Re: [PATCH v2]Btrfs: pwrite blocked when writing from the mmaped buffer of the same page

From: Piotr Szymaniak <szarpaj@grubelek.pl>
To: "Zhong, Xin" <xin.zhong@intel.com>
Cc: "Maria Wikström" <maria@ponstudios.se>,
	"Johannes Hirte" <johannes.hirte@fem.tu-ilmenau.de>,
	"linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>
Subject: Re: [PATCH v2]Btrfs: pwrite blocked when writing from the mmaped buffer of the same page
Date: Fri, 25 Feb 2011 00:35:23 +0100	[thread overview]
Message-ID: <20110224233523.GK26836@wloczykij> (raw)
In-Reply-To: <1865303E0DED764181A9D882DEF65FB686421B24FB@shsmsx502.ccr.corp.intel.com>

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On Mon, Feb 21, 2011 at 09:51:11AM +0800, Zhong, Xin wrote:
> The backtrace in your attachment looks like a known bug of 2.6.37 which have already been fixed in 2.6.38. I have no idea why latest btrfs still hang in your environment if there's no debug info...

Hi list.

I'm watching this list for a while because it seems, that I'm also
affected by this bug. In the archives I found someone with Gentoo system
with freezing `svn info' (thats why I joined). Well, seems that I have 
same issue here.

Attached latest _rc kernel sysrq+t output (first part when the `svn
info' freezed on libgcrypt, and second after ctrl+c that emerge).

Seems that my backtrace is small compared to Marias. I'm missing some
features in kernel to get larger backtraces?

Piotr Szymaniak.

> -----Original Message-----
> From: Maria Wikström [mailto:maria@ponstudios.se] 
> Sent: Friday, February 18, 2011 7:32 PM
> To: Zhong, Xin
> Cc: Johannes Hirte; linux-btrfs@vger.kernel.org
> Subject: RE: [PATCH v2]Btrfs: pwrite blocked when writing from the mmaped buffer of the same page
> 
> 
> Seems like my reply got eaten by the lists spam filter, so I resend with attachment compressed. Should have thought of that :p
> 
> 
> fre 2011-02-11 klockan 12:39 +0800 skrev Zhong, Xin:
> > Hi,
> > 
> > Could you paste the output of sysrq+t here? Thanks!
> 
> Yes, it's in the attachment. I tried latest btrfs from git (last commit Mon Feb 14 00:45:29 2011 +0000) but it hang so bad that I couldn't get the output from sysrq+t to hit the disk. So the output is from vanilla
> 2.6.37 
> 
> // Maria
> 
> > -----Original Message-----
> > From: Johannes Hirte [mailto:johannes.hirte@fem.tu-ilmenau.de]
> > Sent: Wednesday, February 02, 2011 7:35 AM
> > To: Zhong, Xin
> > Cc: Maria Wikström; linux-btrfs@vger.kernel.org
> > Subject: Re: [PATCH v2]Btrfs: pwrite blocked when writing from the 
> > mmaped buffer of the same page
> > 
> > On Friday 28 January 2011 04:53:24 Zhong, Xin wrote:
> > > Could you describe the steps to recreate it?
> > > It will be a great help for me to look further. Thanks!
> > 
> > It's a little strange. I have to systems with btrfs, both 
> > Gentoo-based. One is affected by this bug the other is not. On the 
> > affected system it is enough to do a 'emerge dev-libs/libgcrypt' that 
> > should normaly compile and install libgcrypt. The emerge command is 
> > part of portage, the package management of Gentoo.
> > The strace output looks similar to the one from Maria:
> > 
> 
> N?????r??y????b?X??ǧv?^?)޺{.n?+????{?n?߲)????w*\x1fjg???\x1e?????ݢj/???z?ޖ??2?ޙ????&?)ߡ?a??\x7f??\x1e?G???h?\x0f?j:+v???w??٥

-- 
Druzyna  futbolowa  tutaj  jest  do  niczego, ale ucze sie troche pilki
noznej.  Trener  mowi,  ze  pilka nozna to futbol dla inteligentnych, a
futbol to futbol dla kretynow.
  -- Stephen King, "The Dead Zone"

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