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Commit 0999821b authored by Glauber Costa's avatar Glauber Costa Committed by Linus Torvalds
Browse files

memcg: replace cgroup_lock with memcg specific memcg_lock 



After the preparation work done in earlier patches, the cgroup_lock can
be trivially replaced with a memcg-specific lock.  This is an automatic
translation at every site where the values involved were queried.

The sites where values are written, however, used to be naturally called
under cgroup_lock.  This is the case for instance in the css_online
callback.  For those, we now need to explicitly add the memcg lock.

With this, all the calls to cgroup_lock outside cgroup core are gone.

Signed-off-by: default avatarGlauber Costa <glommer@parallels.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b5f99b53

mm/memcontrol.c

+21 −18
Original line number Diff line number Diff line
@@ -488,6 +488,13 @@ enum res_type { 
#define MEM_CGROUP_RECLAIM_SHRINK_BIT	0x1

#define MEM_CGROUP_RECLAIM_SHRINK	(1 << MEM_CGROUP_RECLAIM_SHRINK_BIT)



/*

 * The memcg_create_mutex will be held whenever a new cgroup is created.

 * As a consequence, any change that needs to protect against new child cgroups

 * appearing has to hold it as well.

 */

static DEFINE_MUTEX(memcg_create_mutex);



static void mem_cgroup_get(struct mem_cgroup *memcg);

static void mem_cgroup_put(struct mem_cgroup *memcg);
@@ -4778,8 +4785,8 @@ static inline bool __memcg_has_children(struct mem_cgroup *memcg) 
}



/*

 * Must be called with cgroup_lock held, unless the cgroup is guaranteed to be

 * already dead (in mem_cgroup_force_empty(), for instance).  This is different

 * Must be called with memcg_create_mutex held, unless the cgroup is guaranteed

 * to be already dead (as in mem_cgroup_force_empty, for instance).  This is

 * from mem_cgroup_count_children(), in the sense that we don't really care how

 * many children we have; we only need to know if we have any.  It also counts

 * any memcg without hierarchy as infertile.
@@ -4859,7 +4866,7 @@ static int mem_cgroup_hierarchy_write(struct cgroup *cont, struct cftype *cft, 
	if (parent)

		parent_memcg = mem_cgroup_from_cont(parent);



	cgroup_lock();

	mutex_lock(&memcg_create_mutex);



	if (memcg->use_hierarchy == val)

		goto out;
@@ -4882,7 +4889,7 @@ static int mem_cgroup_hierarchy_write(struct cgroup *cont, struct cftype *cft, 
		retval = -EINVAL;



out:

	cgroup_unlock();

	mutex_unlock(&memcg_create_mutex);



	return retval;

}
@@ -4981,14 +4988,8 @@ static int memcg_update_kmem_limit(struct cgroup *cont, u64 val) 
	 *

	 * After it first became limited, changes in the value of the limit are

	 * of course permitted.

	 *

	 * Taking the cgroup_lock is really offensive, but it is so far the only

	 * way to guarantee that no children will appear. There are plenty of

	 * other offenders, and they should all go away. Fine grained locking

	 * is probably the way to go here. When we are fully hierarchical, we

	 * can also get rid of the use_hierarchy check.

	 */

	cgroup_lock();

	mutex_lock(&memcg_create_mutex);

	mutex_lock(&set_limit_mutex);

	if (!memcg->kmem_account_flags && val != RESOURCE_MAX) {

		if (cgroup_task_count(cont) || memcg_has_children(memcg)) {
@@ -5015,7 +5016,7 @@ static int memcg_update_kmem_limit(struct cgroup *cont, u64 val) 
		ret = res_counter_set_limit(&memcg->kmem, val);

out:

	mutex_unlock(&set_limit_mutex);

	cgroup_unlock();

	mutex_unlock(&memcg_create_mutex);



	/*

	 * We are by now familiar with the fact that we can't inc the static
@@ -5396,17 +5397,17 @@ static int mem_cgroup_swappiness_write(struct cgroup *cgrp, struct cftype *cft, 


	parent = mem_cgroup_from_cont(cgrp->parent);



	cgroup_lock();

	mutex_lock(&memcg_create_mutex);



	/* If under hierarchy, only empty-root can set this value */

	if ((parent->use_hierarchy) || memcg_has_children(memcg)) {

		cgroup_unlock();

		mutex_unlock(&memcg_create_mutex);

		return -EINVAL;

	}



	memcg->swappiness = val;



	cgroup_unlock();

	mutex_unlock(&memcg_create_mutex);



	return 0;

}
@@ -5732,16 +5733,16 @@ static int mem_cgroup_oom_control_write(struct cgroup *cgrp, 


	parent = mem_cgroup_from_cont(cgrp->parent);



	cgroup_lock();

	mutex_lock(&memcg_create_mutex);

	/* oom-kill-disable is a flag for subhierarchy. */

	if ((parent->use_hierarchy) || memcg_has_children(memcg)) {

		cgroup_unlock();

		mutex_unlock(&memcg_create_mutex);

		return -EINVAL;

	}

	memcg->oom_kill_disable = val;

	if (!val)

		memcg_oom_recover(memcg);

	cgroup_unlock();

	mutex_unlock(&memcg_create_mutex);

	return 0;

}
@@ -6170,6 +6171,7 @@ mem_cgroup_css_online(struct cgroup *cont) 
	if (!cont->parent)

		return 0;



	mutex_lock(&memcg_create_mutex);

	memcg = mem_cgroup_from_cont(cont);

	parent = mem_cgroup_from_cont(cont->parent);
@@ -6203,6 +6205,7 @@ mem_cgroup_css_online(struct cgroup *cont) 
	}



	error = memcg_init_kmem(memcg, &mem_cgroup_subsys);

	mutex_unlock(&memcg_create_mutex);

	if (error) {

		/*

		 * We call put now because our (and parent's) refcnts