From: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
To: Shuah Khan <shuah.khan-VXdhtT5mjnY@public.gmane.org>
Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
stable <stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
shuahkhan-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
Subject: Re: IO_PAGE_FAULTs on unity mapped regions during amd_iommu_init() in Linux 3.4
Date: Tue, 5 Feb 2013 14:31:05 +0100 [thread overview]
Message-ID: <20130205133104.GC2532@8bytes.org> (raw)
In-Reply-To: <1359743519.2759.38.camel@lorien2>
Hi Shuah,
On Fri, Feb 01, 2013 at 11:31:59AM -0700, Shuah Khan wrote:
> Yes, 3.7 has the same window of opportunity for this race condition,
> however I couldn't figure out why it doesn't happen on 3.7. On 3.7 the
> window between amd_iommu_init_hardware() and amd_iommu_init_dma_ops()
> might actually be wider than the window in 3.4.
I think this is highly timing related. IOMMU initialization may have
been moved by a few milliseconds between the kernel versions which might
cause the warnings to appear or disappear. I don't think it has much
value to dive deeper into the differences between the initialization
sequences.
As somethimes with such issues there is a simple and a more complex fix
for that. I'll try to come up with a simple fix for the next merge
window and implement the clean and more complex one for the next one.
Joerg
next prev parent reply other threads:[~2013-02-05 13:31 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-31 18:33 IO_PAGE_FAULTs on unity mapped regions during amd_iommu_init() in Linux 3.4 Shuah Khan
2013-02-01 13:00 ` Joerg Roedel
2013-02-01 18:31 ` Shuah Khan
2013-02-05 13:31 ` Joerg Roedel [this message]
[not found] ` <20130205133104.GC2532-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2013-02-05 13:57 ` Shuah Khan
2013-02-06 12:12 ` Joerg Roedel
2013-02-07 2:40 ` Shuah Khan
2013-02-11 19:49 ` Greg KH
[not found] ` <20130211194901.GA18115-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
2013-02-11 20:17 ` Shuah Khan
2013-02-11 20:57 ` Shuah Khan
2013-02-11 22:18 ` Joerg Roedel
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