file system deadlock in -CURRENT

[Daniel Rock]

Hi,

I found an interesting problem during tracing my perl-5.8 problem I mailed some days ago.

Sometimes - I cannot forcibly reproduce this event - while I'm trying to truss a process, I first get the following error message:

/usr/ports/lang/perl5.8/work/perl-5.8.0# truss ./perl
truss: cannot open /proc/44502/mem: No such file or directory
or the following error message:
/usr/ports/lang/perl5.8/work/perl-5.8.0# truss ./perl
truss: PIOCWAIT: Input/output error

And then I cannot enter this directory any more. Every process trying to access /usr/ports/lang/perl5.8/work/5.8.0 hangs in an uninterruptible sleep:
/# cd /usr/ports/lang/perl5.8
/usr/ports/lang/perl5.8# ls
CVS/ distinfo pkg-comment pkg-install* pkg-plist work/
Makefile files/ pkg-descr pkg-message test.log
/usr/ports/lang/perl5.8# cd work
/usr/ports/lang/perl5.8/work# ls
BSDPAN-5.8.0/ perl-5.8.0/ use.perl
/usr/ports/lang/perl5.8/work# cd perl-5.8.0
/usr/ports/lang/perl5.8/work/perl-5.8.0# ls
[at this point the shell (or any other process) hangs. I can otherwise use the machine as usual but cannot access this directory]

Only solution to revive the directory again is a reboot.

I have recompiled the kernel with
options WITNESS
options MUTEX_DEBUG

One lock order reversal was logged by the kernel 3 hours earlier:
lock order reversal
1st 0xc05a1fe0 spechash (spechash) @ ../../../kern/vfs_subr.c:2748
2nd 0xc17866f0 vnode interlock (vnode interlock) @ ../../../kern/vfs_subr.c:2751
(possibly unrelated)


The last time I had this problem I also had a kernel panic (but no crash dump or console output during the crash - possibly also unrelated. I still have reliability problems during heave file system activity). I'm trying to reproduce this error again, then hopefully with a crash dump.


Daniel


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