Subject: kern/24715: system can stuck with no available ram when using swap on cgd(4)
To: None <gnats-bugs@gnats.netbsd.org>
From: Lubomir Sedlacik <salo@Xtrmntr.org>
List: netbsd-bugs
Date: 03/09/2004 13:35:03
>Number:         24715
>Category:       kern
>Synopsis:       system can stuck with no available ram when using swap on cgd(4)
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Mar 09 12:36:00 UTC 2004
>Closed-Date:
>Last-Modified:
>Originator:     Lubomir Sedlacik
>Release:        NetBSD 1.6ZI
>Organization:
>Environment:
Architecture: i386
Machine: i386
>Description:
System using swap on a cgd(4) device could stuck when it runs out of free
memory but there is still plenty of swap space available.  the problem seems
to be that cgd(4) doesn't have enough memory to decrypt/encrypt swap pages.

i was able to unfreeze the system for a moment by killing processes from ddb
(when i was lucky enough and was able to get into ddb) but never to fully
recover.  the issue is repeatable.

Roland Dowdeswell is aware of this issue, i filled the PR so it won't be
forgotten.

>How-To-Repeat:
use swap on cgd(4), make the machine use all the available ram, observe it
hang.
>Fix:
N/A
use memory pools?
>Release-Note:
>Audit-Trail:
>Unformatted: