Re: [PATCH] Revert "genirq/affinity: assign vectors to all possible CPUs"

[Ming Lei <ming.lei@redhat.com>]

On Mon, Oct 01, 2018 at 02:33:07PM +0200, Paul Menzel wrote:
> Date: Wed, 29 Aug 2018 17:28:45 +0200
> 
> This reverts commit ef86f3a72adb8a7931f67335560740a7ad696d1d.
> 
> See the discussion in the thread *aacraid: Regression in 4.14.56
> with *genirq/affinity: assign vectors to all possible CPUs** on
> the linux-scsi list.
> 
> Reverting the commit, the aacraid driver loads correctly, and the
> drives are visible. So revert the commit to adhere to Linux’ no
> regression policy.
> 
> Strangely, the issue is not reproducible with Linux 4.18.x, but
> Ming Lei wrote, that this might only be by chance.
> 
> Link: https://www.spinics.net/lists/linux-scsi/msg122732.html
> Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
> 
> ---
>  kernel/irq/affinity.c | 30 +++++++++++++++---------------
>  1 file changed, 15 insertions(+), 15 deletions(-)
> 
> diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
> index a37a3b4b6342..e12d35108225 100644
> --- a/kernel/irq/affinity.c
> +++ b/kernel/irq/affinity.c
> @@ -39,7 +39,7 @@ static void irq_spread_init_one(struct cpumask *irqmsk, struct cpumask *nmsk,
>  	}
>  }
>  
> -static cpumask_var_t *alloc_node_to_possible_cpumask(void)
> +static cpumask_var_t *alloc_node_to_present_cpumask(void)
>  {
>  	cpumask_var_t *masks;
>  	int node;
> @@ -62,7 +62,7 @@ static cpumask_var_t *alloc_node_to_possible_cpumask(void)
>  	return NULL;
>  }
>  
> -static void free_node_to_possible_cpumask(cpumask_var_t *masks)
> +static void free_node_to_present_cpumask(cpumask_var_t *masks)
>  {
>  	int node;
>  
> @@ -71,22 +71,22 @@ static void free_node_to_possible_cpumask(cpumask_var_t *masks)
>  	kfree(masks);
>  }
>  
> -static void build_node_to_possible_cpumask(cpumask_var_t *masks)
> +static void build_node_to_present_cpumask(cpumask_var_t *masks)
>  {
>  	int cpu;
>  
> -	for_each_possible_cpu(cpu)
> +	for_each_present_cpu(cpu)
>  		cpumask_set_cpu(cpu, masks[cpu_to_node(cpu)]);
>  }
>  
> -static int get_nodes_in_cpumask(cpumask_var_t *node_to_possible_cpumask,
> +static int get_nodes_in_cpumask(cpumask_var_t *node_to_present_cpumask,
>  				const struct cpumask *mask, nodemask_t *nodemsk)
>  {
>  	int n, nodes = 0;
>  
>  	/* Calculate the number of nodes in the supplied affinity mask */
>  	for_each_node(n) {
> -		if (cpumask_intersects(mask, node_to_possible_cpumask[n])) {
> +		if (cpumask_intersects(mask, node_to_present_cpumask[n])) {
>  			node_set(n, *nodemsk);
>  			nodes++;
>  		}
> @@ -109,7 +109,7 @@ irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
>  	int last_affv = affv + affd->pre_vectors;
>  	nodemask_t nodemsk = NODE_MASK_NONE;
>  	struct cpumask *masks;
> -	cpumask_var_t nmsk, *node_to_possible_cpumask;
> +	cpumask_var_t nmsk, *node_to_present_cpumask;
>  
>  	/*
>  	 * If there aren't any vectors left after applying the pre/post
> @@ -125,8 +125,8 @@ irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
>  	if (!masks)
>  		goto out;
>  
> -	node_to_possible_cpumask = alloc_node_to_possible_cpumask();
> -	if (!node_to_possible_cpumask)
> +	node_to_present_cpumask = alloc_node_to_present_cpumask();
> +	if (!node_to_present_cpumask)
>  		goto out;
>  
>  	/* Fill out vectors at the beginning that don't need affinity */
> @@ -135,8 +135,8 @@ irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
>  
>  	/* Stabilize the cpumasks */
>  	get_online_cpus();
> -	build_node_to_possible_cpumask(node_to_possible_cpumask);
> -	nodes = get_nodes_in_cpumask(node_to_possible_cpumask, cpu_possible_mask,
> +	build_node_to_present_cpumask(node_to_present_cpumask);
> +	nodes = get_nodes_in_cpumask(node_to_present_cpumask, cpu_present_mask,
>  				     &nodemsk);
>  
>  	/*
> @@ -146,7 +146,7 @@ irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
>  	if (affv <= nodes) {
>  		for_each_node_mask(n, nodemsk) {
>  			cpumask_copy(masks + curvec,
> -				     node_to_possible_cpumask[n]);
> +				     node_to_present_cpumask[n]);
>  			if (++curvec == last_affv)
>  				break;
>  		}
> @@ -160,7 +160,7 @@ irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
>  		vecs_per_node = (affv - (curvec - affd->pre_vectors)) / nodes;
>  
>  		/* Get the cpus on this node which are in the mask */
> -		cpumask_and(nmsk, cpu_possible_mask, node_to_possible_cpumask[n]);
> +		cpumask_and(nmsk, cpu_present_mask, node_to_present_cpumask[n]);
>  
>  		/* Calculate the number of cpus per vector */
>  		ncpus = cpumask_weight(nmsk);
> @@ -192,7 +192,7 @@ irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
>  	/* Fill out vectors at the end that don't need affinity */
>  	for (; curvec < nvecs; curvec++)
>  		cpumask_copy(masks + curvec, irq_default_affinity);
> -	free_node_to_possible_cpumask(node_to_possible_cpumask);
> +	free_node_to_present_cpumask(node_to_present_cpumask);
>  out:
>  	free_cpumask_var(nmsk);
>  	return masks;
> @@ -214,7 +214,7 @@ int irq_calc_affinity_vectors(int minvec, int maxvec, const struct irq_affinity
>  		return 0;
>  
>  	get_online_cpus();
> -	ret = min_t(int, cpumask_weight(cpu_possible_mask), vecs) + resv;
> +	ret = min_t(int, cpumask_weight(cpu_present_mask), vecs) + resv;
>  	put_online_cpus();
>  	return ret;
>  }
> -- 
> 2.17.1
> 

Hello Paul,

I have explained that this is one aacraid issue in the following link:

https://marc.info/?l=linux-kernel&m=153413115909580&w=2

So this issue should have been fixed in the driver instead of genirq
core code, otherwise regression on other drivers can be caused too.

So I suggest you to ask aacraid guys to take a look at this issue.

Thanks,
Ming