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From: "Dan Williams" <dan.j.williams@gmail.com>
To: "Neil Brown" <neilb@suse.de>
Cc: "Chuck Ebbert" <cebbert@redhat.com>,
	"Justin Piszcz" <jpiszcz@lucidpixels.com>,
	linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org,
	xfs@oss.sgi.com
Subject: Re: Kernel 2.6.19.2 New RAID 5 Bug (oops when writing Samba -> RAID5)
Date: Mon, 22 Jan 2007 18:44:11 -0700	[thread overview]
Message-ID: <e9c3a7c20701221744i7f0de470r4c8183dd3bcd20b5@mail.gmail.com> (raw)
In-Reply-To: <17845.13256.284461.992275@notabene.brown>

On 1/22/07, Neil Brown <neilb@suse.de> wrote:
> On Monday January 22, cebbert@redhat.com wrote:
> > Justin Piszcz wrote:
> > > My .config is attached, please let me know if any other information is
> > > needed and please CC (lkml) as I am not on the list, thanks!
> > >
> > > Running Kernel 2.6.19.2 on a MD RAID5 volume.  Copying files over Samba to
> > > the RAID5 running XFS.
> > >
> > > Any idea what happened here?
> ....
> > >
> > Without digging too deeply, I'd say you've hit the same bug Sami Farin
> > and others
> > have reported starting with 2.6.19: pages mapped with kmap_atomic()
> > become unmapped
> > during memcpy() or similar operations.  Try disabling preempt -- that
> > seems to be the
> > common factor.
>
> That is exactly the conclusion I had just come to (a kmap_atomic page
> must be being unmapped during memcpy).  I wasn't aware that others had
> reported it - thanks for that.
>
> Turning off CONFIG_PREEMPT certainly seems like a good idea.
>
Coming from an ARM background I am not yet versed in the inner
workings of kmap_atomic, but if you have time for a question I am
curious as to why spin_lock(&sh->lock)  is not sufficient pre-emption
protection for copy_data() in this case?

> NeilBrown

Regards,
Dan

  reply	other threads:[~2007-01-23  1:44 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-01-20 12:23 Justin Piszcz
2007-01-20 12:46 ` Justin Piszcz
2007-01-22 21:01 ` Chuck Ebbert
2007-01-22 21:59   ` Neil Brown
2007-01-23  1:44     ` Dan Williams [this message]
2007-01-23  2:06       ` Neil Brown
2007-01-23 10:56     ` Justin Piszcz
2007-01-23 11:08       ` Michael Tokarev
2007-01-23 11:59         ` Justin Piszcz
2007-01-23 12:48           ` Michael Tokarev
2007-01-23 13:46             ` Justin Piszcz
2007-01-24 23:37   ` Justin Piszcz
2007-01-26  9:25     ` Andrew Morton
2007-01-26  9:37       ` Justin Piszcz
2007-01-26 12:31       ` Justin Piszcz

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