From: ebiederm@xmission.com (Eric W. Biederman)
To: "Américo Wang" <xiyou.wangcong@gmail.com>
Cc: Vivek Goyal <vgoyal@redhat.com>,
kosaki.motohiro@jp.fujitsu.com,
linux kernel mailing list <linux-kernel@vger.kernel.org>,
Jarod Wilson <jwilson@redhat.com>
Subject: Re: Query about kdump_msg hook into crash_kexec()
Date: Mon, 31 Jan 2011 23:33:15 -0800 [thread overview]
Message-ID: <m1hbcous3o.fsf@fess.ebiederm.org> (raw)
In-Reply-To: <20110201071933.GA21239@cr0.nay.redhat.com> ("Américo Wang"'s message of "Tue, 1 Feb 2011 15:19:50 +0800")
Américo Wang <xiyou.wangcong@gmail.com> 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
next prev parent reply other threads:[~2011-02-01 7:33 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-31 22:59 Query about kdump_msg hook into crash_kexec() Vivek Goyal
2011-02-01 7:19 ` Américo Wang
2011-02-01 7:33 ` Eric W. Biederman [this message]
2011-02-01 7:38 ` Américo Wang
2011-02-01 8:13 ` [Patch] kexec: remove KMSG_DUMP_KEXEC (was Re: Query about kdump_msg hook into crash_kexec()) Américo Wang
2011-02-01 15:28 ` Vivek Goyal
2011-02-01 16:06 ` Jarod Wilson
2011-02-03 0:59 ` KOSAKI Motohiro
2011-02-03 2:07 ` Vivek Goyal
2011-02-03 4:53 ` KOSAKI Motohiro
2011-05-26 20:10 ` Andrew Morton
2011-05-28 1:43 ` Eric W. Biederman
2011-05-30 7:30 ` Américo Wang
2011-05-30 5:13 ` KOSAKI Motohiro
2011-05-31 21:51 ` Vivek Goyal
2011-06-09 11:00 ` KOSAKI Motohiro
2011-06-14 22:13 ` Vivek Goyal
2011-05-31 20:58 ` Seiji Aguchi
2011-05-31 21:37 ` Vivek Goyal
2011-05-31 22:24 ` Seiji Aguchi
2011-06-02 3:26 ` Eric W. Biederman
2011-06-08 0:00 ` Andrew Morton
2011-06-09 11:15 ` KOSAKI Motohiro
2011-02-03 0:55 ` Query about kdump_msg hook into crash_kexec() KOSAKI Motohiro
2011-02-03 2:05 ` Vivek Goyal
2011-02-03 4:52 ` KOSAKI Motohiro
2011-02-03 5:20 ` KOSAKI Motohiro
2011-02-04 15:00 ` Vivek Goyal
2011-03-08 1:31 ` KOSAKI Motohiro
2011-02-04 14:58 ` Vivek Goyal
2011-02-03 18:38 ` Seiji Aguchi
2011-02-03 21:13 ` Eric W. Biederman
2011-02-03 22:08 ` Seiji Aguchi
2011-02-04 2:24 ` Américo Wang
2011-02-04 2:50 ` Vivek Goyal
2011-02-04 3:28 ` Américo Wang
2011-02-04 6:40 ` KOSAKI Motohiro
2011-02-08 16:46 ` Vivek Goyal
2011-02-08 17:35 ` Eric W. Biederman
2011-02-08 19:27 ` Vivek Goyal
2011-02-08 19:58 ` Eric W. Biederman
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