From: Mahesh Jagannath Salgaonkar <mahesh@linux.vnet.ibm.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: linuxppc-dev@ozlabs.org, akpm@linux-foundation.org,
kexec@lists.infradead.org, Anton Blanchard <anton@samba.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] kdump: Allow shrinking of kdump region to be overridden
Date: Wed, 09 Mar 2011 12:02:06 +0530 [thread overview]
Message-ID: <4D771EE6.5050404@linux.vnet.ibm.com> (raw)
In-Reply-To: <m139u37cii.fsf@fess.ebiederm.org>
On 08/25/2010 06:07 AM, Eric W. Biederman wrote:
> Anton Blanchard <anton@samba.org> writes:
>
>> On ppc64 the crashkernel region almost always overlaps an area of firmware.
>> This works fine except when using the sysfs interface to reduce the kdump
>> region. If we free the firmware area we are guaranteed to crash.
>
> That is ppc64 bug. firmware should not be in the reserved region. Any
> random kernel like thing can be put in to that region at any valid
> address and the fact that shrinking the region frees your firmware means
> that using that region could also stomp your firmware (which I assume
> would be a bad thing).
The issue only happens while shrinking the region using sysfs interface.
We already have checks in kexec for not to stomp over on the firmware
overlap area while loading capture kernel. Currently we do a top-down
allocation for the firmware region which means it sits at the top of the
RMO, right in the middle of the crashdump region. We can not move the
crashkernel region beyond firmware region because kernel needs its some
of memory in RMO region.
>
> So please fix the ppc64 reservation.
>
> Eric
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev
_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec
WARNING: multiple messages have this Message-ID (diff)
From: Mahesh Jagannath Salgaonkar <mahesh@linux.vnet.ibm.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: linuxppc-dev@ozlabs.org, akpm@linux-foundation.org,
kexec@lists.infradead.org, Anton Blanchard <anton@samba.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] kdump: Allow shrinking of kdump region to be overridden
Date: Wed, 09 Mar 2011 12:02:06 +0530 [thread overview]
Message-ID: <4D771EE6.5050404@linux.vnet.ibm.com> (raw)
In-Reply-To: <m139u37cii.fsf@fess.ebiederm.org>
On 08/25/2010 06:07 AM, Eric W. Biederman wrote:
> Anton Blanchard <anton@samba.org> writes:
>
>> On ppc64 the crashkernel region almost always overlaps an area of firmware.
>> This works fine except when using the sysfs interface to reduce the kdump
>> region. If we free the firmware area we are guaranteed to crash.
>
> That is ppc64 bug. firmware should not be in the reserved region. Any
> random kernel like thing can be put in to that region at any valid
> address and the fact that shrinking the region frees your firmware means
> that using that region could also stomp your firmware (which I assume
> would be a bad thing).
The issue only happens while shrinking the region using sysfs interface.
We already have checks in kexec for not to stomp over on the firmware
overlap area while loading capture kernel. Currently we do a top-down
allocation for the firmware region which means it sits at the top of the
RMO, right in the middle of the crashdump region. We can not move the
crashkernel region beyond firmware region because kernel needs its some
of memory in RMO region.
>
> So please fix the ppc64 reservation.
>
> Eric
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev
WARNING: multiple messages have this Message-ID (diff)
From: Mahesh Jagannath Salgaonkar <mahesh@linux.vnet.ibm.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Anton Blanchard <anton@samba.org>,
akpm@linux-foundation.org, kexec@lists.infradead.org,
linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org
Subject: Re: [PATCH 1/2] kdump: Allow shrinking of kdump region to be overridden
Date: Wed, 09 Mar 2011 12:02:06 +0530 [thread overview]
Message-ID: <4D771EE6.5050404@linux.vnet.ibm.com> (raw)
In-Reply-To: <m139u37cii.fsf@fess.ebiederm.org>
On 08/25/2010 06:07 AM, Eric W. Biederman wrote:
> Anton Blanchard <anton@samba.org> writes:
>
>> On ppc64 the crashkernel region almost always overlaps an area of firmware.
>> This works fine except when using the sysfs interface to reduce the kdump
>> region. If we free the firmware area we are guaranteed to crash.
>
> That is ppc64 bug. firmware should not be in the reserved region. Any
> random kernel like thing can be put in to that region at any valid
> address and the fact that shrinking the region frees your firmware means
> that using that region could also stomp your firmware (which I assume
> would be a bad thing).
The issue only happens while shrinking the region using sysfs interface.
We already have checks in kexec for not to stomp over on the firmware
overlap area while loading capture kernel. Currently we do a top-down
allocation for the firmware region which means it sits at the top of the
RMO, right in the middle of the crashdump region. We can not move the
crashkernel region beyond firmware region because kernel needs its some
of memory in RMO region.
>
> So please fix the ppc64 reservation.
>
> Eric
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev
next prev parent reply other threads:[~2011-03-09 6:32 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-25 0:22 [PATCH 1/2] kdump: Allow shrinking of kdump region to be overridden Anton Blanchard
2010-08-25 0:22 ` Anton Blanchard
2010-08-25 0:22 ` Anton Blanchard
2010-08-25 0:23 ` [PATCH 2/2] powerpc: kdump: Override crash_free_reserved_phys_range to avoid freeing RTAS Anton Blanchard
2010-08-25 0:23 ` Anton Blanchard
2010-08-25 0:23 ` Anton Blanchard
2010-08-25 0:37 ` [PATCH 1/2] kdump: Allow shrinking of kdump region to be overridden Eric W. Biederman
2010-08-25 0:37 ` Eric W. Biederman
2010-08-25 0:37 ` Eric W. Biederman
2011-03-09 6:32 ` Mahesh Jagannath Salgaonkar [this message]
2011-03-09 6:32 ` Mahesh Jagannath Salgaonkar
2011-03-09 6:32 ` Mahesh Jagannath Salgaonkar
2011-03-09 12:20 ` Américo Wang
2011-03-09 12:20 ` Américo Wang
2011-03-09 12:20 ` Américo Wang
2011-03-09 12:46 ` Anton Blanchard
2011-03-09 12:46 ` Anton Blanchard
2011-03-09 12:46 ` Anton Blanchard
2011-03-09 14:21 ` Américo Wang
2011-03-09 14:21 ` Américo Wang
2011-03-09 14:21 ` Américo Wang
2011-03-14 18:13 ` Mahesh J Salgaonkar
2011-03-14 18:13 ` Mahesh J Salgaonkar
2011-03-14 18:13 ` Mahesh J Salgaonkar
2011-03-15 7:52 ` Américo Wang
2011-03-15 7:52 ` Américo Wang
2011-03-15 7:52 ` Américo Wang
2011-03-15 16:52 ` Mahesh J Salgaonkar
2011-03-15 16:52 ` Mahesh J Salgaonkar
2011-03-15 16:52 ` Mahesh J Salgaonkar
2011-03-21 3:10 ` WANG Cong
2011-03-21 3:10 ` WANG Cong
2011-03-24 4:33 ` Benjamin Herrenschmidt
2011-03-24 4:33 ` Benjamin Herrenschmidt
2011-03-24 4:33 ` Benjamin Herrenschmidt
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=4D771EE6.5050404@linux.vnet.ibm.com \
--to=mahesh@linux.vnet.ibm.com \
--cc=akpm@linux-foundation.org \
--cc=anton@samba.org \
--cc=ebiederm@xmission.com \
--cc=kexec@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@ozlabs.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.