linux-kernel - Re: [PATCH v2] irq: consider cpus on nodes are unbalanced

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Date:   Fri, 17 Dec 2021 20:04:30 +0800
From:   Ming Lei <ming.lei@...hat.com>
To:     Rei Yamamoto <yamamoto.rei@...fujitsu.com>
Cc:     tglx@...utronix.de, hch@....de, kbusch@...nel.org,
        linux-kernel@...r.kernel.org, maz@...nel.org
Subject: Re: [PATCH v2] irq: consider cpus on nodes are unbalanced

On Fri, Dec 17, 2021 at 07:44:07PM +0900, Rei Yamamoto wrote:
> If cpus on a node are offline at boot time, there are
> difference in the number of nodes between when building affinity
> masks for present cpus and when building affinity masks for possible
> cpus. This patch fixes a problem caused by the difference of the
> number of nodes:
> 
>  - The routine of "numvecs <= nodes" condition can overwrite bits of
>    masks for present cpus in building masks for possible cpus. Fix this
>    problem by making CPU bits, which is not target, not changing.
> 
> Signed-off-by: Rei Yamamoto <yamamoto.rei@...fujitsu.com>
> ---
>  kernel/irq/affinity.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
> index f7ff8919dc9b..d2d01565d2ec 100644
> --- a/kernel/irq/affinity.c
> +++ b/kernel/irq/affinity.c
> @@ -269,8 +269,9 @@ static int __irq_build_affinity_masks(unsigned int startvec,
>  	 */
>  	if (numvecs <= nodes) {
>  		for_each_node_mask(n, nodemsk) {
> +			cpumask_and(nmsk, cpu_mask, node_to_cpumask[n]);
>  			cpumask_or(&masks[curvec].mask, &masks[curvec].mask,
> -				   node_to_cpumask[n]);
> +				   nmsk);
>  			if (++curvec == last_affv)
>  				curvec = firstvec;

Looks fine,

Reviewed-by: Ming Lei <ming.lei@...hat.com>

-- 
Ming