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Message-ID: <e368f2c848d77fbc8d259f44e2055fe469c219cf.camel@gmx.de>
Subject: Re: 'perf test sigtrap' failing on PREEMPT_RT_FULL
From:   Mike Galbraith <efault@gmx.de>
To:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Marco Elver <elver@google.com>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        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>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date:   Wed, 26 Jul 2023 08:10:45 +0200
In-Reply-To: <ZMAtZ2t43GXoF6tM@kernel.org>
References: <ZMAtZ2t43GXoF6tM@kernel.org>
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Precedence: bulk

On Tue, 2023-07-25 at 17:15 -0300, Arnaldo Carvalho de Melo wrote:
> Hi Marco, Peter,
>
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0I got a report that 'per=
f test sigtrap' test failed on a
> PREEMPT_RT_FULL kernel, one that had up to:
>
> commit 97ba62b278674293762c3d91f724f1bb922f04e0
> Author: Marco Elver <elver@google.com>
> Date:=C2=A0=C2=A0 Thu Apr 8 12:36:01 2021 +0200
>
> =C2=A0=C2=A0=C2=A0 perf: Add support for SIGTRAP on perf events
> ...

> [=C2=A0=C2=A0 52.848925] BUG: scheduling while atomic: perf/6549/0x00000=
002

Had bf9ad37dc8a not been reverted due to insufficient beauty, you could
trivially make the sigtrap test a happy camper (wart tested in tip-rt).

	-Mike

@@ -1829,6 +1869,9 @@ int send_sig_perf(void __user *addr, u32
 				     TRAP_PERF_FLAG_ASYNC :
 				     0;

+	if (force_sig_delayed(&info, current))
+		return 0;
+
 	return send_sig_info(info.si_signo, &info, current);
 }