linux-kernel - [PATCH -next] mm: memcg: adjust the warning when seq

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Date: Fri, 28 Jun 2024 07:23:33 +0000
From: Xiu Jianfeng <xiujianfeng@...wei.com>
To: <hannes@...xchg.org>, <mhocko@...nel.org>, <roman.gushchin@...ux.dev>,
	<shakeel.butt@...ux.dev>, <muchun.song@...ux.dev>,
	<akpm@...ux-foundation.org>
CC: <cgroups@...r.kernel.org>, <linux-mm@...ck.org>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH -next] mm: memcg: adjust the warning when seq_buf overflows

Currently it uses WARN_ON_ONCE() if seq_buf overflows when user reads
memory.stat, the only advantage of WARN_ON_ONCE is that the splat is
so verbose that it gets noticed. And also it panics the system if
panic_on_warn is enabled. It seems like the warning is just an over
reaction and a simple pr_warn should just achieve the similar effect.

Suggested-by: Michal Hocko <mhocko@...e.com>
Signed-off-by: Xiu Jianfeng <xiujianfeng@...wei.com>
---
 mm/memcontrol.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c251bbe35f4b..8e5590ac43d7 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1484,7 +1484,8 @@ static void memory_stat_format(struct mem_cgroup *memcg, struct seq_buf *s)
 		memcg_stat_format(memcg, s);
 	else
 		memcg1_stat_format(memcg, s);
-	WARN_ON_ONCE(seq_buf_has_overflowed(s));
+	if (seq_buf_has_overflowed(s))
+		pr_warn("%s: Warning, stat buffer overflow, please report\n", __func__);
 }
 
 /**
-- 
2.34.1