Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755459AbYLSWgb (ORCPT ); Fri, 19 Dec 2008 17:36:31 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754446AbYLSWgO (ORCPT ); Fri, 19 Dec 2008 17:36:14 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:46564 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753604AbYLSWgN (ORCPT ); Fri, 19 Dec 2008 17:36:13 -0500 Date: Fri, 19 Dec 2008 23:35:58 +0100 From: Ingo Molnar To: Hiroshi Shimamoto Cc: Toshikazu Nakayama , linux-kernel@vger.kernel.org Subject: Re: [PATCH] printk: fix discarding message when recursion_bug Message-ID: <20081219223558.GC13409@elte.hu> References: <494BE687.2040700@ct.jp.nec.com> <20081219215347.GG2351@elte.hu> <494C1D20.9000008@ct.jp.nec.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <494C1D20.9000008@ct.jp.nec.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1449 Lines: 38 * Hiroshi Shimamoto wrote: > Ingo Molnar wrote: > > * Hiroshi Shimamoto wrote: > > > >> From: Hiroshi Shimamoto > >> > >> Impact: fix > >> > >> When recursion_bug is true, kernel discards original message because printk_buf > >> contains recursion_bug_msg with NULL terminator. The sizeof(recursion_bug_msg) > >> makes this, use strlen() to get correct length without NULL terminator. > >> > >> Reported-by: Toshikazu Nakayama > >> Signed-off-by: Hiroshi Shimamoto > >> --- > >> kernel/printk.c | 2 +- > >> 1 files changed, 1 insertions(+), 1 deletions(-) > > > > Good one - applied to tip/core/printk, thanks! > > > > Btw., i'm curious: in what situation was such recursion observed, and how > > did the kernel behave? You saw a truncated recursion message in dmesg - or > > was it worse? > > I'm not sure about the real situation. I've heard this issue was found > in printing messages in NMI handler, maybe with artificial kernel stuck. yeah, accidental NMI recursion back into printk could indeed cause the recursion message to pop up. Ingo -- 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/