Re: [PATCH 1/4] mm: Move demotion related functions in memory-tiers.c

[Alexandre Ghiti]

Hi David,

On 3/12/26 13:56, David Hildenbrand (Arm) wrote:
> On 3/11/26 12:02, Alexandre Ghiti wrote:
> > Let's have all the demotion functions in this file, no functional
> > change intended.
> >
> > Suggested-by: Gregory Price <gourry@xxxxxxxxxx>
> > Signed-off-by: Alexandre Ghiti <alex@xxxxxxxx>
> > ---
> >   include/linux/memory-tiers.h | 18 ++++++++
> >   mm/memory-tiers.c            | 75 +++++++++++++++++++++++++++++++++
> >   mm/vmscan.c                  | 80 +-----------------------------------
> >   3 files changed, 94 insertions(+), 79 deletions(-)
> >
> > diff --git a/include/linux/memory-tiers.h b/include/linux/memory-tiers.h
> > index 96987d9d95a8..0bf0d002939e 100644
> > --- a/include/linux/memory-tiers.h
> > +++ b/include/linux/memory-tiers.h
> > @@ -56,6 +56,9 @@ void mt_put_memory_types(struct list_head *memory_types);
> >   int next_demotion_node(int node, const nodemask_t *allowed_mask);
> >   void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets);
> >   bool node_is_toptier(int node);
> > +unsigned int mt_demote_folios(struct list_head *demote_folios,
> > +			      struct pglist_data *pgdat,
> > +			      struct mem_cgroup *memcg);
> >   #else
> >   static inline int next_demotion_node(int node, const nodemask_t *allowed_mask)
> >   {
> > @@ -71,6 +74,14 @@ static inline bool node_is_toptier(int node)
> >   {
> >   	return true;
> >   }
> > +
> > +static inline unsigned int mt_demote_folios(struct list_head *demote_folios,
> > +					    struct pglist_data *pgdat,
> > +					    struct mem_cgroup *memcg)
> use two-tab indentation on second parameter line please. So this fits
> into a single line. Same for the other functions.
>
> Just like alloc_demote_folio() that you are moving already did.


Will do.


> [...]
>
> > -static struct folio *alloc_demote_folio(struct folio *src,
> > -		unsigned long private)
> > -{
> > -	struct folio *dst;
> > -	nodemask_t *allowed_mask;
> > -	struct migration_target_control *mtc;
> > -
> > -	mtc = (struct migration_target_control *)private;
> > -
> > -	allowed_mask = mtc->nmask;
> > -	/*
> > -	 * make sure we allocate from the target node first also trying to
> > -	 * demote or reclaim pages from the target node via kswapd if we are
> > -	 * low on free memory on target node. If we don't do this and if
> > -	 * we have free memory on the slower(lower) memtier, we would start
> > -	 * allocating pages from slower(lower) memory tiers without even forcing
> > -	 * a demotion of cold pages from the target memtier. This can result
> > -	 * in the kernel placing hot pages in slower(lower) memory tiers.
> > -	 */
> > -	mtc->nmask = NULL;
> > -	mtc->gfp_mask |= __GFP_THISNODE;
> > -	dst = alloc_migration_target(src, (unsigned long)mtc);
> > -	if (dst)
> > -		return dst;
> > -
> > -	mtc->gfp_mask &= ~__GFP_THISNODE;
> > -	mtc->nmask = allowed_mask;
> > -
> I think this function changed in the meantime in mm/mm-unstable. Against
> which branch is this patch?


Against Linus v7.0-rc3. I have just checked and you're right, I missed 
this modification, I'll rebase against mm-unstable.

Thanks,

Alex

>