i386/66966: MD devices trash system

[Wim]

>Number:         66966
>Category:       i386
>Synopsis:       MD devices trash system
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    freebsd-i386
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu May 20 16:10:19 PDT 2004
>Closed-Date:
>Last-Modified:
>Originator:     Wim
>Release:        5.2.1, 5.2, 5.0
>Organization:
>Environment:
DEFAULT kernels on 5 machines
>Description:
MD devices lock up when beeing used intensively, eating up all CPU time and disabeling other programs to be executed; in the end the machines just hang; rebooting is not possible unless done by physically resetting the server by turning it off and back one. Terminating the MD device or unmounting it seems to be impossible.
>How-To-Repeat:
Manifests on all Intel P2 Celeron, P3 and P4 I've tested, but not on AMD; simply create an MD-virtual disk and use it intensively by compiling a program on it for example or building a world to it.
Tested on multiple BSD installations; though BSD 5.0 seems to have less problems with it then 5.2.1.
>Fix:
Unkown
>Release-Note:
>Audit-Trail:
>Unformatted: