Commit bd0b230f authored by Waiman Long's avatar Waiman Long Committed by Linus Torvalds

mm/memcg: unify swap and memsw page counters

The swap page counter is v2 only while memsw is v1 only.  As v1 and v2
controllers cannot be active at the same time, there is no point to keep
both swap and memsw page counters in mem_cgroup.  The previous patch has
made sure that memsw page counter is updated and accessed only when in v1
code paths.  So it is now safe to alias the v1 memsw page counter to v2
swap page counter.  This saves 14 long's in the size of mem_cgroup.  This
is a saving of 112 bytes for 64-bit archs.

While at it, also document which page counters are used in v1 and/or v2.
Signed-off-by: default avatarWaiman Long <longman@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarShakeel Butt <shakeelb@google.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Cc: Chris Down <chris@chrisdown.name>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Yafang Shao <laoar.shao@gmail.com>
Link: https://lkml.kernel.org/r/20200914024452.19167-4-longman@redhat.comSigned-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8d387a5f
......@@ -215,13 +215,16 @@ struct mem_cgroup {
struct mem_cgroup_id id;
/* Accounted resources */
struct page_counter memory;
struct page_counter swap;
struct page_counter memory; /* Both v1 & v2 */
union {
struct page_counter swap; /* v2 only */
struct page_counter memsw; /* v1 only */
};
/* Legacy consumer-oriented counters */
struct page_counter memsw;
struct page_counter kmem;
struct page_counter tcpmem;
struct page_counter kmem; /* v1 only */
struct page_counter tcpmem; /* v1 only */
/* Range enforcement for interrupt charges */
struct work_struct high_work;
......
......@@ -5295,13 +5295,11 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
memcg->use_hierarchy = true;
page_counter_init(&memcg->memory, &parent->memory);
page_counter_init(&memcg->swap, &parent->swap);
page_counter_init(&memcg->memsw, &parent->memsw);
page_counter_init(&memcg->kmem, &parent->kmem);
page_counter_init(&memcg->tcpmem, &parent->tcpmem);
} else {
page_counter_init(&memcg->memory, NULL);
page_counter_init(&memcg->swap, NULL);
page_counter_init(&memcg->memsw, NULL);
page_counter_init(&memcg->kmem, NULL);
page_counter_init(&memcg->tcpmem, NULL);
/*
......@@ -5430,7 +5428,6 @@ static void mem_cgroup_css_reset(struct cgroup_subsys_state *css)
page_counter_set_max(&memcg->memory, PAGE_COUNTER_MAX);
page_counter_set_max(&memcg->swap, PAGE_COUNTER_MAX);
page_counter_set_max(&memcg->memsw, PAGE_COUNTER_MAX);
page_counter_set_max(&memcg->kmem, PAGE_COUNTER_MAX);
page_counter_set_max(&memcg->tcpmem, PAGE_COUNTER_MAX);
page_counter_set_min(&memcg->memory, 0);
......
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