kern/107171: systat doesn't die when it's xterm is killed while it's running

[Josh Paetzel <josh at tcbug.org>]

>Number:         107171
>Category:       kern
>Synopsis:       systat doesn't die when it's xterm is killed while it's running
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Dec 24 16:00:29 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator:     Josh Paetzel <josh at tcbug.org>
>Release:        FreeBSD 6.1-RELEASE-p11 i386
>Organization:
>Environment:


System: FreeBSD 6.1-RELEASE-p11 #3: Sat Dec 23 19:33:43 CST 2006
    jpaetzel at gimpy.tcbug.org:/usr/obj/usr/src/sys/GIMPY



>Description:


I discovered my CPU at 0% idle this morning.  top reported systat using 95% of the CPU time.  I didn't have systat running anywhere, then remembered I had it running in an xterm last night and killed the xterm without stopping systat.  This seems to be 100% reproducable, but interestingly enough only happens when systat is run as root.  Running systat as a normal user doesn't trigger this behavior.....killing it's xterm kills systat in that case.

It's annoying that systat doesn't die in this situation, the fact that it maxes the CPU is what really makes this a nasty behavior.


>How-To-Repeat:


startx
open 2 xterms
su to root in one of them
start top in the other
systat -if in the root xterm
kill the xterm running systat
watch systat run away to 100% cpu usage


>Fix:


I don't know of a fix but the workaround is:

1) Don't run systat as root
2) Don't kill an xterm with a running systat in it


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