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Date:   Fri, 24 Sep 2021 15:31:44 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Kees Cook <keescook@chromium.org>
Cc:     Qi Zheng <zhengqi.arch@bytedance.com>,
        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: <YU3TQBIBnrbzWS30@hirez.programming.kicks-ass.net>
References: <20210923233105.4045080-1-keescook@chromium.org>
 <202109231636.C233D6D82@keescook>
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On Thu, Sep 23, 2021 at 04:38:26PM -0700, Kees Cook wrote:
> On Thu, Sep 23, 2021 at 04:31:05PM -0700, Kees Cook wrote:

> If the fair scheduler would actually benefit from still using get_wchan,
> I think this patch:
> https://lore.kernel.org/all/20210831083625.59554-1-zhengqi.arch@bytedance.com/
> should still be applied too.
> 
> If not, we can rip get_wchan() out completely (across all
> architectures).

The scheduler doesn't care, it's kernel/profile.c and please kill that
right along with wchan, good riddance.