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[109.81.86.16]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5861503b52esm610372a12.89.2024.06.28.00.45.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 28 Jun 2024 00:45:21 -0700 (PDT) Date: Fri, 28 Jun 2024 09:45:20 +0200 From: Michal Hocko To: Xiu Jianfeng Cc: hannes@cmpxchg.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, akpm@linux-foundation.org, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH -next] mm: memcg: adjust the warning when seq_buf overflows Message-ID: References: <20240628072333.2496527-1-xiujianfeng@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240628072333.2496527-1-xiujianfeng@huawei.com> X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 341AA100013 X-Stat-Signature: m6crtcs3fuwxpfxsu6sj818uwt5gi4wc X-Rspam-User: X-HE-Tag: 1719560722-230482 X-HE-Meta: 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 uJ9rGdmH ugRynhJ7UHkE6/CSefHyW2e0sMhoXn6ZSPqIL+L2FhlTt/2ci7UHg9Pv2tj/wVERnpMrhjF1qlfRH9amRbG50M4Z6GrYB1Jh7GuS37XEaFekwD5mjpr5Glagxp+4VKOxYxnv9qOdSs3HBN7I87e4DKXIynE+pPApyn5te34pa+MgUBCXcbyvwkjRA9cDRKLyS3mVnxfqUhAXZfn+EHyb38yeKe2l+XEHwzcuFa6qna2XaYMmMVeHDI9+ySwZkAs8phO/hDioWkehVDsg/d+Wgdc9pePeGA8iAZOqtFC3del9e7w1Kq9TtxbsotWlm/Iz/HzoEYIR6R1YvBocIaOE4cZUyQYR3xw2+Jny7caFSnOhruFp62zdzfiFReQMOytGhT7SSlesaG7NKiZy2Met/DW0HW294yGbtgXsu 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 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! > --- > 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 > -- Michal Hocko SUSE Labs