The patch titled
Subject: mm/memcg: unify swap and memsw page counters
has been added to the -mm tree. Its filename is
mm-memcg-unify-swap-and-memsw-page-counters.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-memcg-unify-swap-and-memsw-page-counters.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-memcg-unify-swap-and-memsw-page-counters.patch
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------------------------------------------------------
From: Waiman Long <longman@xxxxxxxxxx>
Subject: 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.
Link: https://lkml.kernel.org/r/20200914024452.19167-4-longman@xxxxxxxxxx
Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
Cc: Chris Down <chris@xxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Roman Gushchin <guro@xxxxxx>
Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Cc: Yafang Shao <laoar.shao@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/memcontrol.h | 13 ++++++++-----
mm/memcontrol.c | 3 ---
2 files changed, 8 insertions(+), 8 deletions(-)
--- a/include/linux/memcontrol.h~mm-memcg-unify-swap-and-memsw-page-counters
+++ a/include/linux/memcontrol.h
@@ -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;
--- a/mm/memcontrol.c~mm-memcg-unify-swap-and-memsw-page-counters
+++ a/mm/memcontrol.c
@@ -5293,13 +5293,11 @@ mem_cgroup_css_alloc(struct cgroup_subsy
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);
/*
@@ -5428,7 +5426,6 @@ static void mem_cgroup_css_reset(struct
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);
_
Patches currently in -mm which might be from longman@xxxxxxxxxx are
mm-memcg-clean-up-obsolete-enum-charge_type.patch
mm-memcg-simplify-mem_cgroup_get_max.patch
mm-memcg-unify-swap-and-memsw-page-counters.patch
