kern/87658: IO::AIO test suite loops infinitely on 5.4-RELEASE-p5

[Niall Murphy]

>Number:         87658
>Category:       kern
>Synopsis:       IO::AIO test suite loops infinitely on 5.4-RELEASE-p5
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Oct 19 12:30:15 GMT 2005
>Closed-Date:
>Last-Modified:
>Originator:     Niall Murphy
>Release:        5.4-RELEASE-p5
>Organization:
Amazon.COM
>Environment:
FreeBSD leonidas.avernus.net 5.4-RELEASE-p5 FreeBSD 5.4-RELEASE-p5 #1: Fri Jul 22 15:02:14 UTC 2005     niallm at leonidas.avernus.net:/usr/obj/usr/src/sys/LEONIDAS  i386
>Description:
Something is wrong somewhere either in the AIO
implementation in FreeBSD, threading in FreeBSD,
or some expectation in how IO::AIO expects the above
to work. Running the test suite, and specifically
test number 2, stat, causes an infinite loop.
>How-To-Repeat:
Download IO::AIO 1.6x from CPAN. (It's probably
sufficient to do perl -eshell -MCPAN install IO::AIO.) Run the test suite with 'make test',
and then watch the suite hang at

t/01_stat.......

Pressing ctrl-T gives the following:

load: 1.51  cmd: perl5.8.6 75059 [runnable] 0.84u 0.07s 2% 2900k
load: 1.51  cmd: perl5.8.6 75059 [runnable] 2.00u 0.16s 6% 2900k
load: 1.58  cmd: perl5.8.6 75059 [runnable] 2.71u 3.34s 20% 2880k
load: 1.62  cmd: perl5.8.6 75059 [runnable] 3.20u 6.06s 28% 2880k

If you ctrl-C out, the test perl process continues running:

niallm at leonidas IO-AIO-1.61 $ ps auxww|grep -i perl
root    74237 53.6  0.6  3676  2916  p6  R    12:09PM  15:01.65 /usr/bin/perl -w t/01_stat.t (perl5.8.6)
niallm  75059 47.5  0.6  3672  2896  p6  R    12:25PM   0:11.92 /usr/bin/perl -w t/01_stat.t (perl5.8.6)

ktracing the processes gives:
leonidas# ktrace -p 74237
leonidas# kdump
 74237 perl5.8.6 PSIG  SIGSEGV SIG_DFL
 74237 perl5.8.6 PSIG  SIGSEGV SIG_DFL
 74237 perl5.8.6 PSIG  SIGSEGV SIG_DFL
 74237 perl5.8.6 PSIG  SIGSEGV SIG_DFL
 74237 perl5.8.6 PSIG  SIGSEGV SIG_DFL
 74237 perl5.8.6 PSIG  SIGSEGV SIG_DFL
 74237 perl5.8.6 PSIG  SIGSEGV SIG_DFL
 74237 perl5.8.6 PSIG  SIGSEGV SIG_DFL
[repeat until dead]

>Fix:
              
>Release-Note:
>Audit-Trail:
>Unformatted: