Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751941Ab1BAHdX (ORCPT ); Tue, 1 Feb 2011 02:33:23 -0500 Received: from out01.mta.xmission.com ([166.70.13.231]:45891 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751167Ab1BAHdV convert rfc822-to-8bit (ORCPT ); Tue, 1 Feb 2011 02:33:21 -0500 From: ebiederm@xmission.com (Eric W. Biederman) To: =?utf-8?Q?Am=C3=A9rico?= Wang Cc: Vivek Goyal , kosaki.motohiro@jp.fujitsu.com, linux kernel mailing list , Jarod Wilson References: <20110131225939.GH11974@redhat.com> <20110201071933.GA21239@cr0.nay.redhat.com> Date: Mon, 31 Jan 2011 23:33:15 -0800 In-Reply-To: <20110201071933.GA21239@cr0.nay.redhat.com> (=?utf-8?Q?=22Am?= =?utf-8?Q?=C3=A9rico?= Wang"'s message of "Tue, 1 Feb 2011 15:19:50 +0800") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT X-XM-SPF: eid=;;;mid=;;;hst=in01.mta.xmission.com;;;ip=98.207.157.188;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX19Xe3v2YMtr9eT/H6L0DXA9+B/aj1u8RZ0= X-SA-Exim-Connect-IP: 98.207.157.188 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -3.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa01 1397; Body=1 Fuz1=1 Fuz2=1] * 0.0 T_XMDrugObfuBody_08 obfuscated drug references * 0.4 UNTRUSTED_Relay Comes from a non-trusted relay X-Spam-DCC: XMission; sa01 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: =?ISO-8859-1?Q?;Am=c3=a9rico Wang ?= X-Spam-Relay-Country: Subject: Re: Query about kdump_msg hook into crash_kexec() X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Fri, 06 Aug 2010 16:31:04 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1335 Lines: 31 Américo Wang writes: > On Mon, Jan 31, 2011 at 05:59:39PM -0500, Vivek Goyal wrote: >> >>Anyway, if an image is loaded and we have setup to capture dump also >>why do we need to save kmsg with the help of an helper. I am assuming >>this is more of a debugging aid if we have no other way to capture the >>kernel log buffer. So if somebody has setup kdump to capture the >>vmcore, why to call another handler which tries to save part of the >>vmcore (kmsg) separately. >> > > Well, kmsg dumper is not only for panic/oops, it can also save kernel > messages when the system is reboot/halt. > > Yeah, it is true that vmcore contains log_buf, but I think the users > of ramoops/mtdoops are mainly those who don't have kdump configured > in their kernels, they are cheaper than kdump, but less powerful The issue is the inane call inside crash_kexec. It requires both a kexec kernel to be loaded and it requires you to be crashing. Given that when I audited the kmsg_dump handlers they really weren't safe in a crash dump scenario we should just remove it. Eric -- 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/