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[195.250.132.146]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a729d71f5acsm31349466b.68.2024.06.27.00.13.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 Jun 2024 00:13:29 -0700 (PDT) Date: Thu, 27 Jun 2024 09:13:29 +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: remove redundant seq_buf_has_overflowed() Message-ID: References: <20240626094232.2432891-1-xiujianfeng@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240626094232.2432891-1-xiujianfeng@huawei.com> X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 8E421C0005 X-Stat-Signature: fbpexefxx4y93ektf94whi9jsa4sshrr X-HE-Tag: 1719472411-328068 X-HE-Meta: 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 qNqqqK/j PIwkQgs2POgv/xwB4iMKy8OFj8NJ+XV1j/Z75yecj+8T6a3TtHAaZ803p/YE4RryKgyT1w3uUU8bSXq+/q6Y0cG6fdB5K9J2CFTdIpGF8TuMDza+1zd3Yl84lbhQcPrisPI6WLWjsYhatip/p2Pnmo0WVUQ2kizL542212Bf52FSJeUbLHNOEaBOAKkCbpW3w2F7vyZ30qzRu6HAu7bxxn9Se/P/FSnyUBMw9bF3aJM3H07TMUwkqC+O5wBENVVat73hrRC8lBlaD9rHWjzzY20SruPVhaTE+/4KFr5OBD0EdlciMVoWZU5zuGu+gzMwQmHfDVt93J66iIStranZ2dG33nFYywgdY4n0g X-Bogosity: Ham, tests=bogofilter, spamicity=0.000002, 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 Wed 26-06-24 09:42:32, Xiu Jianfeng wrote: > Both the end of memory_stat_format() and memcg_stat_format() will call > WARN_ON_ONCE(seq_buf_has_overflowed()). However, memory_stat_format() > is the only caller of memcg_stat_format(), when memcg is on the default > hierarchy, seq_buf_has_overflowed() will be executed twice, so remove > the reduntant one. Shouldn't we rather remove both? Are they giving us anything useful actually? Would a simpl pr_warn be sufficient? Afterall all we care about is to learn that we need to grow the buffer size because our stats do not fit anymore. It is not really important whether that is an OOM or cgroupfs interface path. > Signed-off-by: Xiu Jianfeng > --- > mm/memcontrol.c | 3 --- > 1 file changed, 3 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 974bd160838c..776d22bc66a2 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -1846,9 +1846,6 @@ static void memcg_stat_format(struct mem_cgroup *memcg, struct seq_buf *s) > vm_event_name(memcg_vm_event_stat[i]), > memcg_events(memcg, memcg_vm_event_stat[i])); > } > - > - /* The above should easily fit into one page */ > - WARN_ON_ONCE(seq_buf_has_overflowed(s)); > } > > static void memcg1_stat_format(struct mem_cgroup *memcg, struct seq_buf *s); > -- > 2.34.1 -- Michal Hocko SUSE Labs