On Wed, Jul 15, 2015 at 6:54 AM, Vladimir Davydov
<vdavydov@xxxxxxxxxxxxx> wrote:
> This function returns the inode number of the closest online ancestor of
> the memory cgroup a page is charged to. It is required for exporting
> information about which page is charged to which cgroup to userspace,
> which will be introduced by a following patch.
>
> Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Reviewed-by: Andres Lagar-Cavilla <andreslc@xxxxxxxxxx>
> ---
> include/linux/memcontrol.h | 1 +
> mm/memcontrol.c | 23 +++++++++++++++++++++++
> 2 files changed, 24 insertions(+)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 73b02b0a8f60..50069abebc3c 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -116,6 +116,7 @@ static inline bool mm_match_cgroup(struct mm_struct *mm,
>
> extern struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *memcg);
> extern struct cgroup_subsys_state *mem_cgroup_css_from_page(struct page *page);
> +extern unsigned long page_cgroup_ino(struct page *page);
>
> struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *,
> struct mem_cgroup *,
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index acb93c554f6e..894dc2169979 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -631,6 +631,29 @@ struct cgroup_subsys_state *mem_cgroup_css_from_page(struct page *page)
> return &memcg->css;
> }
>
> +/**
> + * page_cgroup_ino - return inode number of the memcg a page is charged to
> + * @page: the page
> + *
> + * Look up the closest online ancestor of the memory cgroup @page is charged to
> + * and return its inode number or 0 if @page is not charged to any cgroup. It
> + * is safe to call this function without holding a reference to @page.
> + */
> +unsigned long page_cgroup_ino(struct page *page)
> +{
> + struct mem_cgroup *memcg;
> + unsigned long ino = 0;
> +
> + rcu_read_lock();
> + memcg = READ_ONCE(page->mem_cgroup);
> + while (memcg && !(memcg->css.flags & CSS_ONLINE))
> + memcg = parent_mem_cgroup(memcg);
> + if (memcg)
> + ino = cgroup_ino(memcg->css.cgroup);
> + rcu_read_unlock();
> + return ino;
> +}
> +
> static struct mem_cgroup_per_zone *
> mem_cgroup_page_zoneinfo(struct mem_cgroup *memcg, struct page *page)
> {
> --
> 2.1.4
>
--
Andres Lagar-Cavilla | Google Kernel Team | andreslc@xxxxxxxxxx
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