On 13 Nov 2020, at 19:23, Roman Gushchin wrote:
> On Wed, Nov 11, 2020 at 03:40:04PM -0500, Zi Yan wrote:
>> From: Zi Yan <ziy@xxxxxxxxxx>
>>
>> It reads thp_nr_pages and splits to provided new_nr. It prepares for
>> upcoming changes to support split huge page to any lower order.
>>
>> Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
>> ---
>> include/linux/memcontrol.h | 5 +++--
>> mm/huge_memory.c | 2 +-
>> mm/memcontrol.c | 4 ++--
>> 3 files changed, 6 insertions(+), 5 deletions(-)
>>
>> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
>> index 0f4dd7829fb2..b3bac79ceed6 100644
>> --- a/include/linux/memcontrol.h
>> +++ b/include/linux/memcontrol.h
>> @@ -1105,7 +1105,7 @@ static inline void memcg_memory_event_mm(struct mm_struct *mm,
>> }
>>
>> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>> -void mem_cgroup_split_huge_fixup(struct page *head);
>> +void mem_cgroup_split_huge_fixup(struct page *head, unsigned int new_nr);
>> #endif
>>
>> #else /* CONFIG_MEMCG */
>> @@ -1451,7 +1451,8 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
>> return 0;
>> }
>>
>> -static inline void mem_cgroup_split_huge_fixup(struct page *head)
>> +static inline void mem_cgroup_split_huge_fixup(struct page *head,
>> + unsigned int new_nr)
>> {
>> }
>>
>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
>> index c4fead5ead31..f599f5b9bf7f 100644
>> --- a/mm/huge_memory.c
>> +++ b/mm/huge_memory.c
>> @@ -2429,7 +2429,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
>> lruvec = mem_cgroup_page_lruvec(head, pgdat);
>>
>> /* complete memcg works before add pages to LRU */
>> - mem_cgroup_split_huge_fixup(head);
>> + mem_cgroup_split_huge_fixup(head, 1);
>>
>> if (PageAnon(head) && PageSwapCache(head)) {
>> swp_entry_t entry = { .val = page_private(head) };
>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>> index 33f632689cee..e9705ba6bbcc 100644
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
>> @@ -3247,7 +3247,7 @@ void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size)
>> * Because tail pages are not marked as "used", set it. We're under
>> * pgdat->lru_lock and migration entries setup in all page mappings.
>> */
>> -void mem_cgroup_split_huge_fixup(struct page *head)
>> +void mem_cgroup_split_huge_fixup(struct page *head, unsigned int new_nr)
>
> I'd go with unsigned int new_order, then it's obvious that we can split
> the original page without any leftovers.
Makes sense. Will change it.
>
> Other than that the patch looks good!
> Acked-by: Roman Gushchin <guro@xxxxxx>
Thanks.
>> {
>> struct mem_cgroup *memcg = page_memcg(head);
>> int i;
>> @@ -3255,7 +3255,7 @@ void mem_cgroup_split_huge_fixup(struct page *head)
>> if (mem_cgroup_disabled())
>> return;
>>
>> - for (i = 1; i < thp_nr_pages(head); i++) {
>> + for (i = new_nr; i < thp_nr_pages(head); i += new_nr) {
>> css_get(&memcg->css);
>> head[i].memcg_data = (unsigned long)memcg;
>> }
>> --
>> 2.28.0
>>
—
Best Regards,
Yan Zi
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