linux-kernel - Re: heavy nfs[4]] causes fs badness Was: 2.6.20-rc4: known unfixed regressions (v2)

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Date:	Sun, 14 Jan 2007 20:02:21 -0600
From:	florin@...ha.net (Florin Iucha)
To:	Jiri Kosina <jikos@...os.cz>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-usb-devel@...ts.sourceforge.net,
	Adrian Bunk <bunk@...sta.de>,
	Alan Stern <stern@...land.harvard.edu>,
	Trond Myklebust <trond.myklebust@....uio.no>
Subject: Re: heavy nfs[4]] causes fs badness Was: 2.6.20-rc4: known unfixed regressions (v2)

Jiri and Trond,

On Mon, Jan 15, 2007 at 01:14:09AM +0100, Jiri Kosina wrote:
> On Sun, 14 Jan 2007, Florin Iucha wrote:
> 
> > All the testing was done via a ssh into the workstation.  The console 
> > was left as booted into, with the gdm running.  The remote nfs4 
> > directory was mounted on "/mnt". After copying the 60+ GB and testing 
> > that the keyboard was still functioning, I did not reboot but stayed in 
> > the same kernel and pulled the latest git then started bisecting.  
> 
> Hi Florin,
> 
> thanks a lot for the testing. Just to verify - what kernel is 'the same 
> kernel' mentioned above? (just to isolate whether the problem is really 
> somewhere between 2.6.19 and 2.6.20-rc2, as you stated in previous posts, 
> or the situation has changed).

This happened with 2.6.19.  It worked last time, but I wanted to test
again, to make sure.  This time, it bombed, but half an hour after the 
transfer finished.

> > After recompiling, I moved over to the workstation to reboot it, but the 
> > keyboard was not functioning ;(
> 
> So this time the hang occured when the system was idle, not during the 
> transfers, right?

Yes it was idle.  Immediately after the transfer finished, the keyboard was
still functioning.  It "hang" minutes later, after the first bisected kernel
was compiled and installed.

> > I ran "lsusb" and it displayed all the devices. "dmesg" did not show
> > any oops, anything for that matter.  I have unplugged the keyboard and
> > run "lsusb" again, but it hang.  I ran "ls /mnt" and it hang as well.
> > Stracing "lsusb" showed it hang (entered the kernel) at opening the device
> > that used to be the keyboard.  Stracing "ls /mnt" showed that it
> > hang at "stat(/mnt)".  Both processes were in "D" state.  "ls /root"
> > worked without problem, so it appears that crossing mountpoints causes
> > some hang in the kernel.
> 
> Could you please do alt-sysrq-t (or "echo t > /proc/sysrq-trigger" via 
> ssh, when your keyboard is dead) to see the calltraces of the processes 
> which are stuck inside kernel?
> 
> You will probably get a lot of output after the sysrq, so please either 
> put it somewhere on the web if possible, or just extract the interesting 
> processes out of it (mainly the ones which are stuck).

Will do.

florin

-- 
Bruce Schneier expects the Spanish Inquisition.
      http://geekz.co.uk/schneierfacts/fact/163

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