On Sat 09-06-12 14:30:00, Aneesh Kumar K.V wrote:
> From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
>
> With HugeTLB pages, hugetlb cgroup is uncharged in compound page
> destructor. Since we are holding a hugepage reference,
Who is holding that reference? I do not see anybody calling get_page in
this patch...
> we can be sure that old page won't get uncharged till the last
> put_page().
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
> ---
> include/linux/hugetlb_cgroup.h | 8 ++++++++
> mm/hugetlb_cgroup.c | 21 +++++++++++++++++++++
> mm/migrate.c | 5 +++++
> 3 files changed, 34 insertions(+)
>
> diff --git a/include/linux/hugetlb_cgroup.h b/include/linux/hugetlb_cgroup.h
> index ba4836f..b64d067 100644
> --- a/include/linux/hugetlb_cgroup.h
> +++ b/include/linux/hugetlb_cgroup.h
> @@ -63,6 +63,8 @@ extern void hugetlb_cgroup_uncharge_page(int idx, unsigned long nr_pages,
> extern void hugetlb_cgroup_uncharge_cgroup(int idx, unsigned long nr_pages,
> struct hugetlb_cgroup *h_cg);
> extern int hugetlb_cgroup_file_init(int idx) __init;
> +extern void hugetlb_cgroup_migrate(struct page *oldhpage,
> + struct page *newhpage);
> #else
> static inline struct hugetlb_cgroup *hugetlb_cgroup_from_page(struct page *page)
> {
> @@ -112,5 +114,11 @@ static inline int __init hugetlb_cgroup_file_init(int idx)
> {
> return 0;
> }
> +
> +static inline void hugetlb_cgroup_migrate(struct page *oldhpage,
> + struct page *newhpage)
> +{
> + return;
> +}
> #endif /* CONFIG_MEM_RES_CTLR_HUGETLB */
> #endif
> diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
> index c2b7b8e..2d384fe 100644
> --- a/mm/hugetlb_cgroup.c
> +++ b/mm/hugetlb_cgroup.c
> @@ -394,6 +394,27 @@ int __init hugetlb_cgroup_file_init(int idx)
> return 0;
> }
>
> +void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage)
> +{
> + struct hugetlb_cgroup *h_cg;
> +
> + VM_BUG_ON(!PageHuge(oldhpage));
> +
> + if (hugetlb_cgroup_disabled())
> + return;
> +
> + spin_lock(&hugetlb_lock);
> + h_cg = hugetlb_cgroup_from_page(oldhpage);
> + set_hugetlb_cgroup(oldhpage, NULL);
> + cgroup_exclude_rmdir(&h_cg->css);
> +
> + /* move the h_cg details to new cgroup */
> + set_hugetlb_cgroup(newhpage, h_cg);
> + spin_unlock(&hugetlb_lock);
> + cgroup_release_and_wakeup_rmdir(&h_cg->css);
> + return;
> +}
> +
> struct cgroup_subsys hugetlb_subsys = {
> .name = "hugetlb",
> .create = hugetlb_cgroup_create,
> diff --git a/mm/migrate.c b/mm/migrate.c
> index fdce3a2..6c37c51 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -33,6 +33,7 @@
> #include <linux/memcontrol.h>
> #include <linux/syscalls.h>
> #include <linux/hugetlb.h>
> +#include <linux/hugetlb_cgroup.h>
> #include <linux/gfp.h>
>
> #include <asm/tlbflush.h>
> @@ -931,6 +932,10 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
>
> if (anon_vma)
> put_anon_vma(anon_vma);
> +
> + if (!rc)
> + hugetlb_cgroup_migrate(hpage, new_hpage);
> +
> unlock_page(hpage);
> out:
> put_page(new_hpage);
> --
> 1.7.10
>
--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic
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