kern/40528: cd(4) hang

[pooka%iki.fi@localhost]

>Number:         40528
>Category:       kern
>Synopsis:       cd(4) hang
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Jan 31 22:55:00 +0000 2009
>Originator:     Antti Kantee
>Release:        5.0_BETA
>Organization:
>Environment:
>Description:
In some circumstances, the cd driver can hang a userspace process
when ioctl(2) is called.  The process stack trace, copied
by hand from ddb, is (relevant parts only):
  cdioctl
  mmc_getdiscinfo
  read_cd_capacity
  scsipi_execute_xs
  sleepq_block

And the process hangs with the "xscmd" wchan.
>How-To-Repeat:
maybe: run rump_udf, copy large file to the file system, decide to abort
and accidentally kill rump_udf instead of the cp, try to remount,
observe stuck unkillable process.
>Fix:
unknown