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Fri, 28 Jun 2024 15:55:44 +0800 Message-ID: Date: Fri, 28 Jun 2024 15:55:44 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.5.1 Subject: Re: [PATCH -next] mm: memcg: adjust the warning when seq_buf overflows Content-Language: en-US To: Michal Hocko CC: , , , , , , , References: <20240628072333.2496527-1-xiujianfeng@huawei.com> From: xiujianfeng In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.110.112] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpeml500023.china.huawei.com (7.185.36.114) X-Stat-Signature: 8h3sefoecqpweuj3emrwgatzqcoygrzy X-Rspam-User: X-Rspamd-Queue-Id: 7948140008 X-Rspamd-Server: rspam02 X-HE-Tag: 1719561349-659768 X-HE-Meta: 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 mq9k9NHK WV2F8fZS5zyi5SjzAgzdbkcLcAfDw4iaaMiXMWe1nhTW4ZgnM4VmerJJAMAMHnmMhRHJdEgRNF2r3QwpFXEgtp5DAupXU740I9MHjPlCoRnb8onfhPjv4d6bI6vvhoQ4G0OUwNccnZfrTilTLk4JVm0NtqRksQTZp5DMPDVsVO5My6UZwgZUCNa30O8P3yYy5xPni4Jlgmw67VgsfzN3fSJRATAUbfFUB7ep6bg9qog7W1wSs/d7RrdU5+oSTTifqVKg3 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2024/6/28 15:45, Michal Hocko wrote: > On Fri 28-06-24 07:23:33, Xiu Jianfeng wrote: >> 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 >> Signed-off-by: Xiu Jianfeng > > Acked-by: Michal Hocko > > I would just squash this with other patch removing it from > memcg_stat_format. But this is up to you. Thanks, the other patch has already been merged into the -next branch by Andrew. In this situation, I'm not quite clear whether I should send a small separate patch, or squash them and send a v2. If Andrew wants, I can do it. > > Thanks! > >> --- >> 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 >> >