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=-7.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 0CE6AC433DF for ; Thu, 11 Jun 2020 07:58:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D4CD7204EA for ; Thu, 11 Jun 2020 07:58:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726805AbgFKH6X (ORCPT ); Thu, 11 Jun 2020 03:58:23 -0400 Received: from mx2.suse.de ([195.135.220.15]:52810 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726694AbgFKH6X (ORCPT ); Thu, 11 Jun 2020 03:58:23 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id D33BBACF9; Thu, 11 Jun 2020 07:58:23 +0000 (UTC) Date: Thu, 11 Jun 2020 09:58:18 +0200 From: Petr Mladek To: Daniel Thompson Cc: Sergey Senozhatsky , Sumit Garg , Jason Wessel , Douglas Anderson , kgdb-bugreport@lists.sourceforge.net, Linux Kernel Mailing List , Arnd Bergmann , Andrew Morton , Peter Zijlstra , Steven Rostedt , John Ogness Subject: Re: [PATCH] printk/kdb: Redirect printk messages into kdb in any context Message-ID: <20200611075818.GC6581@linux-b0ei> References: <1589273314-12060-1-git-send-email-sumit.garg@linaro.org> <20200512142533.ta4uejwmq5gchtlx@holly.lan> <20200514084230.GO17734@linux-b0ei> <20200515085021.GS17734@linux-b0ei> <20200515103308.GD42471@jagdpanzerIV.localdomain> <20200515163638.GI42471@jagdpanzerIV.localdomain> <20200610164140.tgzcn5oip2gzgmze@holly.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200610164140.tgzcn5oip2gzgmze@holly.lan> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 2020-06-10 17:41:40, Daniel Thompson wrote: > On Sat, May 16, 2020 at 01:36:38AM +0900, Sergey Senozhatsky wrote: > > On (20/05/15 17:32), Sumit Garg wrote: > > > > Can I please have some context what problem does this solve? > > > > > > You can find the problem description here [1] which leads to this fix. > > > > [..] > > > > > [1] https://lkml.org/lkml/2020/5/12/213 > > > > Thanks for the link. I'm slightly surprised it took so many years > > to notice the addition of printk_nmi/printk_safe :) > > Rather by coincidence (at least I think its a coincidence) the problem > has recently become much more obvious. > > 0d00449c7a28 ("x86: Replace ist_enter() with nmi_enter()") just brought > this to the surface by treating debug traps as NMIs. This means the CPU > that takes a breakpoint, and where almost all of the kdb printk() calls > take place, will now unconditionally have printk() interception enabled. Mea culpa. I have marked this patch as proceed by mistake. It has got enough acks and is ready for 5.8. I have just commited the patch into printk/linux.git, branch for-5.8-kdb-nmi. I am going to push it to Linus when it passes linux-next integration, hopefully tomorrow. Thanks a lot for poking me. Best Regards, Petr