diff options
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/memcontrol.c | 39 |
1 files changed, 21 insertions, 18 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 2bc3fbe9315..46cdaef78b0 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 |