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mm: clean up and clarify lruvec lookup procedure

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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>
This commit is contained in:
Johannes Weiner
2019-11-30 17:55:34 -08:00
committed by Linus Torvalds
parent de3b01506e
commit 867e5e1de1
7 changed files with 35 additions and 34 deletions
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24
include/linux/memcontrol.h
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@@ -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,