Re: [PATCH v2 1/1] mm: reduce NODE_RECLAIM_xxx and change to enum

[Petr Tesarik <ptesarik@suse.com>]

On Fri, 12 Jun 2026 16:57:08 +0200
"David Hildenbrand (Arm)" <david@kernel.org> wrote:

> On 6/12/26 10:50, Petr Tesarik wrote:
> > Change node_reclaim() to return an enum indicating whether any
> > pages have been reclaimed, because that's all the information
> > needed by the only caller, get_page_from_freelist().
> > 
> > This leads to the following translation of the old macro
> > identifiers to the new enum values:
> > 
> > - NODE_RECLAIM_NOSCAN  -> NODE_RECLAIM_NONE
> > - NODE_RECLAIM_FULL    -> NODE_RECLAIM_NONE
> > - NODE_RECLAIM_SOME    -> NODE_RECLAIM_SUCCESS
> > - NODE_RECLAIM_SUCCESS -> NODE_RECLAIM_SUCCESS  
> 
> Why not simply return the number of reclaimed pages (0 vs > 0)? I agree that a
> bool is not good.
> 
> Or if that is not good enough (for some reason) return 0 (success) vs. -ENOENT?

I don't have a strong opinion, except I hate the current code. ;-)

If we can agree that get_page_from_freelist() need not recheck with
zone_watermark_ok() after __node_reclaim() returns zero, then I believe
the cleanest option is to return the number of pages (zero if reclaim
was not even attempted).

Petr T