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authorJohannes Weiner <hannes@cmpxchg.org>2019-11-30 17:55:34 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-12-01 12:59:06 -0800
commit867e5e1de14b2b2bde324cdfeec3f3f83eb21424 (patch)
tree22a8f8e2142314de860983c95d89fbe86b39cf1a /include
parentde3b01506ea494b46aab05dc143b69adbf2aaa9d (diff)
mm: clean up and clarify lruvec lookup procedure
There is a per-memcg lruvec and a NUMA node lruvec. Which one is being used is somewhat confusing right now, and it's easy to make mistakes - especially when it comes to global reclaim. How it works: when memory cgroups are enabled, we always use the root_mem_cgroup's per-node lruvecs. When memory cgroups are not compiled in or disabled at runtime, we use pgdat->lruvec. Document that in a comment. Due to the way the reclaim code is generalized, all lookups use the mem_cgroup_lruvec() helper function, and nobody should have to find the right lruvec manually right now. But to avoid future mistakes, rename the pgdat->lruvec member to pgdat->__lruvec and delete the convenience wrapper that suggests it's a commonly accessed member. While in this area, swap the mem_cgroup_lruvec() argument order. The name suggests a memcg operation, yet it takes a pgdat first and a memcg second. I have to double take every time I call this. Fix that. Link: http://lkml.kernel.org/r/20191022144803.302233-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/memcontrol.h24
-rw-r--r--include/linux/mmzone.h15
2 files changed, 20 insertions, 19 deletions
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 239e752a7817..feeb2c76f568 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -385,21 +385,21 @@ mem_cgroup_nodeinfo(struct mem_cgroup *memcg, int nid)
}
/**
- * mem_cgroup_lruvec - get the lru list vector for a node or a memcg zone
- * @node: node of the wanted lruvec
+ * mem_cgroup_lruvec - get the lru list vector for a memcg & node
* @memcg: memcg of the wanted lruvec
*
- * Returns the lru list vector holding pages for a given @node or a given
- * @memcg. This can be the node lruvec, if the memory controller is disabled.
+ * Returns the lru list vector holding pages for a given @memcg &
+ * @node combination. This can be the node lruvec, if the memory
+ * controller is disabled.
*/
-static inline struct lruvec *mem_cgroup_lruvec(struct pglist_data *pgdat,
- struct mem_cgroup *memcg)
+static inline struct lruvec *mem_cgroup_lruvec(struct mem_cgroup *memcg,
+ struct pglist_data *pgdat)
{
struct mem_cgroup_per_node *mz;
struct lruvec *lruvec;
if (mem_cgroup_disabled()) {
- lruvec = node_lruvec(pgdat);
+ lruvec = &pgdat->__lruvec;
goto out;
}
@@ -718,7 +718,7 @@ static inline void __mod_lruvec_page_state(struct page *page,
return;
}
- lruvec = mem_cgroup_lruvec(pgdat, page->mem_cgroup);
+ lruvec = mem_cgroup_lruvec(page->mem_cgroup, pgdat);
__mod_lruvec_state(lruvec, idx, val);
}
@@ -889,16 +889,16 @@ static inline void mem_cgroup_migrate(struct page *old, struct page *new)
{
}
-static inline struct lruvec *mem_cgroup_lruvec(struct pglist_data *pgdat,
- struct mem_cgroup *memcg)
+static inline struct lruvec *mem_cgroup_lruvec(struct mem_cgroup *memcg,
+ struct pglist_data *pgdat)
{
- return node_lruvec(pgdat);
+ return &pgdat->__lruvec;
}
static inline struct lruvec *mem_cgroup_page_lruvec(struct page *page,
struct pglist_data *pgdat)
{
- return &pgdat->lruvec;
+ return &pgdat->__lruvec;
}
static inline bool mm_match_cgroup(struct mm_struct *mm,
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index c7fb21f19edd..cc8232a100bd 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -777,7 +777,13 @@ typedef struct pglist_data {
#endif
/* Fields commonly accessed by the page reclaim scanner */
- struct lruvec lruvec;
+
+ /*
+ * NOTE: THIS IS UNUSED IF MEMCG IS ENABLED.
+ *
+ * Use mem_cgroup_lruvec() to look up lruvecs.
+ */
+ struct lruvec __lruvec;
unsigned long flags;
@@ -800,11 +806,6 @@ typedef struct pglist_data {
#define node_start_pfn(nid) (NODE_DATA(nid)->node_start_pfn)
#define node_end_pfn(nid) pgdat_end_pfn(NODE_DATA(nid))
-static inline struct lruvec *node_lruvec(struct pglist_data *pgdat)
-{
- return &pgdat->lruvec;
-}
-
static inline unsigned long pgdat_end_pfn(pg_data_t *pgdat)
{
return pgdat->node_start_pfn + pgdat->node_spanned_pages;
@@ -842,7 +843,7 @@ static inline struct pglist_data *lruvec_pgdat(struct lruvec *lruvec)
#ifdef CONFIG_MEMCG
return lruvec->pgdat;
#else
- return container_of(lruvec, struct pglist_data, lruvec);
+ return container_of(lruvec, struct pglist_data, __lruvec);
#endif
}