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

Alexandre Ghiti
2026-03-13T13:45:21Z

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@gourry.net>
>> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
>> ---
>> 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

>