From: ebiederm@xmission.com (Eric W. Biederman)
To: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Borislav Petkov <bp@alien8.de>, Andi Kleen <andi@firstfloor.org>,
"rdunlap@xenotime.net" <rdunlap@xenotime.net>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"mingo@redhat.com" <mingo@redhat.com>,
"hpa@zytor.com" <hpa@zytor.com>,
"x86@kernel.org" <x86@kernel.org>,
"akpm@linuxfoundation.org" <akpm@linuxfoundation.org>,
"eugeneteo@kernel.org" <eugeneteo@kernel.org>,
"kees.cook@canonical.com" <kees.cook@canonical.com>,
"drosenberg@vsecurity.com" <drosenberg@vsecurity.com>,
"ying.huang@intel.com" <ying.huang@intel.com>,
"len.brown@intel.com" <len.brown@intel.com>,
"seto.hidetoshi@jp.fujitsu.com" <seto.hidetoshi@jp.fujitsu.com>,
"paulmck@linux.vnet.ibm.com" <paulmck@linux.vnet.ibm.com>,
"gregkh@suse.de" <gregkh@suse.de>,
"davem@davemloft.net" <davem@davemloft.net>,
"hadi@cyberus.ca" <hadi@cyberus.ca>,
"hawk@comx.dk" <hawk@comx.dk>,
"opurdila@ixiacom.com" <opurdila@ixiacom.com>,
"hidave.darkstar@gmail.com" <hidave.darkstar@gmail.com>,
"dzickus@redhat.com" <dzickus@redhat.com>,
"eric.dumazet@gmail.com" <eric.dumazet@gmail.com>,
"ext-andriy.shevchenko@nokia.com"
<ext-andriy.shevchenko@nokia.com>,
"tj@kernel.org" <tj@kernel.org>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kexec@lists.infradead.org" <kexec@lists.infradead.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"dle-develop@lists.sourceforge.net"
<dle-develop@lists.sourceforge.net>,
Satoru Moriya <satoru.moriya@hds.com>
Subject: Re: [RFC][PATCH] Add a sysctl option controlling kexec when MCE occurred
Date: Sat, 25 Dec 2010 09:19:54 -0800 [thread overview]
Message-ID: <m1oc89ixc5.fsf@fess.ebiederm.org> (raw)
In-Reply-To: <5C4C569E8A4B9B42A84A977CF070A35B2C132F6CFA@USINDEVS01.corp.hds.com> (Seiji Aguchi's message of "Sat, 25 Dec 2010 09:56:50 -0500")
Seiji Aguchi <seiji.aguchi@hds.com> writes:
> Hi,
>
> Thank you for giving your comments.
>
>>So what is the problem you are trying to avoid, and why can't we do
>>something in the kernels initialization path to avoid initializing
>>when there is a problem?
>
> Kdump gets a dump disk identifier based on information from memory.
>
> So, kdump may receive wrong identifier when it starts after MCE
> occurred, because MCE is reported by memory, cache, and TLB errors
>
> In the worst case, kdump will overwrite user data if it recognizes a
> disk saving user data as a dump disk.
Absurdly unlikely there is a sha256 checksum verified over the
kdump kernel before it starts booting. If you have very broken
memory it is possible, but absurdly unlikely that the machine will
even boot if you are having enough uncorrectable memory errors
an hour to get past the sha256 checksum and then be corruppt.
> Kdump shouldn't write any data to disk when information from
> hardware is incredible because saving user data is always first
> priority.
Which is what is already implemented.
It looks to me like you are jumping at shadows, and adding
complexity to the kernel with no gain, and significant cost.
Eric
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2010-12-25 17:20 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-22 23:35 Seiji Aguchi
2010-12-23 0:29 ` Greg KH
2010-12-23 7:43 ` Andi Kleen
2010-12-23 9:18 ` Borislav Petkov
2010-12-23 17:31 ` Seiji Aguchi
2010-12-23 19:56 ` Eric W. Biederman
2010-12-25 14:56 ` Seiji Aguchi
2010-12-25 17:19 ` Eric W. Biederman [this message]
2010-12-25 18:33 ` H. Peter Anvin
2010-12-25 21:40 ` Eric W. Biederman
2010-12-27 1:56 ` Hidetoshi Seto
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=m1oc89ixc5.fsf@fess.ebiederm.org \
--to=ebiederm@xmission.com \
--cc=akpm@linuxfoundation.org \
--cc=andi@firstfloor.org \
--cc=bp@alien8.de \
--cc=davem@davemloft.net \
--cc=dle-develop@lists.sourceforge.net \
--cc=drosenberg@vsecurity.com \
--cc=dzickus@redhat.com \
--cc=eric.dumazet@gmail.com \
--cc=eugeneteo@kernel.org \
--cc=ext-andriy.shevchenko@nokia.com \
--cc=gregkh@suse.de \
--cc=hadi@cyberus.ca \
--cc=hawk@comx.dk \
--cc=hidave.darkstar@gmail.com \
--cc=hpa@zytor.com \
--cc=kees.cook@canonical.com \
--cc=kexec@lists.infradead.org \
--cc=len.brown@intel.com \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mingo@redhat.com \
--cc=opurdila@ixiacom.com \
--cc=paulmck@linux.vnet.ibm.com \
--cc=rdunlap@xenotime.net \
--cc=satoru.moriya@hds.com \
--cc=seiji.aguchi@hds.com \
--cc=seto.hidetoshi@jp.fujitsu.com \
--cc=tglx@linutronix.de \
--cc=tj@kernel.org \
--cc=x86@kernel.org \
--cc=ying.huang@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox