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

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Date:   Fri, 14 Jan 2022 10:58:30 +0900
From:   Rei Yamamoto <yamamoto.rei@...fujitsu.com>
To:     tglx@...utronix.de
Cc:     hch@....de, kbusch@...nel.org, linux-kernel@...r.kernel.org,
        maz@...nel.org, ming.lei@...hat.com, yamamoto.rei@...fujitsu.com
Subject: Re: [PATCH v2] irq: consider cpus on nodes are unbalanced

On Fri, Dec 17, 2021 at 20:04, Ming Lei wrote:
> 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>

Thank you for your review.
Does anyone else have a comment?

Thanks,
Rei