Locked up processes after upgrade to ZFS v15

[Jeremy Chadwick]

On Tue, Oct 12, 2010 at 03:07:09AM -0700, Jeremy Chadwick wrote:
> On Tue, Oct 12, 2010 at 12:52:15AM +0300, Andriy Gapon wrote:
> > on 11/10/2010 21:37 Jeremy Chadwick said the following:
> > > EnableMMAP on
> > > EnableSendfile on
> > 
> > Yes, it is it.
> > 
> > Jeremy, Kai,
> > could you please try to test this patch?
> > http://people.freebsd.org/~avg/zfs-mappedread-sendfile.diff
> > 
> > Kostik,
> > could you please review it?
> 
> Andriy,
> 
> I've been trying to reproduce this problem on my testbed box without
> much luck so far.  The box differs severely -- the biggest differences
> being the testbed runs i386 (due to CPU), only has 1GB RAM, and is
> single-core.  I don't have an amd64 testbed system on hand right now.
> 
> I've been trying to reproduce it by enabling Sendfile and MMAP in Apache
> on the system, putting up some very large files on an Apache-accessible
> ZFS filesystem, and using something like "wget -r" to download
> everything.  I've been watching "netstat -m" to monitor the number of
> sendfile requests.
> 
> There have been a couple cases where I've seen processes go into "zfs"
> state, but I have yet to see any lock up.
> 
> Is there something amd64-specific to the problem at hand, or maybe some
> VM feature which isn't getting triggered on i386?  Or do you know of a
> reliable way to reproduce the issue at this point?

An additional question/point of interest:

The testbed (i386) box I'm using is built from RELENG_8 sources dated
October 11th around 20:00 PDT.

I went looking through RELENG_8 commits and I found this committed
approximately 25 hours ago:

http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_znode.c#rev1.24.2.8

The testbed/i386 box therefore has the above commit.  Could this
commit be the fix for the problem?

In the meantime, I'm going to try rolling back my RELENG_8 src-all on
the testbed/i386 box to October 8th and then re-try my tests to see if
the problem happens.

-- 
| Jeremy Chadwick                                   jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |