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

[Alexandre Ghiti <alex@ghiti.fr>]

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

>