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;
Date:   Fri, 24 Sep 2021 15:29:55 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Kees Cook <keescook@chromium.org>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Vito Caputo <vcaputo@pengaru.com>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>, Jens Axboe <axboe@kernel.dk>,
        Mark Rutland <mark.rutland@arm.com>,
        Stefan Metzmacher <metze@samba.org>,
        Andy Lutomirski <luto@kernel.org>,
        Lai Jiangshan <laijs@linux.alibaba.com>,
        Christian Brauner <christian.brauner@ubuntu.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        "Kenta.Tada@sony.com" <Kenta.Tada@sony.com>,
        Daniel Bristot de Oliveira <bristot@redhat.com>,
        Michael =?iso-8859-1?Q?Wei=DF?= 
        <michael.weiss@aisec.fraunhofer.de>,
        Anand K Mistry <amistry@google.com>,
        Alexey Gladkov <legion@kernel.org>,
        Michal Hocko <mhocko@suse.com>, Helge Deller <deller@gmx.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Andrea Righi <andrea.righi@canonical.com>,
        Ohhoon Kwon <ohoono.kwon@samsung.com>,
        Kalesh Singh <kaleshsingh@google.com>,
        YiFei Zhu <yifeifz2@illinois.edu>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        linux-kernel@vger.kernel.org, x86@kernel.org,
        linux-fsdevel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH] proc: Disable /proc/$pid/wchan
Message-ID: <YU3S0/+DCnanQwRr@hirez.programming.kicks-ass.net>
References: <20210923233105.4045080-1-keescook@chromium.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20210923233105.4045080-1-keescook@chromium.org>
Precedence: bulk

On Thu, Sep 23, 2021 at 04:31:05PM -0700, Kees Cook wrote:

> This leaves kernel/sched/fair.c as the only user of get_wchan(). But
> again, since this was broken for 4 years, was this profiling logic
> actually doing anything useful?

Unlikely, I proposed removing the whole kernel/profile.c thing a while
back, but some people complained that it would make it 'hard' to profile
early boot.

IMO this not actually working right seems another argument for killing
that too :-)