The patch titled
Subject: mm: remove references to folio in split_page_memcg()
has been added to the -mm mm-unstable branch. Its filename is
mm-remove-references-to-folio-in-split_page_memcg.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-remove-references-to-folio-in-split_page_memcg.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: mm: remove references to folio in split_page_memcg()
Date: Fri, 14 Mar 2025 13:36:13 +0000
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@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: Shakeel Butt <shakeel.butt@xxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 30 +++++++++++++++++++++++-------
1 file changed, 23 insertions(+), 7 deletions(-)
--- a/mm/memcontrol.c~mm-remove-references-to-folio-in-split_page_memcg
+++ a/mm/memcontrol.c
@@ -2677,6 +2677,23 @@ out:
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
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_
* 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,
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
mm-decline-to-manipulate-the-refcount-on-a-slab-page.patch
dax-remove-access-to-page-index.patch
dax-use-folios-more-widely-within-dax.patch
fs-convert-block_commit_write-to-take-a-folio.patch
fs-remove-page_file_mapping.patch
fs-remove-folio_file_mapping.patch
mm-assert-the-folio-is-locked-in-folio_start_writeback.patch
hugetlb-convert-hugetlb_vma_maps_page-to-hugetlb_vma_maps_pfn.patch
hugetlb-convert-adjust_range_hwpoison-to-take-a-folio.patch
mm-convert-lru_add_page_tail-to-lru_add_split_folio.patch
mm-separate-folio_split_memcg_refs-from-split_page_memcg.patch
mm-simplify-split_page_memcg.patch
mm-remove-references-to-folio-in-split_page_memcg.patch
mm-simplify-folio_memcg_charged.patch
mm-remove-references-to-folio-in-__memcg_kmem_uncharge_page.patch
ocfs2-use-memcpy_to_folio-in-ocfs2_symlink_get_block.patch
ocfs2-remove-reference-to-bh-b_page.patch
