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-rw-r--r--mm/memcontrol.c28
1 files changed, 17 insertions, 11 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index cb1c9dedf9b..194721839cf 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1199,7 +1199,6 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
mz = mem_cgroup_zoneinfo(root, nid, zid);
iter = &mz->reclaim_iter[reclaim->priority];
- last_visited = iter->last_visited;
if (prev && reclaim->generation != iter->generation) {
iter->last_visited = NULL;
goto out_unlock;
@@ -1218,13 +1217,12 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
* is alive.
*/
dead_count = atomic_read(&root->dead_count);
- smp_rmb();
- last_visited = iter->last_visited;
- if (last_visited) {
- if ((dead_count != iter->last_dead_count) ||
- !css_tryget(&last_visited->css)) {
+ if (dead_count == iter->last_dead_count) {
+ smp_rmb();
+ last_visited = iter->last_visited;
+ if (last_visited &&
+ !css_tryget(&last_visited->css))
last_visited = NULL;
- }
}
}
@@ -3141,8 +3139,6 @@ int memcg_update_cache_size(struct kmem_cache *s, int num_groups)
return -ENOMEM;
}
- INIT_WORK(&s->memcg_params->destroy,
- kmem_cache_destroy_work_func);
s->memcg_params->is_root_cache = true;
/*
@@ -4108,8 +4104,6 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype,
if (mem_cgroup_disabled())
return NULL;
- VM_BUG_ON(PageSwapCache(page));
-
if (PageTransHuge(page)) {
nr_pages <<= compound_order(page);
VM_BUG_ON(!PageTransHuge(page));
@@ -4205,6 +4199,18 @@ void mem_cgroup_uncharge_page(struct page *page)
if (page_mapped(page))
return;
VM_BUG_ON(page->mapping && !PageAnon(page));
+ /*
+ * If the page is in swap cache, uncharge should be deferred
+ * to the swap path, which also properly accounts swap usage
+ * and handles memcg lifetime.
+ *
+ * Note that this check is not stable and reclaim may add the
+ * page to swap cache at any time after this. However, if the
+ * page is not in swap cache by the time page->mapcount hits
+ * 0, there won't be any page table references to the swap
+ * slot, and reclaim will free it and not actually write the
+ * page to disk.
+ */
if (PageSwapCache(page))
return;
__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_ANON, false);