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| author |   Zhou Guanghui <zhouguanghui1@huawei.com> | 2021-03-12 21:08:33 -0800 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2021-03-13 11:27:31 -0800 |
| commit | e1baddf8475b06cc56f4bafecf9a32a124343d9f (patch) | |
| tree | 234f0f728ac7575508962af8a8f8b2dbeae2576a /mm | |
| parent | mm/memcg: rename mem_cgroup_split_huge_fixup to split_page_memcg and add nr_pages argument (diff) | |
| download | linux-dev-e1baddf8475b06cc56f4bafecf9a32a124343d9f.tar.xz linux-dev-e1baddf8475b06cc56f4bafecf9a32a124343d9f.zip | |
mm/memcg: set memcg when splitting page
As described in the split_page() 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 splitting a
page.
Michel:
There are at least two explicit users of __GFP_ACCOUNT with
alloc_exact_pages added recently. See 7efe8ef274024 ("KVM: arm64:
Allocate stage-2 pgd pages with GFP_KERNEL_ACCOUNT") and c419621873713
("KVM: s390: Add memcg accounting to KVM allocations"), so this is not
just a theoretical issue.
Link: https://lkml.kernel.org/r/20210304074053.65527-3-zhouguanghui1@huawei.com
Signed-off-by: Zhou Guanghui <zhouguanghui1@huawei.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Rui Xiang <rui.xiang@huawei.com>
Cc: Tianhong Ding <dingtianhong@huawei.com>
Cc: Weilong Chen <chenweilong@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/page_alloc.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 3cd1c0ce4d06..cfc72873961d 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3314,6 +3314,7 @@ void split_page(struct page *page, unsigned int order) 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); |