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

From: Trond Myklebust
Date: Sun Jan 14 2007 - 19:15:27 EST


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

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