Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1754918AbbKXUph (ORCPT <rfc822;w@1wt.eu>);
	Tue, 24 Nov 2015 15:45:37 -0500
Received: from smtprelay0097.hostedemail.com ([216.40.44.97]:60581 "EHLO
	smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL)
	by vger.kernel.org with ESMTP id S1754726AbbKXUpc (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Tue, 24 Nov 2015 15:45:32 -0500
X-Session-Marker: 726F737465647440676F6F646D69732E6F7267
X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,rostedt@goodmis.org,:::::::::::::::::::::::::::::::::::,RULES_HIT:41:355:379:541:599:800:960:973:988:989:1183:1260:1277:1311:1313:1314:1345:1359:1437:1515:1516:1518:1534:1539:1593:1594:1711:1730:1747:1777:1792:2393:2553:2559:2562:3138:3139:3140:3141:3142:3352:3622:3865:3871:3872:3874:4250:5007:6261:6742:7875:10004:10400:10848:10967:11232:11658:11914:12296:12517:12519:12663:12740:13069:13311:13357:14659:21080:30012:30054:30090:30091,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:none,Custom_rules:0:0:0,LFtime:2,LUA_SUMMARY:none
X-HE-Tag: month04_87550e300240e
X-Filterd-Recvd-Size: 2114
Date: Tue, 24 Nov 2015 15:45:28 -0500
From: Steven Rostedt <rostedt@goodmis.org>
To: Michal Hocko <mhocko@kernel.org>
Cc: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@kernel.org>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>, Vivek Goyal <vgoyal@redhat.com>,
        Baoquan He <bhe@redhat.com>, linux-doc@vger.kernel.org, x86@kernel.org,
        kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Subject: Re: [V5 PATCH 1/4] panic/x86: Fix re-entrance problem due to panic
 on NMI
Message-ID: <20151124154528.45203352@gandalf.local.home>
In-Reply-To: <20151124202712.GA23063@dhcp22.suse.cz>
References: <20151120093641.4285.97253.stgit@softrs>
	<20151120093644.4285.9349.stgit@softrs>
	<20151124150510.GA6100@home.goodmis.org>
	<20151124202712.GA23063@dhcp22.suse.cz>
X-Mailer: Claws Mail 3.13.0 (GTK+ 2.24.28; x86_64-pc-linux-gnu)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 839
Lines: 28

On Tue, 24 Nov 2015 21:27:13 +0100
Michal Hocko <mhocko@kernel.org> wrote:


> > What happens if:
> > 
> > 	CPU 0:				CPU 1:
> > 	------				------
> > 	nmi_panic();
> > 
> > 					nmi_panic();
> > 					<external nmi>
> > 					nmi_panic();  
> 
> I thought that nmi_panic is called only from the nmi context. If so how
> can we get a nested NMI like that?

Nevermind. I was thinking the external NMI could nest, but I'm guessing
it cant. Anyway, the patches later on modify this code which checks for
something other than != this_cpu, which makes this issue mute even if
it could nest.

-- Steve
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/