Re: [PATCH 1/7] xen/mm: Normalize common per-domain page counters to unsigned long

[Jan Beulich <jbeulich@xxxxxxxx>]

On 29.05.2026 14:43, Bernhard Kaindl wrote:
> --- a/xen/include/xen/sched.h
> +++ b/xen/include/xen/sched.h
> @@ -414,17 +414,17 @@ struct domain
>       * This field should only be directly accessed by 
> domain_adjust_tot_pages()
>       * and the domain_tot_pages() helper function defined below.
>       */
> -    unsigned int     tot_pages;
> +    unsigned long    tot_pages;
>  
> -    unsigned int     xenheap_pages;     /* pages allocated from Xen heap */
> +    unsigned long    xenheap_pages;     /* pages allocated from Xen heap */

I'd like to at least raise the question: Are we perhaps going too far by
promoting this and ...

>      /* Pages claimed but not possessed, protected by global heap_lock. */
> -    unsigned int     outstanding_pages;
> -    unsigned int     node_claims;       /* Sum of per-node claims. */
> +    unsigned long    outstanding_pages;
> +    unsigned long    node_claims;       /* Sum of per-node claims. */
>      /* Domain objects use dedicated pages, leaving room for per-node claims. 
> */
> -    unsigned int     claims[MAX_NUMNODES]; /* Per-NUMA-node claims. */
> +    unsigned long    claims[MAX_NUMNODES]; /* Per-NUMA-node claims. */
>  
> -    unsigned int     max_pages;         /* maximum value for 
> domain_tot_pages() */
> -    unsigned int     extra_pages;       /* pages not included in 
> domain_tot_pages() */
> +    unsigned long    max_pages;         /* maximum value for 
> domain_tot_pages() */
> +    unsigned long    extra_pages;       /* pages not included in 
> domain_tot_pages() */

... this field as well?

For claims[] in particular the doubling of space needed also isn't entirely
nice, especially when people (distros) build with a large NR_NUMA_NODES (aka
MAX_NUMNODES) but the hypervisor then runs on a few-nodes or even non-NUMA
system.

Jan