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

["Maria Wikström" <maria@ponstudios.se>]

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mån 2011-02-21 klockan 09:51 +0800 skrev Zhong, Xin:
> 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...
> 

Haha, yes that's very hard :)

2.6.38-rc6 and btrfs-unstable behaves the same way. I can close the
process with ctrl+c and it disappear a few seconds later. There is no
CPU usage. Reading works because I can start htop and watch "svn info"
disappear, but everything writing to btrfs slows down to a crawl. It
takes about 1 minute to log in. So I had to put the logs on an other
partition using ext3 to get the output from sysrq+t.

// Maria


> -----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:
> > 
> 


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