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mm: remove references to folio in split_page_memcg()

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We know that the passed in page is not part of a folio (it's a plain page
allocated with GFP_ACCOUNT), so we should get rid of the misleading
references to folios.

Introduce page_objcg() and page_set_objcg() helpers to make things more
clear.

Link: https://lkml.kernel.org/r/20250314133617.138071-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2025-03-14 13:36:13 +00:00 committed by Andrew Morton
parent 1506c25508
commit 7cc57ecae4
1 changed files with 23 additions and 7 deletions
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30
mm/memcontrol.c
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@ -2677,6 +2677,23 @@ static int obj_cgroup_charge_pages(struct obj_cgroup *objcg, gfp_t gfp,
return ret;
}
static struct obj_cgroup *page_objcg(const struct page *page)
{
unsigned long memcg_data = page->memcg_data;
if (mem_cgroup_disabled() || !memcg_data)
return NULL;
VM_BUG_ON_PAGE((memcg_data & OBJEXTS_FLAGS_MASK) != MEMCG_DATA_KMEM,
page);
return (struct obj_cgroup *)(memcg_data - MEMCG_DATA_KMEM);
}
static void page_set_objcg(struct page *page, const struct obj_cgroup *objcg)
{
page->memcg_data = (unsigned long)objcg | MEMCG_DATA_KMEM;
}
/**
* __memcg_kmem_charge_page: charge a kmem page to the current memory cgroup
* @page: page to charge
@ -2695,8 +2712,7 @@ int __memcg_kmem_charge_page(struct page *page, gfp_t gfp, int order)
ret = obj_cgroup_charge_pages(objcg, gfp, 1 << order);
if (!ret) {
obj_cgroup_get(objcg);
page->memcg_data = (unsigned long)objcg |
MEMCG_DATA_KMEM;
page_set_objcg(page, objcg);
return 0;
}
}
@ -3069,18 +3085,18 @@ void __memcg_slab_free_hook(struct kmem_cache *s, struct slab *slab,
* The objcg is only set on the first page, so transfer it to all the
* other pages.
*/
void split_page_memcg(struct page *first, unsigned order)
void split_page_memcg(struct page *page, unsigned order)
{
struct folio *folio = page_folio(first);
struct obj_cgroup *objcg = page_objcg(page);
unsigned int i, nr = 1 << order;
if (mem_cgroup_disabled() || !folio_memcg_charged(folio))
if (!objcg)
return;
for (i = 1; i < nr; i++)
folio_page(folio, i)->memcg_data = folio->memcg_data;
page_set_objcg(&page[i], objcg);
obj_cgroup_get_many(__folio_objcg(folio), nr - 1);
obj_cgroup_get_many(objcg, nr - 1);
}
void folio_split_memcg_refs(struct folio *folio, unsigned old_order,