From: ebiederm@xmission.com (Eric W. Biederman)
To: Yinghai Lu <yinghai@kernel.org>
Cc: nhorman@redhat.com, nhorman@tuxdriver.com,
Bernhard Walle <bernhard@bwalle.de>,
Joerg Roedel <joerg.roedel@amd.com>,
Joerg Roedel <joro@8bytes.org>,
kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
Chris Wright <chrisw@sous-sol.org>,
hbabu@us.ibm.com, iommu@lists.linux-foundation.org,
Vivek Goyal <vgoyal@redhat.com>
Subject: Re: [PATCH 3/4] Revert "x86: disable IOMMUs on kernel crash"
Date: Tue, 06 Apr 2010 15:10:14 -0700 [thread overview]
Message-ID: <m1y6h0qlkp.fsf@fess.ebiederm.org> (raw)
In-Reply-To: <z2w86802c441004061445q5a05832fmaece2723436f803f@mail.gmail.com> (Yinghai Lu's message of "Tue\, 6 Apr 2010 14\:45\:51 -0700")
Yinghai Lu <yinghai@kernel.org> writes:
> not sure if it is related:
I don't think it is.
> for crashing kernel, it could do early_memtest to check if some device
> are still do dma operation.
Devices doing DMA in general are not a problem in the kdump kernel
because we are using an area of memory that has been reserved since
the beginning of time and no DMA's should be targeting it. The challenge
is how to regain control of the IOMMU.
> When I use kexec to start second kernel, if enable the early_memtest
> in second kernel, it will find some pages RAM are BAD,
> and it will mark them and not use them. memtest=1 should be good enough.
> Fresh restart will not report there is any BAD ram in the same system.
I assume you are not talking kdump here.
On-going DMA in the case of kexec indicates some device driver isn't shutting
itself down when it's shutdown method is called.
Odds are it is a network controller that doesn't stop DMA when it is brought
down or it is, possibly a really weird disk driver.
If you are seeing this with the kdump kernel this may indeed indicate an
IOMMU reinitialization problem.
Eric
_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec
next prev parent reply other threads:[~2010-04-06 22:10 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-03 1:27 [PATCH 0/4] AMD IOMMU kdump fix plus cleanups (v2) Chris Wright
2010-04-03 1:27 ` [PATCH 1/4] x86/amd-iommu: enable iommu before attaching devices Chris Wright
2010-04-03 1:27 ` [PATCH 2/4] x86/amd-iommu: warn when issuing command to uninitialized cmd buffer Chris Wright
2010-04-03 1:27 ` [PATCH 3/4] Revert "x86: disable IOMMUs on kernel crash" Chris Wright
2010-04-03 17:22 ` Joerg Roedel
2010-04-03 17:44 ` Eric W. Biederman
2010-04-04 8:44 ` Joerg Roedel
2010-04-04 9:16 ` Eric W. Biederman
2010-04-04 9:19 ` Eric W. Biederman
2010-04-03 17:41 ` Joerg Roedel
2010-04-03 17:49 ` Eric W. Biederman
2010-04-03 19:13 ` Joerg Roedel
2010-04-03 19:41 ` Eric W. Biederman
2010-04-04 7:24 ` Bernhard Walle
2010-04-04 7:51 ` Eric W. Biederman
2010-04-04 8:53 ` Joerg Roedel
2010-04-04 9:44 ` Eric W. Biederman
2010-04-04 10:01 ` Joerg Roedel
2010-04-06 17:42 ` Chris Wright
2010-04-06 17:51 ` Joerg Roedel
2010-04-06 20:39 ` Vivek Goyal
2010-04-06 21:13 ` Vivek Goyal
2010-04-06 21:45 ` Yinghai Lu
2010-04-06 22:10 ` Eric W. Biederman [this message]
2010-04-04 11:54 ` David Woodhouse
2010-04-03 1:27 ` [PATCH 4/4] x86/amd-iommu: use for_each_pci_dev Chris Wright
2010-04-07 10:05 ` [PATCH 0/4] AMD IOMMU kdump fix plus cleanups (v2) Joerg Roedel
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=m1y6h0qlkp.fsf@fess.ebiederm.org \
--to=ebiederm@xmission.com \
--cc=bernhard@bwalle.de \
--cc=chrisw@sous-sol.org \
--cc=hbabu@us.ibm.com \
--cc=iommu@lists.linux-foundation.org \
--cc=joerg.roedel@amd.com \
--cc=joro@8bytes.org \
--cc=kexec@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=nhorman@redhat.com \
--cc=nhorman@tuxdriver.com \
--cc=vgoyal@redhat.com \
--cc=yinghai@kernel.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox