The patch titled
Subject: mm/memcg: set memcg when split page
has been added to the -mm tree. Its filename is
mm-memcg-set-memcg-when-split-page.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-memcg-set-memcg-when-split-page.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-memcg-set-memcg-when-split-page.patch
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------------------------------------------------------
From: Zhou Guanghui <zhouguanghui1@xxxxxxxxxx>
Subject: mm/memcg: set memcg when split page
As described in the split_page function comment, for the non-compound high
order page, the sub-pages must be freed individually. If the memcg of the
first page is valid, the tail pages cannot be uncharged when be freed.
For example, when alloc_pages_exact is used to allocate 1MB continuous
physical memory, 2MB is charged(kmemcg is enabled and __GFP_ACCOUNT is
set). When make_alloc_exact free the unused 1MB and free_pages_exact free
the applied 1MB, actually, only 4KB(one page) is uncharged.
Therefore, the memcg of the tail page needs to be set when split page.
Link: https://lkml.kernel.org/r/20210304074053.65527-3-zhouguanghui1@xxxxxxxxxx
Signed-off-by: Zhou Guanghui <zhouguanghui1@xxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Hanjun Guo <guohanjun@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Rui Xiang <rui.xiang@xxxxxxxxxx>
Cc: Tianhong Ding <dingtianhong@xxxxxxxxxx>
Cc: Weilong Chen <chenweilong@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 1 +
1 file changed, 1 insertion(+)
--- a/mm/page_alloc.c~mm-memcg-set-memcg-when-split-page
+++ a/mm/page_alloc.c
@@ -3314,6 +3314,7 @@ void split_page(struct page *page, unsig
for (i = 1; i < (1 << order); i++)
set_page_refcounted(page + i);
split_page_owner(page, 1 << order);
+ split_page_memcg(page, 1 << order);
}
EXPORT_SYMBOL_GPL(split_page);
_
Patches currently in -mm which might be from zhouguanghui1@xxxxxxxxxx are
mm-memcg-rename-mem_cgroup_split_huge_fixup-to-split_page_memcg.patch
mm-memcg-set-memcg-when-split-page.patch
