From: Bjorn Helgaas <helgaas@kernel.org>
To: Christian Melki <christian.melki@t2data.com>
Cc: linux-pci@vger.kernel.org,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Joerg Roedel <joro@8bytes.org>,
iommu@lists.linux-foundation.org
Subject: Re: Fwd: SWIOTLB on 32-bit PAE.
Date: Sat, 3 Oct 2015 09:36:30 -0500 [thread overview]
Message-ID: <20151003143630.GB17684@localhost> (raw)
In-Reply-To: <560E92A0.9030707@t2data.com>
[+cc Konrad, Joerg, iommu list]
On Fri, Oct 02, 2015 at 04:20:16PM +0200, Christian Melki wrote:
> I discovered a strange error on my machine. 32-bit PAE 4.2.0 without
> IOMMU code (yeah, I know).
> When writing to an ext4 filesystem on a USB disk my kernel would hang
> and not return control to userspace. It would spew kernel messages to
> syslog as fast as it could without giving userspace any time, ie "hang"
> as far as a user sees it. The device itself is ok and the filesystem is
> clean.
> I get messages like this, millions of them.
>
> Oct 2 14:33:06 voodoochild kernel: [ 223.287447] nommu_map_sg:
> overflow 25dcac000+1024 of device mask ffffffff
> Oct 2 14:33:06 voodoochild kernel: [ 223.287448] nommu_map_sg:
> overflow 25dcac000+1024 of device mask ffffffff
> Oct 2 14:33:06 voodoochild kernel: [ 223.287449] nommu_map_sg:
> overflow 25dcac000+1024 of device mask ffffffff
>
> I disovered that SWIOTLB was not on. It is only provided for 64-bit
> machines where it is default. On 32-bit SWIOTLB seems disabled
> unless you are running with some IOMMU/AGPGART code.
>
> But what about 32-bit PAE? Would that not qualify for SWIOTLB without IOMMU?
>
> I am a novice in this area. Maybe this is a Kconfig "bug" for us
> that like to hang ourselves with CONFIG_* rope? :) I'd like to think
> that SWIOTLB should be default for 32-bit PAE too?
>
> Best regards,
> Christian
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2015-10-03 14:36 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <560E9007.1000604@t2data.com>
2015-10-02 14:20 ` Fwd: SWIOTLB on 32-bit PAE Christian Melki
2015-10-03 14:36 ` Bjorn Helgaas [this message]
2015-10-03 18:00 ` Konrad Rzeszutek Wilk
2015-10-05 10:00 ` 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=20151003143630.GB17684@localhost \
--to=helgaas@kernel.org \
--cc=christian.melki@t2data.com \
--cc=iommu@lists.linux-foundation.org \
--cc=joro@8bytes.org \
--cc=konrad.wilk@oracle.com \
--cc=linux-pci@vger.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;
as well as URLs for NNTP newsgroup(s).