Ryo Tsuruta wrote:
+static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
+ gfp_t gfp_mask, enum charge_type ctype,
+ struct mem_cgroup *memcg)
+{
+ struct page_cgroup *pc;
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR
+ struct mem_cgroup *mem;
+ unsigned long flags;
+ unsigned long nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
+ struct mem_cgroup_per_zone *mz;
+#endif /* CONFIG_CGROUP_MEM_RES_CTLR */
+
+ pc = kmem_cache_alloc(page_cgroup_cache, gfp_mask);
+ if (unlikely(pc == NULL))
+ goto err;
+
+ /*
+ * We always charge the cgroup the mm_struct belongs to.
+ * The mm_struct's mem_cgroup changes on task migration if the
+ * thread group leader migrates. It's possible that mm is not
+ * set, if so charge the init_mm (happens for pagecache usage).
+ */
+ if (likely(!memcg)) {
+ rcu_read_lock();
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR
+ mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
+ /*
+ * For every charge from the cgroup, increment reference count
+ */
+ css_get(&mem->css);
+#endif /* CONFIG_CGROUP_MEM_RES_CTLR */
+ rcu_read_unlock();
+ } else {
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR
+ mem = memcg;
+ css_get(&memcg->css);
+#endif /* CONFIG_CGROUP_MEM_RES_CTLR */
+ }
+
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR
+ while (res_counter_charge(&mem->res, PAGE_SIZE)) {
+ if (!(gfp_mask & __GFP_WAIT))
+ goto out;
+
+ if (try_to_free_mem_cgroup_pages(mem, gfp_mask))
+ continue;
+
+ /*
+ * try_to_free_mem_cgroup_pages() might not give us a full
+ * picture of reclaim. Some pages are reclaimed and might be
+ * moved to swap cache or just unmapped from the cgroup.
+ * Check the limit again to see if the reclaim reduced the
+ * current usage of the cgroup before giving up
+ */
+ if (res_counter_check_under_limit(&mem->res))
+ continue;
+
+ if (!nr_retries--) {
+ mem_cgroup_out_of_memory(mem, gfp_mask);
+ goto out;
+ }
+ }
+ pc->mem_cgroup = mem;
+#endif /* CONFIG_CGROUP_MEM_RES_CTLR */
you can remove some ifdefs doing:
#ifdef CONFIG_CGROUP_MEM_RES_CTLR
if (likely(!memcg)) {
rcu_read_lock();
mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
/*
* For every charge from the cgroup, increment reference count
*/
css_get(&mem->css);
rcu_read_unlock();
} else {
mem = memcg;
css_get(&memcg->css);
}
while (res_counter_charge(&mem->res, PAGE_SIZE)) {
if (!(gfp_mask & __GFP_WAIT))
goto out;
if (try_to_free_mem_cgroup_pages(mem, gfp_mask))
continue;
/*
* try_to_free_mem_cgroup_pages() might not give us a full
* picture of reclaim. Some pages are reclaimed and might be
* moved to swap cache or just unmapped from the cgroup.
* Check the limit again to see if the reclaim reduced the
* current usage of the cgroup before giving up
*/
if (res_counter_check_under_limit(&mem->res))
continue;
if (!nr_retries--) {
mem_cgroup_out_of_memory(mem, gfp_mask);
goto out;
}
}
pc->mem_cgroup = mem;
#endif /* CONFIG_CGROUP_MEM_RES_CTLR */
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