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authorGlauber Costa <glommer@parallels.com>2013-02-23 04:34:55 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2013-02-24 05:50:18 +0400
commit0999821b1d08f69e3879eb8fa0d28c4aba82ab5e (patch)
tree5a985ef3b378ede5c7008ecfaceca9d1d3169ea8 /mm
parentb5f99b537d047072bd50ff5c51000613eb537be8 (diff)
downloadlinux-0999821b1d08f69e3879eb8fa0d28c4aba82ab5e.tar.xz
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: Glauber Costa <glommer@parallels.com> Acked-by: Michal 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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/memcontrol.c39
1 files changed, 21 insertions, 18 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 2bc3fbe93154..46cdaef78b01 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -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