mm: page_counter: let page_counter_try_charge() return bool

page_counter_try_charge() currently returns 0 on success and -ENOMEM on
failure, which is surprising behavior given the function name.

Make it follow the expected pattern of try_stuff() functions that return a
boolean true to indicate success, or false for failure.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/hugetlb_cgroup.c

@@ -186,7 +186,8 @@ again:
 	}
 	rcu_read_unlock();
 
-	ret = page_counter_try_charge(&h_cg->hugepage[idx], nr_pages, &counter);
+	if (!page_counter_try_charge(&h_cg->hugepage[idx], nr_pages, &counter))
+		ret = -ENOMEM;
 	css_put(&h_cg->css);
 done:
 	*ptr = h_cg;