The following reply was made to PR kern/42455; it has been noted by GNATS.
From: David Holland <[email protected]>
To: [email protected]
Subject: Re: kern/42455: tstile hang with nfs
Date: Sun, 2 May 2010 01:44:16 +0000
On Fri, Apr 30, 2010 at 11:25:02AM +0000, Christoph Egger wrote:
> 327 2 qemu-dm netbsd 43 netio ffffa0000114f3b8
> 327 1 qemu-dm netbsd 34 genput ffffa000005a0840
> This is the hanging 'qemu-dm' process:
> db> tr /a 0xffffa00026628400
> trace: pid 327 lid 1 at 0xffffa0002661e880
> The question is why does the 'sync' syscall hang in first
> place ?
It looks to me as if pid 327 lid 1 is probably waiting for pid 327 lid
2, which is hanging on the network. It's blocked in genfs_do_putpages
waiting for the page it's trying to write out to become unbusy, and
lid 2 there is a clear candidate for holding it.
I don't immediately see how to inspect the uvm structures to find out
whether this is in fact the case, but maybe someone who knows more
about uvm can help.
(btw, sorry I never got around to answering your previous mail in this
PR... it's been marked unread-and-urgent the last three months. sigh)
David A. Holland