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Subject[PATCH 02/14] lru/memcg: move the lruvec->pgdat sync out lru_lock
Date
We are going to move lruvec getting out of lru_lock, the only unsafe
part is lruvec->pgdat syncing when memory node hot pluging.

Splitting out the lruvec->pgdat assignment now and will put it in
lruvec lru_lock protection.

No function changes in this patch now.

Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Chris Down <chris@chrisdown.name>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: cgroups@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
---
include/linux/memcontrol.h | 24 +++++++++++++++++-------
mm/memcontrol.c | 8 +-------
2 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 2cd4359cb38c..95b3d9885ab6 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -359,6 +359,17 @@ void mem_cgroup_cancel_charge(struct page *page, struct mem_cgroup *memcg,
return memcg->nodeinfo[nid];
}

+static void sync_lruvec_pgdat(struct lruvec *lruvec, struct pglist_data *pgdat)
+{
+ /*
+ * Since a node can be onlined after the mem_cgroup was created,
+ * we have to be prepared to initialize lruvec->pgdat here;
+ * and if offlined then reonlined, we need to reinitialize it.
+ */
+ if (!mem_cgroup_disabled() && unlikely(lruvec->pgdat != pgdat))
+ lruvec->pgdat = pgdat;
+}
+
/**
* mem_cgroup_lruvec - get the lru list vector for a node or a memcg zone
* @node: node of the wanted lruvec
@@ -382,13 +393,7 @@ static inline struct lruvec *mem_cgroup_lruvec(struct pglist_data *pgdat,
mz = mem_cgroup_nodeinfo(memcg, pgdat->node_id);
lruvec = &mz->lruvec;
out:
- /*
- * Since a node can be onlined after the mem_cgroup was created,
- * we have to be prepared to initialize lruvec->pgdat here;
- * and if offlined then reonlined, we need to reinitialize it.
- */
- if (unlikely(lruvec->pgdat != pgdat))
- lruvec->pgdat = pgdat;
+ sync_lruvec_pgdat(lruvec, pgdat);
return lruvec;
}

@@ -857,6 +862,11 @@ static inline void mem_cgroup_migrate(struct page *old, struct page *new)
{
}

+static inline void sync_lruvec_pgdat(struct lruvec *lruvec,
+ struct pglist_data *pgdat)
+{
+}
+
static inline struct lruvec *mem_cgroup_lruvec(struct pglist_data *pgdat,
struct mem_cgroup *memcg)
{
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 2792b8ed405f..e8a1b0d95ba8 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1257,13 +1257,7 @@ struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgd
mz = mem_cgroup_page_nodeinfo(memcg, page);
lruvec = &mz->lruvec;
out:
- /*
- * Since a node can be onlined after the mem_cgroup was created,
- * we have to be prepared to initialize lruvec->zone here;
- * and if offlined then reonlined, we need to reinitialize it.
- */
- if (unlikely(lruvec->pgdat != pgdat))
- lruvec->pgdat = pgdat;
+ sync_lruvec_pgdat(lruvec, pgdat);
return lruvec;
}

--
1.8.3.1
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