct netns_ipvs *ipvs)
>  {
>       return IPVS_EST_NICE;
> diff --git a/kernel/kthread.c b/kernel/kthread.c
> index 85e29b250107..adf06196b844 100644
> --- a/kernel/kthread.c
> +++ b/kernel/kthread.c
> @@ -899,6 +899,7 @@ int kthread_affine_preferred(struct task_struct *p, const 
> struct cpumask *mask)
>  
>       return ret;
>  }
> +EXPORT_SYMBOL_GPL(kthread_affine_preferred);
>  
>  static int kthreads_update_affinity(bool force)
>  {
> diff --git a/net/netfilter/ipvs/ip_vs_est.c b/net/netfilter/ipvs/ip_vs_est.c
> index f821ad2e19b3..15049b826732 100644
> --- a/net/netfilter/ipvs/ip_vs_est.c
> +++ b/net/netfilter/ipvs/ip_vs_est.c
> @@ -265,7 +265,8 @@ int ip_vs_est_kthread_start(struct netns_ipvs *ipvs,
>       }
>  
>       set_user_nice(kd->task, sysctl_est_nice(ipvs));
> -     set_cpus_allowed_ptr(kd->task, sysctl_est_cpulist(ipvs));
> +     if (sysctl_est_preferred_cpulist(ipvs))
> +             kthread_affine_preferred(kd->task, 
> sysctl_est_preferred_cpulist(ipvs));
>  
>       pr_info("starting estimator thread %d...\n", kd->id);
>       wake_up_process(kd->task);
> -- 
> 2.48.1

Regards

--
Julian Anastasov <ja@xxxxxx>