From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755858AbbESMy7 (ORCPT ); Tue, 19 May 2015 08:54:59 -0400 Received: from cantor2.suse.de ([195.135.220.15]:38053 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755467AbbESMy5 (ORCPT ); Tue, 19 May 2015 08:54:57 -0400 Date: Tue, 19 May 2015 14:57:46 +0200 From: Petr Mladek To: Wang Long Cc: rostedt@goodmis.org, jkosina@suse.cz, gregkh@linuxfoundation.org, stable@vger.kernel.org, peifeiyue@huawei.com, linux-kernel@vger.kernel.org, paulmck@linux.vnet.ibm.com, dzickus@redhat.com, x86@kernel.org, morgan.wang@huawei.com, sasha.levin@oracle.com Subject: Re: [PATCH v2 00/17] [request for stable 3.10 inclusion] x86/nmi: Print all cpu stacks from NMI safely Message-ID: <20150519124754.GA12395@pathway.suse.cz> References: <1432026542-123571-1-git-send-email-long.wanglong@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1432026542-123571-1-git-send-email-long.wanglong@huawei.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 2015-05-19 09:08:45, Wang Long wrote: > This is my backport patch series to Fix the problem(backport to 3.10): > " > When trigger_all_cpu_backtrace() is called on x86, it will trigger an > NMI on each CPU and call show_regs(). But this can lead to a hard lock > up if the NMI comes in on another printk(). > " > The solution is described in commit "a9edc88093287183ac934be44f295f183b2c62dd": > when the NMI triggers, it switches the printk routine for that CPU to call > a NMI safe printk function that records the printk in a per_cpu seq_buf > descriptor. After all NMIs have finished recording its data, the trace_ > seqs are printed in a safe context. > > The solution use "switch printk routine" and "seq_buf" infrastructures, but the > 3.10 stable have no both of them. > > The patch 1-13 backport the "seq_buf" infrastructures. in detail, patch 1, 2 > and 6 only backport "seq_buf" related code. > > The patch 14-15 backport the "switch printk routine". > > The patch 16-17 is the patch to print all cpu stacks from NMI safely > > as discussed in https://lkml.org/lkml/2015/5/13/497, in 3.10 stable, this is > the only way to solve the problem and the backport code is a bit more. > > v1 -> v2: > * fix the indent error. > * rebase on 3.10.79 > > Any thoughts? Please, wait with the integration. I am testing it with a storm of sysrq requests: $> while true ; do echo l >/proc/sysrq-trigger ; done with iptables enabled: $> iptables -A INPUT -j LOG --log-prefix "incomming packet:" and storm of pings from other machine: $> ping -f The machine somehow freezes. It does not make sense. I am trying to investigate. Best Regards, Petr