Re: [PATCH] mm/hugetlb_cgroup: Add list_del to remove unused page from hugepage_activelist when hugepage migration

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

Wanpeng Li <liwp.linux@gmail.com> writes:

> From: Wanpeng Li <liwp@linux.vnet.ibm.com>
>
> hugepage_activelist is used to track currently used HugeTLB pages.
> We can find the in-use HugeTLB pages to support HugeTLB cgroup
> removal. Don't keep unused page in hugetlb_activelist too long.
> Otherwise, on cgroup removal we should update the unused page's 
> charge to parent count. To reduce this overhead, remove unused page 
> from hugepage_activelist immediately.
>
> Signed-off-by: Wanpeng Li <liwp.linux@gmail.com>
> ---
>  mm/hugetlb_cgroup.c |    1 +
>  1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
> index b834e8d..d819d66 100644
> --- a/mm/hugetlb_cgroup.c
> +++ b/mm/hugetlb_cgroup.c
> @@ -398,6 +398,7 @@ void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage)
>  	spin_lock(&hugetlb_lock);
>  	h_cg = hugetlb_cgroup_from_page(oldhpage);
>  	set_hugetlb_cgroup(oldhpage, NULL);
> +	list_del(&oldhpage->lru);
>
>  	/* move the h_cg details to new cgroup */
>  	set_hugetlb_cgroup(newhpage, h_cg);

put_page on the oldhpage will do that. If we do list_del here
free_huge_page() will have error list_move().

-aneesh

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