On Tue 13-04-21 14:51:50, Muchun Song wrote:
> We already have a helper lruvec_memcg() to get the memcg from lruvec, we
> do not need to do it ourselves in the lruvec_holds_page_lru_lock(). So use
> lruvec_memcg() instead. And if mem_cgroup_disabled() returns false, the
> page_memcg(page) (the LRU pages) cannot be NULL. So remove the odd logic
> of "memcg = page_memcg(page) ? : root_mem_cgroup". And use lruvec_pgdat
> to simplify the code. We can have a single definition for this function
> that works for !CONFIG_MEMCG, CONFIG_MEMCG + mem_cgroup_disabled() and
> CONFIG_MEMCG.
Neat. While you are at it wouldn't it make sesne to rename the function
as well. I do not want to bikeshed but this is really a misnomer. it
doesn't check anything about locking. page_belongs_lruvec?
> Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
> include/linux/memcontrol.h | 31 +++++++------------------------
> 1 file changed, 7 insertions(+), 24 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 4f49865c9958..38b8d3fb24ff 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -755,22 +755,6 @@ static inline struct lruvec *mem_cgroup_page_lruvec(struct page *page)
> return mem_cgroup_lruvec(memcg, pgdat);
> }
>
> -static inline bool lruvec_holds_page_lru_lock(struct page *page,
> - struct lruvec *lruvec)
> -{
> - pg_data_t *pgdat = page_pgdat(page);
> - const struct mem_cgroup *memcg;
> - struct mem_cgroup_per_node *mz;
> -
> - if (mem_cgroup_disabled())
> - return lruvec == &pgdat->__lruvec;
> -
> - mz = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
> - memcg = page_memcg(page) ? : root_mem_cgroup;
> -
> - return lruvec->pgdat == pgdat && mz->memcg == memcg;
> -}
> -
> struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);
>
> struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm);
> @@ -1229,14 +1213,6 @@ static inline struct lruvec *mem_cgroup_page_lruvec(struct page *page)
> return &pgdat->__lruvec;
> }
>
> -static inline bool lruvec_holds_page_lru_lock(struct page *page,
> - struct lruvec *lruvec)
> -{
> - pg_data_t *pgdat = page_pgdat(page);
> -
> - return lruvec == &pgdat->__lruvec;
> -}
> -
> static inline void lruvec_memcg_debug(struct lruvec *lruvec, struct page *page)
> {
> }
> @@ -1518,6 +1494,13 @@ static inline void unlock_page_lruvec_irqrestore(struct lruvec *lruvec,
> spin_unlock_irqrestore(&lruvec->lru_lock, flags);
> }
>
> +static inline bool lruvec_holds_page_lru_lock(struct page *page,
> + struct lruvec *lruvec)
> +{
> + return lruvec_pgdat(lruvec) == page_pgdat(page) &&
> + lruvec_memcg(lruvec) == page_memcg(page);
> +}
> +
> /* Don't lock again iff page's lruvec locked */
> static inline struct lruvec *relock_page_lruvec_irq(struct page *page,
> struct lruvec *locked_lruvec)
> --
> 2.11.0
--
Michal Hocko
SUSE Labs
