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SubjectRe: [patch 10/11] mm: make per-memcg LRU lists exclusive
On Mon 12-09-11 12:57:27, Johannes Weiner wrote:
> Now that all code that operated on global per-zone LRU lists is
> converted to operate on per-memory cgroup LRU lists instead, there is
> no reason to keep the double-LRU scheme around any longer.
>
> The pc->lru member is removed and page->lru is linked directly to the
> per-memory cgroup LRU lists, which removes two pointers from a
> descriptor that exists for every page frame in the system.
>
> Signed-off-by: Johannes Weiner <jweiner@redhat.com>
> Signed-off-by: Hugh Dickins <hughd@google.com>
> Signed-off-by: Ying Han <yinghan@google.com>

Reviewed-by: Michal Hocko <mhocko@suse.cz>

Minor comments/questions bellow.
> ---
> include/linux/memcontrol.h | 54 +++-----
> include/linux/mm_inline.h | 21 +--
> include/linux/page_cgroup.h | 1 -
> mm/memcontrol.c | 319 ++++++++++++++++++++-----------------------
> mm/page_cgroup.c | 1 -
> mm/swap.c | 23 ++-
> mm/vmscan.c | 81 +++++-------
> 7 files changed, 228 insertions(+), 272 deletions(-)
>
[...]
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 465001c..a7d14a5 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
[...]
> @@ -934,115 +954,123 @@ EXPORT_SYMBOL(mem_cgroup_count_vm_event);
> * When moving account, the page is not on LRU. It's isolated.
> */
>
> -struct page *mem_cgroup_lru_to_page(struct zone *zone, struct mem_cgroup *mem,
> - enum lru_list lru)
> +/**
> + * mem_cgroup_lru_add_list - account for adding an lru page and return lruvec
> + * @zone: zone of the page
> + * @page: the page
> + * @lru: current lru
> + *
> + * This function accounts for @page being added to @lru, and returns
> + * the lruvec for the given @zone and the memcg @page is charged to.
> + *
> + * The callsite is then responsible for physically linking the page to
> + * the returned lruvec->lists[@lru].
> + */
> +struct lruvec *mem_cgroup_lru_add_list(struct zone *zone, struct page *page,
> + enum lru_list lru)

I know that names are alway tricky but what about mem_cgroup_acct_lru_add?
Analogously for mem_cgroup_lru_del_list, mem_cgroup_lru_del and
mem_cgroup_lru_move_lists.

[...]
> @@ -3615,11 +3593,11 @@ unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
> static int mem_cgroup_force_empty_list(struct mem_cgroup *memcg,
> int node, int zid, enum lru_list lru)
> {
> - struct zone *zone;
> struct mem_cgroup_per_zone *mz;
> - struct page_cgroup *pc, *busy;
> unsigned long flags, loop;
> struct list_head *list;
> + struct page *busy;
> + struct zone *zone;

Any specific reason to move zone declaration down here? Not that it
matters much. Just curious.

> int ret = 0;
>
> zone = &NODE_DATA(node)->node_zones[zid];
> @@ -3639,16 +3618,16 @@ static int mem_cgroup_force_empty_list(struct mem_cgroup *memcg,
> spin_unlock_irqrestore(&zone->lru_lock, flags);
> break;
> }
> - pc = list_entry(list->prev, struct page_cgroup, lru);
> - if (busy == pc) {
> - list_move(&pc->lru, list);
> + page = list_entry(list->prev, struct page, lru);
> + if (busy == page) {
> + list_move(&page->lru, list);
> busy = NULL;
> spin_unlock_irqrestore(&zone->lru_lock, flags);
> continue;
> }
> spin_unlock_irqrestore(&zone->lru_lock, flags);
>
> - page = lookup_cgroup_page(pc);
> + pc = lookup_page_cgroup(page);

lookup_page_cgroup might return NULL so we probably want BUG_ON(!pc)
here. We are not very consistent about checking the return value,
though.

--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic


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