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Date:   Wed, 24 Nov 2021 23:18:33 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Peter Oskolkov <posk@posk.io>
Cc:     Ingo Molnar <mingo@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Andy Lutomirski <luto@kernel.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
        Paul Turner <pjt@google.com>, Ben Segall <bsegall@google.com>,
        Peter Oskolkov <posk@google.com>,
        Andrei Vagin <avagin@google.com>, Jann Horn <jannh@google.com>,
        Thierry Delisle <tdelisle@uwaterloo.ca>
Subject: Re: [PATCH v0.9.1 3/6] sched/umcg: implement UMCG syscalls
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 <20211122211327.5931-4-posk@google.com>
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On Mon, Nov 22, 2021 at 01:13:24PM -0800, Peter Oskolkov wrote:
> +die:
> +	pr_warn("%s: killing task %d\n", __func__, current->pid);
> +	force_sig(SIGKILL);

That pr_warn() might need to be pr_warn_ratelimited() in order to no be
a system log DoS.

Because, AFAICT, you can craft userspace to trigger this arbitrarily
often, just spawn a worker and make it misbehave.