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

[Trond Myklebust <trond.myklebust@fys.uio.no>]

On Sun, 2007-01-14 at 17:58 -0600, 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.  After recompiling, I moved
> over to the workstation to reboot it, but the keyboard was not
> functioning ;(
> 
> 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.
> 
> Based on this info, I think we can rule out any USB.  I will try
> testing with NFS3 to see if the problem persists.  Unfortunately there
> is no oops or anything in "dmesg".

Did you try an 'echo t > /proc/sysrq-trigger' in order to find out where
the stat process is hanging?

  Trond