1 files changed, 9 insertions, 13 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c65751ab4516..b69979c9ced5 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1490,14 +1490,12 @@ static const unsigned int memcg_vm_event_stat[] = {
 #endif
 };
 
-static char *memory_stat_format(struct mem_cgroup *memcg)
+static void memory_stat_format(struct mem_cgroup *memcg, char *buf, int bufsize)
 {
 	struct seq_buf s;
 	int i;
 
-	seq_buf_init(&s, kmalloc(PAGE_SIZE, GFP_KERNEL), PAGE_SIZE);
-	if (!s.buffer)
-		return NULL;
+	seq_buf_init(&s, buf, bufsize);
 
 	/*
 	 * Provide statistics on the state of the memory subsystem as
@@ -1539,8 +1537,6 @@ static char *memory_stat_format(struct mem_cgroup *memcg)
 
 	/* The above should easily fit into one page */
 	WARN_ON_ONCE(seq_buf_has_overflowed(&s));
-
-	return s.buffer;
 }
 
 #define K(x) ((x) << (PAGE_SHIFT-10))
@@ -1576,7 +1572,10 @@ void mem_cgroup_print_oom_context(struct mem_cgroup *memcg, struct task_struct *
  */
 void mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg)
 {
-	char *buf;
+	/* Use static buffer, for the caller is holding oom_lock. */
+	static char buf[PAGE_SIZE];
+
+	lockdep_assert_held(&oom_lock);
 
 	pr_info("memory: usage %llukB, limit %llukB, failcnt %lu\n",
 		K((u64)page_counter_read(&memcg->memory)),
@@ -1597,11 +1596,8 @@ void mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg)
 	pr_info("Memory cgroup stats for ");
 	pr_cont_cgroup_path(memcg->css.cgroup);
 	pr_cont(":");
-	buf = memory_stat_format(memcg);
-	if (!buf)
-		return;
+	memory_stat_format(memcg, buf, sizeof(buf));
 	pr_info("%s", buf);
-	kfree(buf);
 }
 
 /*
@@ -6405,11 +6401,11 @@ static int memory_events_local_show(struct seq_file *m, void *v)
 static int memory_stat_show(struct seq_file *m, void *v)
 {
 	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
-	char *buf;
+	char *buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 
-	buf = memory_stat_format(memcg);
 	if (!buf)
 		return -ENOMEM;
+	memory_stat_format(memcg, buf, PAGE_SIZE);
 	seq_puts(m, buf);
 	kfree(buf);
 	return 0;