memcg: fix destination cgroup leak on task charges migration

[cascardo/linux.git] / mm / memcontrol.c

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index ef91e85..851924f 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3043,18 +3043,6 @@ static int mem_cgroup_move_swap_account(swp_entry_t entry,
        if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
                mem_cgroup_swap_statistics(from, false);
                mem_cgroup_swap_statistics(to, true);
-               /*
-                * This function is only called from task migration context now.
-                * It postpones page_counter and refcount handling till the end
-                * of task migration(mem_cgroup_clear_mc()) for performance
-                * improvement. But we cannot postpone css_get(to)  because if
-                * the process that has been moved to @to does swap-in, the
-                * refcount of @to might be decreased to 0.
-                *
-                * We are in attach() phase, so the cgroup is guaranteed to be
-                * alive, so we can just call css_get().
-                */
-               css_get(&to->css);
                return 0;
        }
        return -EINVAL;
@@ -4679,6 +4667,7 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
        if (parent_css == NULL) {
                root_mem_cgroup = memcg;
                page_counter_init(&memcg->memory, NULL);
+               memcg->soft_limit = PAGE_COUNTER_MAX;
                page_counter_init(&memcg->memsw, NULL);
                page_counter_init(&memcg->kmem, NULL);
        }
@@ -4724,6 +4713,7 @@ mem_cgroup_css_online(struct cgroup_subsys_state *css)
 
        if (parent->use_hierarchy) {
                page_counter_init(&memcg->memory, &parent->memory);
+               memcg->soft_limit = PAGE_COUNTER_MAX;
                page_counter_init(&memcg->memsw, &parent->memsw);
                page_counter_init(&memcg->kmem, &parent->kmem);
 
@@ -4733,6 +4723,7 @@ mem_cgroup_css_online(struct cgroup_subsys_state *css)
                 */
        } else {
                page_counter_init(&memcg->memory, NULL);
+               memcg->soft_limit = PAGE_COUNTER_MAX;
                page_counter_init(&memcg->memsw, NULL);
                page_counter_init(&memcg->kmem, NULL);
                /*
@@ -4807,7 +4798,7 @@ static void mem_cgroup_css_reset(struct cgroup_subsys_state *css)
        mem_cgroup_resize_limit(memcg, PAGE_COUNTER_MAX);
        mem_cgroup_resize_memsw_limit(memcg, PAGE_COUNTER_MAX);
        memcg_update_kmem_limit(memcg, PAGE_COUNTER_MAX);
-       memcg->soft_limit = 0;
+       memcg->soft_limit = PAGE_COUNTER_MAX;
 }
 
 #ifdef CONFIG_MMU