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From:   Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To:     Mike Galbraith <efault@gmx.de>,
        Peter Zijlstra <peterz@infradead.org>
Cc:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Marco Elver <elver@google.com>, linux-rt-users@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Juri Lelli <juri.lelli@redhat.com>,
        Clark Williams <williams@redhat.com>,
        ThomasGleixner <tglx@linutronix.de>
Subject: Re: 'perf test sigtrap' failing on PREEMPT_RT_FULL
Message-ID: <20230728150718.8odZX-jD@linutronix.de>
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 <e368f2c848d77fbc8d259f44e2055fe469c219cf.camel@gmx.de>
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On 2023-07-26 08:10:45 [+0200], Mike Galbraith wrote:
> > [=C2=A0=C2=A0 52.848925] BUG: scheduling while atomic: perf/6549/0x0000=
0002
>=20
> Had bf9ad37dc8a not been reverted due to insufficient beauty, you could
> trivially make the sigtrap test a happy camper (wart tested in tip-rt).

Thank you for the pointer Mike.

I guess we need this preempt_disable_notrace() in perf_pending_task()
due to context accounting in get_recursion_context(). Would a
migrate_disable() be sufficient or could we send the signal outside of
the preempt-disabled block?

This is also used in perf_pending_irq() and on PREEMPT_RT this is
invoked from softirq context which is preemptible.

Sebastian