Commit cf2b8fbf authored by Vladimir Davydov's avatar Vladimir Davydov Committed by Linus Torvalds
Browse files

memcg: zap memcg_can_account_kmem 



memcg_can_account_kmem() returns true iff

    !mem_cgroup_disabled() && !mem_cgroup_is_root(memcg) &&
                                   memcg_kmem_is_active(memcg);

To begin with the !mem_cgroup_is_root(memcg) check is useless, because one
can't enable kmem accounting for the root cgroup (mem_cgroup_write()
returns EINVAL on an attempt to set the limit on the root cgroup).

Furthermore, the !mem_cgroup_disabled() check also seems to be redundant.
The point is memcg_can_account_kmem() is called from three places:
mem_cgroup_salbinfo_read(), __memcg_kmem_get_cache(), and
__memcg_kmem_newpage_charge().  The latter two functions are only invoked
if memcg_kmem_enabled() returns true, which implies that the memory cgroup
subsystem is enabled.  And mem_cgroup_slabinfo_read() shows the output of
memory.kmem.slabinfo, which won't exist if the memory cgroup is completely
disabled.

So let's substitute all the calls to memcg_can_account_kmem() with plain
memcg_kmem_is_active(), and kill the former.

Signed-off-by: default avatarVladimir Davydov <vdavydov@parallels.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b70a2a21

mm/memcontrol.c

+3 −9
Original line number Original line Diff line number Diff line
@@ -2762,12 +2762,6 @@ static DEFINE_MUTEX(memcg_slab_mutex); 




static DEFINE_MUTEX(activate_kmem_mutex);

static DEFINE_MUTEX(activate_kmem_mutex);





static inline bool memcg_can_account_kmem(struct mem_cgroup *memcg)

{

	return !mem_cgroup_disabled() && !mem_cgroup_is_root(memcg) &&

		memcg_kmem_is_active(memcg);

}



/*

/*

 * This is a bit cumbersome, but it is rarely used and avoids a backpointer

 * This is a bit cumbersome, but it is rarely used and avoids a backpointer

 * in the memcg_cache_params struct.

 * in the memcg_cache_params struct.
@@ -2787,7 +2781,7 @@ static int mem_cgroup_slabinfo_read(struct seq_file *m, void *v) 
	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));

	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));

	struct memcg_cache_params *params;

	struct memcg_cache_params *params;





	if (!memcg_can_account_kmem(memcg))

	if (!memcg_kmem_is_active(memcg))

		return -EIO;

		return -EIO;





	print_slabinfo_header(m);

	print_slabinfo_header(m);
@@ -3164,7 +3158,7 @@ struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep, 
	rcu_read_lock();

	rcu_read_lock();

	memcg = mem_cgroup_from_task(rcu_dereference(current->mm->owner));

	memcg = mem_cgroup_from_task(rcu_dereference(current->mm->owner));





	if (!memcg_can_account_kmem(memcg))

	if (!memcg_kmem_is_active(memcg))

		goto out;

		goto out;





	memcg_cachep = cache_from_memcg_idx(cachep, memcg_cache_id(memcg));

	memcg_cachep = cache_from_memcg_idx(cachep, memcg_cache_id(memcg));
@@ -3249,7 +3243,7 @@ __memcg_kmem_newpage_charge(gfp_t gfp, struct mem_cgroup **_memcg, int order) 




	memcg = get_mem_cgroup_from_mm(current->mm);

	memcg = get_mem_cgroup_from_mm(current->mm);





	if (!memcg_can_account_kmem(memcg)) {

	if (!memcg_kmem_is_active(memcg)) {

		css_put(&memcg->css);

		css_put(&memcg->css);

		return true;

		return true;

	}

	}

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