Re: [PATCH] mm/swapfile.c: select the swap device with default priority round robin

[Baoquan He <bhe@redhat.com>]

On 09/25/25 at 01:34am, YoungJun Park wrote:
> On Wed, Sep 24, 2025 at 05:17:46PM +0800, Baoquan He wrote:
> > -	int i;
> > -
> > -	if (prio >= 0)
> > -		si->prio = prio;
> > -	else
> > -		si->prio = --least_priority;
> > +	si->prio = prio;
> 
> 
> > -     if (p->prio < 0) {
> > -             struct swap_info_struct *si = p;
> > -             int nid;
> > -
> > -             plist_for_each_entry_continue(si, &swap_active_head, list) {
> > -                     si->prio++;
> > -                     si->list.prio--;
> > -                     for_each_node(nid) {
> > -                             if (si->avail_lists[nid].prio != 1)
> > -                                     si->avail_lists[nid].prio--;
> > -                     }
> > -             }
> > -             least_priority++;
> > -     }
>  
> Hi Baoquan He,
> 
> I noticed that in `_enable_swap_info()` there is still a comment describing
> the behavior that this patch removes(auto assigning priority). 
> Shouldn’t that part also be updated accordingly?

You are right, this need be updated. Will change in v2. Thanks a lot for
careful reviewing.

> 
> static void _enable_swap_info(struct swap_info_struct *si)
> {
>         ...
>         /*
>          * both lists are plists, and thus priority ordered.
>          * swap_active_head needs to be priority ordered for swapoff(),
>          * which on removal of any swap_info_struct with an auto-assigned
>          * (i.e. negative) priority increments the auto-assigned priority
>          * of any lower-priority swap_info_structs.
>          * swap_avail_head needs to be priority ordered for folio_alloc_swap(),
>          * which allocates swap pages from the highest available priority
>          * swap_info_struct.
>          */
> 
> Best regards,
> Youngjun Park
>