zfs discuss - Jul 2006 - S10U2: zfs instant hang with dovecot imap server using mmap

Hi,
  I just upgraded my home box to run Solaris 10 6/06 and converted my previous
filesytems over to ZFS, including /var/mail.  Previously on S10 FCS I was
running dovecot mail server from blastwave.org without issue.  On upgrading to
Update 2 I have found that the mail server hangs frequently.  The imap process
cannot be killed, dtraced, pstacked or trussed.  After a few goes at dtrace I
took a core dump and had a look at that.  The stack for the imap process was
simply:
> 0t1550::pid2proc|::walk thread|::findstack -v
stack pointer for thread d77f8600: d41e8e2c
  d41e8e78 0xd41e8e44(20000, d41e8f44)
  d41e8ed8 zfs_write+0x59f(d6a273c0, d41e8f44, 0, d8adee10, 0)
  d41e8f0c fop_write+0x2d(d6a273c0, d41e8f44, 0, d8adee10, 0)
  d41e8f8c write+0x29a()
  d41e8fb4 sys_sysenter+0xdc()

Some digging in sunsolve I found a few references to mmap and zfs_write locks -
so on a hunch (because fuser previously showed my mailfile as mmaped) I disabled
mmap in the dovecot configuration, and I no longer get the deadlocks.

I could not find an exact bug in sunsolve - is this a known one or is more work
needed?  I can provide the core file or SSH access to the box if more analysis
is needed.

Cheers,
  Adrian
 
 
This message posted from opensolaris.org

Oh - and by instant hang I mean I can reproduce it simply by rebooting, enabling
the dovecot service and then connecting to dovecot with thunderbird.
 
 
This message posted from opensolaris.org

There are also a number of procmail processes with the following thread stacks
> 0t1611::pid2proc|::walk thread|::findstack -v
stack pointer for thread d8ae1a00: d3bcbbac
[ d3bcbbac 0xfe826b37() ]
  d3bcbbc4 swtch+0x13e()
  d3bcbbe8 cv_wait_sig+0x119(da58fb4c, d46a8680)
  d3bcbc00 wait_for_lock+0x30(da58fac8)
  d3bcbc20 flk_wait_execute_request+0x156(da58fac8)
  d3bcbc64 flk_process_request+0x4c7(da58fac8)
  d3bcbd38 reclock+0x3a9(d6a273c0, d3bcbe64, 6, 10a, 202e92c, 0)
  d3bcbd8c fs_frlock+0x252(d6a273c0, 7, d3bcbe64, 10a, 202e92c, 0)
  d3bcbdc0 zfs_frlock+0x73(d6a273c0, 7, d3bcbe64, 10a, 202e92c, 0)
  d3bcbdf8 fop_frlock+0x2c(d6a273c0, 7, d3bcbe64, 10a, 202e92c, 0)
  d3bcbf8c fcntl+0x95d()
  d3bcbfb4 sys_sysenter+0xdc()
 
 
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