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mm: memcontrol: zap memcg_kmem_online helper 

As kmem accounting is now either enabled for all cgroups or disabled
system-wide, there's no point in having memcg_kmem_online() helper -
instead one can use memcg_kmem_enabled() and mem_cgroup_online(), as
shrink_slab() now does.

There are only two places left where this helper is used -
__memcg_kmem_charge() and memcg_create_kmem_cache().  The former can
only be called if memcg_kmem_enabled() returned true.  Since the cgroup
it operates on is online, mem_cgroup_is_root() check will be enough.

memcg_create_kmem_cache() can't use mem_cgroup_online() helper instead
of memcg_kmem_online(), because it relies on the fact that in
memcg_offline_kmem() memcg->kmem_state is changed before
memcg_deactivate_kmem_caches() is called, but there we can just
open-code the check.

Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hifive-unleashed-5.1
Vladimir Davydov 2016-03-17 14:18:33 -07:00 committed by Linus Torvalds
parent 0fc9f58a90
commit b6ecd2dea4
3 changed files with 2 additions and 12 deletions
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10
include/linux/memcontrol.h
View File

@ -795,11 +795,6 @@ static inline bool memcg_kmem_enabled(void)
return static_branch_unlikely(&memcg_kmem_enabled_key);
}
static inline bool memcg_kmem_online(struct mem_cgroup *memcg)
{
return memcg->kmem_state == KMEM_ONLINE;
}
/*
* In general, we'll do everything in our power to not incur in any overhead
* for non-memcg users for the kmem functions. Not even a function call, if we
@ -909,11 +904,6 @@ static inline bool memcg_kmem_enabled(void)
return false;
}
static inline bool memcg_kmem_online(struct mem_cgroup *memcg)
{
return false;
}
static inline int memcg_kmem_charge(struct page *page, gfp_t gfp, int order)
{
return 0;

2
mm/memcontrol.c
View File

@ -2346,7 +2346,7 @@ int __memcg_kmem_charge(struct page *page, gfp_t gfp, int order)
int ret = 0;
memcg = get_mem_cgroup_from_mm(current->mm);
if (memcg_kmem_online(memcg))
if (!mem_cgroup_is_root(memcg))
ret = __memcg_kmem_charge_memcg(page, gfp, order, memcg);
css_put(&memcg->css);
return ret;

2
mm/slab_common.c
View File

@ -510,7 +510,7 @@ void memcg_create_kmem_cache(struct mem_cgroup *memcg,
* The memory cgroup could have been offlined while the cache
* creation work was pending.
*/
if (!memcg_kmem_online(memcg))
if (memcg->kmem_state != KMEM_ONLINE)
goto out_unlock;
idx = memcg_cache_id(memcg);