From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 9A0FE1A1A45 for ; Wed, 22 Jul 2015 21:40:07 +1000 (AEST) Message-ID: <55AF8111.4080905@redhat.com> Date: Wed, 22 Jul 2015 13:40:01 +0200 From: Thomas Huth MIME-Version: 1.0 To: Michael Ellerman , linuxppc-dev@lists.ozlabs.org, nfont@linux.vnet.ibm.com CC: paulus@samba.org, anton@samba.org, kvm-ppc@vger.kernel.org Subject: Re: powerpc/rtas: Introduce rtas_get_sensor_fast() for IRQ handlers References: <20150722112527.B36E01402C8@ozlabs.org> In-Reply-To: <20150722112527.B36E01402C8@ozlabs.org> Content-Type: text/plain; charset=utf-8 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 22/07/15 13:25, Michael Ellerman wrote: > On Fri, 2015-17-07 at 10:46:58 UTC, Thomas Huth wrote: >> The EPOW interrupt handler uses rtas_get_sensor(), which in turn >> uses rtas_busy_delay() to wait for RTAS becoming ready in case it >> is necessary. But rtas_busy_delay() is annotated with might_sleep() >> and thus may not be used by interrupts handlers like the EPOW handler! >> This leads to the following BUG when CONFIG_DEBUG_ATOMIC_SLEEP is >> enabled: > > When did we break this? Hi Michael, the bug has been introduced by commit 587f83e8dd50d22bc0c62e32ec49fd31 ("powerpc/pseries: Use rtas_get_sensor in RAS code") which switched the EPOW handler to use rtas_get_sensor() instead of using rtas_call directly. Also have a look at this thread here: http://www.spinics.net/lists/kvm-ppc/msg10768.html Thomas