NFS deadlock on 9.2-Beta1

[J David]

On Thu, Aug 15, 2013 at 5:39 PM, Rick Macklem <rmacklem at uoguelph.ca> wrote:
> Have you been able to pass the debugging info on to Kostik?
>
> It would be really nice to get this fixed for FreeBSD9.2.

You're probably not talking to me, but headway here is slow.  At our
location, we have been continuing to test releng/9.2 extensively, but
with r250907 reverted.  Since reverting it solves the issue, and since
there haven't been any further changes to releng/9.2 that might also
resolve this issue, re-applying r250907 is perceived here as un-fixing
a problem.  Enthusiasm for doing so is correspondingly low, even if
the purpose is to gather debugging info. :(

However, after finally having clearance to test releng/9.2 r254540
with r250907 included and with DDB on five nodes.  The problem cropped
up in about an hour.  Two threads in one process deadlocked, was
perfect.  Got it into DDB and saw the stack trace was scrolling off so
there was no way to copy it by hand.  Also, the machine's disk is
smaller than physical RAM, so no dump file. :(

Here's what is available so far:

db> show proc 33362

Process 33362 (httpd) at 0xcd225b50:

 state: NORMAL

 uid: 25000 gids: 25000

 parent: pid 25104 at 0xc95f92d4

 ABI: FreeBSD ELF32

 arguments: /usr/local/libexec/httpd

 threads: 3

100405 D newnfs 0xc9b875e4 httpd

100393 D pgrbwt 0xc43a30c0 httpd

100755 S uwait 0xc84b7c80 httpd


Not much to go on. :(  Maybe these five can be configured with serial consoles.

So, inquiries are continuing, but the answer to "does this still
happen on 9.2-RC2?" is definitely yes.

Thanks!