Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20211025083315.4752-1-laoar.shao@gmail.com>
In-Reply-To: <20211025083315.4752-1-laoar.shao@gmail.com>
From:   Alexei Starovoitov <alexei.starovoitov@gmail.com>
Date:   Mon, 25 Oct 2021 11:10:09 -0700
Message-ID: <CAADnVQKm0Ljj-w5PbkAu1ugLFnZRRPt-Vk-J7AhXxDD5xVompA@mail.gmail.com>
Subject: Re: [PATCH v6 00/12] extend task comm from 16 to 24
To:     Yafang Shao <laoar.shao@gmail.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Kees Cook <keescook@chromium.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
        Petr Mladek <pmladek@suse.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Valentin Schneider <valentin.schneider@arm.com>,
        "Zhang, Qiang" <qiang.zhang@windriver.com>, robdclark@chromium.org,
        Christian Brauner <christian@brauner.io>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Ingo Molnar <mingo@redhat.com>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        dennis.dalessandro@cornelisnetworks.com,
        mike.marciniszyn@cornelisnetworks.com,
        Doug Ledford <dledford@redhat.com>,
        Jason Gunthorpe <jgg@ziepe.ca>, linux-rdma@vger.kernel.org,
        Network Development <netdev@vger.kernel.org>,
        bpf <bpf@vger.kernel.org>, linux-perf-users@vger.kernel.org,
        Linux-Fsdevel <linux-fsdevel@vger.kernel.org>,
        linux-mm <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        kernel test robot <oliver.sang@intel.com>,
        kbuild test robot <lkp@intel.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Mon, Oct 25, 2021 at 1:33 AM Yafang Shao <laoar.shao@gmail.com> wrote:
>
> There're many truncated kthreads in the kernel, which may make trouble
> for the user, for example, the user can't get detailed device
> information from the task comm.
>
> This patchset tries to improve this problem fundamentally by extending
> the task comm size from 16 to 24. In order to do that, we have to do
> some cleanups first.

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.