From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <owner-linux-mm@kvack.org>
X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on
	aws-us-west-2-korg-lkml-1.web.codeaurora.org
Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17])
	by smtp.lore.kernel.org (Postfix) with ESMTP id 1BD81C77B73
	for <linux-mm@archiver.kernel.org>; Fri,  5 May 2023 03:46:53 +0000 (UTC)
Received: by kanga.kvack.org (Postfix)
	id 5392E6B0075; Thu,  4 May 2023 23:46:52 -0400 (EDT)
Received: by kanga.kvack.org (Postfix, from userid 40)
	id 4E91F6B0078; Thu,  4 May 2023 23:46:52 -0400 (EDT)
X-Delivered-To: int-list-linux-mm@kvack.org
Received: by kanga.kvack.org (Postfix, from userid 63042)
	id 3FF3D6B007B; Thu,  4 May 2023 23:46:52 -0400 (EDT)
X-Delivered-To: linux-mm@kvack.org
Received: from out-38.mta0.migadu.com (out-38.mta0.migadu.com [91.218.175.38])
	by kanga.kvack.org (Postfix) with ESMTP id 212A36B0075
	for <linux-mm@kvack.org>; Thu,  4 May 2023 23:46:52 -0400 (EDT)
Content-Type: text/plain;
	charset=us-ascii
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1;
	t=1683258410;
	h=from:from:reply-to:subject:subject:date:date:message-id:message-id:
	 to:to:cc:cc:mime-version:mime-version:content-type:content-type:
	 content-transfer-encoding:content-transfer-encoding:
	 in-reply-to:in-reply-to:references:references;
	bh=QdstHLLK2gjOImYQV2bW8W6qJ+VMebC2r6lpW7ASjOQ=;
	b=xpmr4J6VcuQA8arCmDuI/+V4og63KJIFBlBzrrrblGmtHqWON1ivEOMglN2h2Qg1/o2CmT
	PbGxWGdhKcG8mr/PRQxdIZQ0x2lMKuu0yKmnKqz6/P6PSOSqzbU0b2CJ1QqGfpf6owumUc
	JiLrELiAIJ/U3ooS/lf+LknWuujeGds=
MIME-Version: 1.0
Subject: Re: [PATCH v2 1/2] memcg: use seq_buf_do_printk() with
 mem_cgroup_print_oom_meminfo()
X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers.
From: Muchun Song <muchun.song@linux.dev>
In-Reply-To: <20230428132406.2540811-2-yosryahmed@google.com>
Date: Fri, 5 May 2023 11:46:10 +0800
Cc: Johannes Weiner <hannes@cmpxchg.org>,
 Michal Hocko <mhocko@kernel.org>,
 Roman Gushchin <roman.gushchin@linux.dev>,
 Shakeel Butt <shakeelb@google.com>,
 Andrew Morton <akpm@linux-foundation.org>,
 Sergey Senozhatsky <senozhatsky@chromium.org>,
 Steven Rostedt <rostedt@goodmis.org>,
 Petr Mladek <pmladek@suse.com>,
 Chris Li <chrisl@kernel.org>,
 cgroups@vger.kernel.org,
 Linux Memory Management List <linux-mm@kvack.org>,
 linux-kernel@vger.kernel.org,
 Michal Hocko <mhocko@suse.com>
Content-Transfer-Encoding: 7bit
Message-Id: <5BE37965-9A20-4743-A2BC-E407D89C53D1@linux.dev>
References: <20230428132406.2540811-1-yosryahmed@google.com>
 <20230428132406.2540811-2-yosryahmed@google.com>
To: Yosry Ahmed <yosryahmed@google.com>
X-Migadu-Flow: FLOW_OUT
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: <linux-mm.kvack.org>



> On Apr 28, 2023, at 21:24, Yosry Ahmed <yosryahmed@google.com> wrote:
> 
> Currently, we format all the memcg stats into a buffer in
> mem_cgroup_print_oom_meminfo() and use pr_info() to dump it to the logs.
> However, this buffer is large in size. Although it is currently working
> as intended, ther is a dependency between the memcg stats buffer and the
> printk record size limit.
> 
> If we add more stats in the future and the buffer becomes larger than
> the printk record size limit, or if the prink record size limit is
> reduced, the logs may be truncated.
> 
> It is safer to use seq_buf_do_printk(), which will automatically break
> up the buffer at line breaks and issue small printk() calls.
> 
> Refactor the code to move the seq_buf from memory_stat_format() to its
> callers, and use seq_buf_do_printk() to print the seq_buf in
> mem_cgroup_print_oom_meminfo().
> 
> Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
> Acked-by: Michal Hocko <mhocko@suse.com>
> Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>

Reviewed-by: Muchun Song <songmuchun@bytedance.com>

Thanks.