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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Sat, 2 Oct 2021 09:52:49 -0700
Message-ID: <CAHk-=whrLuVEC0x+XzYUNV2de5kM-k39GkJWwviQNuCdZ0nfKg@mail.gmail.com>
Subject: Re: [PATCH] Introduce the pkill_on_warn boot parameter
To:     Alexander Popov <alex.popov@linux.com>
Cc:     Petr Mladek <pmladek@suse.com>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Andrew Morton <akpm@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Joerg Roedel <jroedel@suse.de>,
        Maciej Rozycki <macro@orcam.me.uk>,
        Muchun Song <songmuchun@bytedance.com>,
        Viresh Kumar <viresh.kumar@linaro.org>,
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        Randy Dunlap <rdunlap@infradead.org>,
        Lu Baolu <baolu.lu@linux.intel.com>,
        Kees Cook <keescook@chromium.org>,
        Luis Chamberlain <mcgrof@kernel.org>, Wei Liu <wl@xen.org>,
        John Ogness <john.ogness@linutronix.de>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
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On Sat, Oct 2, 2021 at 4:41 AM Alexander Popov <alex.popov@linux.com> wrote:
>
> And what do you think about the proposed pkill_on_warn?

Honestly, I don't see the point.

If you can reliably trigger the WARN_ON some way, you can probably
cause more problems by fooling some other process to trigger it.

And if it's unintentional, then what does the signal help?

So rather than a "rationale" that makes little sense, I'd like to hear
of an actual _use_ case. That's different. That's somebody actually
_using_ that pkill to good effect for some particular load.

That said, I don't much care in the end. But it sounds like a
pointless option to just introduce yet another behavior to something
that should never happen anyway, and where the actual
honest-to-goodness reason for WARN_ON() existing is already being
fulfilled (ie syzbot has been very effective at flushing things like
that out).

                   Linus