From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9F6ECC433FE for ; Mon, 25 Oct 2021 21:05:12 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 16EC761076 for ; Mon, 25 Oct 2021 21:05:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 16EC761076 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id A3834940009; Mon, 25 Oct 2021 17:05:11 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9E786940007; Mon, 25 Oct 2021 17:05:11 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 88AB0940009; Mon, 25 Oct 2021 17:05:11 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0059.hostedemail.com [216.40.44.59]) by kanga.kvack.org (Postfix) with ESMTP id 7623E940007 for ; Mon, 25 Oct 2021 17:05:11 -0400 (EDT) Received: from smtpin19.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 34B9B26DFC for ; Mon, 25 Oct 2021 21:05:11 +0000 (UTC) X-FDA: 78736190022.19.B846F05 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf17.hostedemail.com (Postfix) with ESMTP id C4307F00038D for ; Mon, 25 Oct 2021 21:05:10 +0000 (UTC) Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8C80961073; Mon, 25 Oct 2021 21:05:06 +0000 (UTC) Date: Mon, 25 Oct 2021 17:05:03 -0400 From: Steven Rostedt To: Alexei Starovoitov Cc: Yafang Shao , Andrew Morton , Kees Cook , Mathieu Desnoyers , Arnaldo Carvalho de Melo , Petr Mladek , Peter Zijlstra , Alexander Viro , Valentin Schneider , "Zhang, Qiang" , robdclark@chromium.org, Christian Brauner , Dietmar Eggemann , Ingo Molnar , Juri Lelli , Vincent Guittot , "David S. Miller" , Jakub Kicinski , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , dennis.dalessandro@cornelisnetworks.com, mike.marciniszyn@cornelisnetworks.com, Doug Ledford , Jason Gunthorpe , linux-rdma@vger.kernel.org, Network Development , bpf , linux-perf-users@vger.kernel.org, Linux-Fsdevel , linux-mm , LKML , kernel test robot , kbuild test robot Subject: Re: [PATCH v6 00/12] extend task comm from 16 to 24 Message-ID: <20211025170503.59830a43@gandalf.local.home> In-Reply-To: References: <20211025083315.4752-1-laoar.shao@gmail.com> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: h7yfjndi9h7xkgjmyogsqgxcsjia994y Authentication-Results: imf17.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf17.hostedemail.com: domain of "SRS0=n7bq=PN=goodmis.org=rostedt@kernel.org" designates 198.145.29.99 as permitted sender) smtp.mailfrom="SRS0=n7bq=PN=goodmis.org=rostedt@kernel.org" X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: C4307F00038D X-HE-Tag: 1635195910-135555 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: On Mon, 25 Oct 2021 11:10:09 -0700 Alexei Starovoitov wrote: > It looks like a churn that doesn't really address the problem. > If we were to allow long names then make it into a pointer and use 16 byte > as an optimized storage for short names. Any longer name would be a pointer. > In other words make it similar to dentry->d_iname. That would be quite a bigger undertaking too, as it is assumed throughout the kernel that the task->comm is TASK_COMM_LEN and is nul terminated. And most locations that save the comm simply use a fixed size string of TASK_COMM_LEN. Not saying its not feasible, but it would require a lot more analysis of the impact by changing such a fundamental part of task struct from a static to something requiring allocation. Unless you are suggesting that we truncate like normal the 16 byte names (to a max of 15 characters), and add a way to hold the entire name for those locations that understand it. -- Steve