linux-kernel - Re: bus errors on nfs writes in latest git

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Date:	Mon, 6 Apr 2009 17:37:03 +0200 (CEST)
From:	Geert Uytterhoeven <Geert.Uytterhoeven@...ycom.com>
To:	"J. Bruce Fields" <bfields@...ldses.org>
cc:	Trond Myklebust <Trond.Myklebust@...app.com>,
	linux-nfs@...r.kernel.org, Nick Piggin <npiggin@...e.de>,
	linux-kernel@...r.kernel.org
Subject: Re: bus errors on nfs writes in latest git

On Sun, 5 Apr 2009, J. Bruce Fields wrote:
> On Sat, Apr 04, 2009 at 12:27:50PM -0400, Trond Myklebust wrote:
> > On Sat, 2009-04-04 at 12:19 -0400, Trond Myklebust wrote:
> > > On Sat, 2009-04-04 at 12:14 -0400, J. Bruce Fields wrote:
> > > > My regular connecthon tests are reporting bus errors on the "write/read
> > > > 30 MB file" on recent upstream kernels.  I'm travelling and haven't had
> > > > a chance to do anything beyond kick off a dumb git-bisect, which pointed
> > > > the blame at the following commit.  Any ideas?
> > 
> > The following patch should fix it.
> 
> Thanks--confirmed.  For what it's worth:
> 
> 	Tested-by: J. Bruce Fields <bfields@...i.umich.edu>

JFYI, I was also seeing bus errors and read() returning EFAULT with current
mainline on both PS3 (ppc64) and Sequoia (ppc32). So far I only saw it
happening doing:
  - apt-get update
  - apt-get upgrade
  - apt-get install

I tried bisecting it, but unfortunately it was not 100% reproducible.
So far the oldest version where I saw it fail was 2.6.29-07100-g833bb30.
It _looks_ like 2.6.29-06619-ge5824c9 is OK, but I'm not 100% sure.

At first I didn't think of NFS (I'm indeed using nfsroot), but when searching
for `bus error' I noticed this thread.

Your patch seems to fix it (I added a printk so I would notice when the bad
case got triggered), and the commit that introduced the problem lies within
the works/fails range I discovered, so

Tested-by: Geert Uytterhoeven <Geert.Uytterhoeven@...ycom.com>

Thanks!

With kind regards,

Geert Uytterhoeven
Software Architect

Sony Techsoft Centre Europe
The Corporate Village · Da Vincilaan 7-D1 · B-1935 Zaventem · Belgium

Phone:    +32 (0)2 700 8453
Fax:      +32 (0)2 700 8622
E-mail:   Geert.Uytterhoeven@...ycom.com
Internet: http://www.sony-europe.com/

A division of Sony Europe (Belgium) N.V.
VAT BE 0413.825.160 · RPR Brussels
Fortis · BIC GEBABEBB · IBAN BE41293037680010

> > 
> > Cheers
> >  Trond
> > ---------------------------------------------------------------
> > >From b7a178f4fab331821b8cff384e1954e62aa63e52 Mon Sep 17 00:00:00 2001
> > From: Trond Myklebust <Trond.Myklebust@...app.com>
> > Date: Sat, 4 Apr 2009 12:22:57 -0400
> > Subject: [PATCH] NFS: Fix the return value in nfs_page_mkwrite()
> > 
> > Commit c2ec175c39f62949438354f603f4aa170846aabb (mm: page_mkwrite change
> > prototype to match fault) exposed a bug in the NFS implementation of
> > page_mkwrite. We should be returning 0 on success...
> > 
> > Signed-off-by: Trond Myklebust <Trond.Myklebust@...app.com>
> > ---
> >  fs/nfs/file.c |    2 --
> >  1 files changed, 0 insertions(+), 2 deletions(-)
> > 
> > diff --git a/fs/nfs/file.c b/fs/nfs/file.c
> > index 3523b89..5a97bcf 100644
> > --- a/fs/nfs/file.c
> > +++ b/fs/nfs/file.c
> > @@ -516,8 +516,6 @@ static int nfs_vm_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
> >  		goto out_unlock;
> >  
> >  	ret = nfs_updatepage(filp, page, 0, pagelen);
> > -	if (ret == 0)
> > -		ret = pagelen;
> >  out_unlock:
> >  	unlock_page(page);
> >  	if (ret)
> > -- 
> > 1.6.0.4
> > 
> > 
> > -- 
> > Trond Myklebust
> > Linux NFS client maintainer
> > 
> > NetApp
> > Trond.Myklebust@...app.com
> > www.netapp.com
> --
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> 

With kind regards,

Geert Uytterhoeven
Software Architect

Sony Techsoft Centre Europe
The Corporate Village · Da Vincilaan 7-D1 · B-1935 Zaventem · Belgium

Phone:    +32 (0)2 700 8453
Fax:      +32 (0)2 700 8622
E-mail:   Geert.Uytterhoeven@...ycom.com
Internet: http://www.sony-europe.com/

A division of Sony Europe (Belgium) N.V.
VAT BE 0413.825.160 · RPR Brussels
Fortis · BIC GEBABEBB · IBAN BE41293037680010
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