From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 34B98C64EAD for ; Tue, 9 Oct 2018 04:48:16 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 74AC620C0A for ; Tue, 9 Oct 2018 04:48:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 74AC620C0A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=c-s.fr Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 42Tl9957BDzF3CX for ; Tue, 9 Oct 2018 15:48:13 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=c-s.fr Authentication-Results: lists.ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=c-s.fr (client-ip=93.17.236.30; helo=pegase1.c-s.fr; envelope-from=christophe.leroy@c-s.fr; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=c-s.fr Received: from pegase1.c-s.fr (pegase1.c-s.fr [93.17.236.30]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 42Tl7J2rs9zF3CP for ; Tue, 9 Oct 2018 15:46:35 +1100 (AEDT) Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 42Tl712hhDz9ttBx; Tue, 9 Oct 2018 06:46:21 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [192.168.12.234]) (amavisd-new, port 10024) with ESMTP id fL7PvXFbq8vy; Tue, 9 Oct 2018 06:46:21 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 42Tl7120Rkz9ttBR; Tue, 9 Oct 2018 06:46:21 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 1B1FE8B775; Tue, 9 Oct 2018 06:46:31 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id oyboibtDw4Se; Tue, 9 Oct 2018 06:46:31 +0200 (CEST) Received: from PO15451 (unknown [192.168.232.3]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 4F9E68B75B; Tue, 9 Oct 2018 06:46:31 +0200 (CEST) Subject: Re: [PATCH v2 3/3] powerpc: machine check interrupt is a non-maskable interrupt To: Nicholas Piggin References: <20170719065912.19183-1-npiggin@gmail.com> <20170719065912.19183-4-npiggin@gmail.com> <30487984-752a-960d-6aae-6571c55c7ba5@c-s.fr> <20181009143241.026f3e7f@roar.ozlabs.ibm.com> From: Christophe LEROY Message-ID: Date: Tue, 9 Oct 2018 06:46:30 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20181009143241.026f3e7f@roar.ozlabs.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mahesh Jagannath Salgaonkar , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Le 09/10/2018 à 06:32, Nicholas Piggin a écrit : > On Mon, 8 Oct 2018 17:39:11 +0200 > Christophe LEROY wrote: > >> Hi Nick, >> >> Le 19/07/2017 à 08:59, Nicholas Piggin a écrit : >>> Use nmi_enter similarly to system reset interrupts. This uses NMI >>> printk NMI buffers and turns off various debugging facilities that >>> helps avoid tripping on ourselves or other CPUs. >>> >>> Signed-off-by: Nicholas Piggin >>> --- >>> arch/powerpc/kernel/traps.c | 9 ++++++--- >>> 1 file changed, 6 insertions(+), 3 deletions(-) >>> >>> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c >>> index 2849c4f50324..6d31f9d7c333 100644 >>> --- a/arch/powerpc/kernel/traps.c >>> +++ b/arch/powerpc/kernel/traps.c >>> @@ -789,8 +789,10 @@ int machine_check_generic(struct pt_regs *regs) >>> >>> void machine_check_exception(struct pt_regs *regs) >>> { >>> - enum ctx_state prev_state = exception_enter(); >>> int recover = 0; >>> + bool nested = in_nmi(); >>> + if (!nested) >>> + nmi_enter(); >> >> This alters preempt_count, then when die() is called >> in_interrupt() returns true allthough the trap didn't happen in >> interrupt, so oops_end() panics for "fatal exception in interrupt" >> instead of gently sending SIGBUS the faulting app. > > Thanks for tracking that down. > >> Any idea on how to fix this ? > > I would say we have to deliver the sigbus by hand. > > if ((user_mode(regs))) > _exception(SIGBUS, regs, BUS_MCEERR_AR, regs->nip); > else > die("Machine check", regs, SIGBUS); > And what about all the other things done by 'die()' ? And what if it is a kernel thread ? In one of my boards, I have a kernel thread regularly checking the HW, and if it gets a machine check I expect it to gently stop and the die notification to be delivered to all registered notifiers. Until before this patch, it was working well. Christophe