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Date: Fri, 9 Jan 2015 10:45:35 +0100 From: Michal Hocko <mhocko@...e.cz> To: Vladimir Davydov <vdavydov@...allels.com> Cc: Andrew Morton <akpm@...ux-foundation.org>, Johannes Weiner <hannes@...xchg.org>, Tejun Heo <tj@...nel.org>, linux-mm@...ck.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH v2] vmscan: force scan offline memory cgroups On Fri 09-01-15 11:09:43, Vladimir Davydov wrote: > Since commit b2052564e66d ("mm: memcontrol: continue cache reclaim from > offlined groups") pages charged to a memory cgroup are not reparented > when the cgroup is removed. Instead, they are supposed to be reclaimed > in a regular way, along with pages accounted to online memory cgroups. > > However, an lruvec of an offline memory cgroup will sooner or later get > so small that it will be scanned only at low scan priorities (see > get_scan_count()). Therefore, if there are enough reclaimable pages in > big lruvecs, pages accounted to offline memory cgroups will never be > scanned at all, wasting memory. > > Fix this by unconditionally forcing scanning dead lruvecs from kswapd. > > Signed-off-by: Vladimir Davydov <vdavydov@...allels.com> Acked-by: Michal Hocko <mhocko@...e.cz> Thanks! > --- > Changes in v2: > - code style fixes (Johannes) > > include/linux/memcontrol.h | 6 ++++++ > mm/memcontrol.c | 14 ++++++++++++++ > mm/vmscan.c | 8 ++++++-- > 3 files changed, 26 insertions(+), 2 deletions(-) > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index 76b4084b8d08..68f3b44ef27c 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -102,6 +102,7 @@ void mem_cgroup_iter_break(struct mem_cgroup *, struct mem_cgroup *); > * For memory reclaim. > */ > int mem_cgroup_inactive_anon_is_low(struct lruvec *lruvec); > +bool mem_cgroup_lruvec_online(struct lruvec *lruvec); > int mem_cgroup_select_victim_node(struct mem_cgroup *memcg); > unsigned long mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list); > void mem_cgroup_update_lru_size(struct lruvec *, enum lru_list, int); > @@ -266,6 +267,11 @@ mem_cgroup_inactive_anon_is_low(struct lruvec *lruvec) > return 1; > } > > +bool mem_cgroup_lruvec_online(struct lruvec *lruvec) > +{ > + return true; > +} > + > static inline unsigned long > mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list lru) > { > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index bfa1a849d113..67c936bbaa13 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -1367,6 +1367,20 @@ int mem_cgroup_inactive_anon_is_low(struct lruvec *lruvec) > return inactive * inactive_ratio < active; > } > > +bool mem_cgroup_lruvec_online(struct lruvec *lruvec) > +{ > + struct mem_cgroup_per_zone *mz; > + struct mem_cgroup *memcg; > + > + if (mem_cgroup_disabled()) > + return true; > + > + mz = container_of(lruvec, struct mem_cgroup_per_zone, lruvec); > + memcg = mz->memcg; > + > + return !!(memcg->css.flags & CSS_ONLINE); > +} > + > #define mem_cgroup_from_counter(counter, member) \ > container_of(counter, struct mem_cgroup, member) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index e29f411b38ac..38173d9a2a87 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1935,8 +1935,12 @@ static void get_scan_count(struct lruvec *lruvec, int swappiness, > * latencies, so it's better to scan a minimum amount there as > * well. > */ > - if (current_is_kswapd() && !zone_reclaimable(zone)) > - force_scan = true; > + if (current_is_kswapd()) { > + if (!zone_reclaimable(zone)) > + force_scan = true; > + if (!mem_cgroup_lruvec_online(lruvec)) > + force_scan = true; > + } > if (!global_reclaim(sc)) > force_scan = true; > > -- > 1.7.10.4 > -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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