kern/163145: FreeBSD 9.0 PRERELEASE freezes without any warnings or panic messages

[Jukka Ukkonen]

>Number:         163145
>Category:       kern
>Synopsis:       FreeBSD 9.0 PRERELEASE freezes without any warnings or panic messages
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Dec 09 07:50:06 UTC 2011
>Closed-Date:
>Last-Modified:
>Originator:     Jukka Ukkonen
>Release:        FreeBSD 9.0 PRERELEASE
>Organization:
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>Environment:
FreeBSD sleipnir 9.0-PRERELEASE FreeBSD 9.0-PRERELEASE #0: Sun Dec  4 13:47:27 EET 2011     root at sleipnir:/usr/obj/usr/src/sys/Sleipnir  amd64
>Description:
When using various application with Gnome2 and X11 the whole system freezes without any warnings, without any messages being logged, and without properly panicing.
The system falls completely unresponsive. The mouse is gone. So are the keyboard and network connections. All disk activity stops. The system will not respond even to a ping.
The only way out of this freeze is a reboot (reset or power buttons).
I have seen this happening at least with Firefox, Thunderbird, and gcalctool.
The freeze does not necessarily hit right after the application starts.
In some cases it has taken some 1/2h to 1h before the problem arises.
Sometimes it happens almost immediately.

The problem has been there through all of the betas and RC snapshots.
The only difference in my locally compiled kernel to the GENERIC kernel is that mine allows multiple fibs.
The same problem happens equally with the GENERIC kernel.

The system on which I have been testing FreeBSD-9.0 is a 12 core AMD64 system.

The problem may be a deadlock which requires some amount of parallellism and a frequent enough stream of some sort of events to appear.

>How-To-Repeat:
Take a multicore / multi-cpu AMD64 system.
Install X11, Gnome2, Firefox, Thunderbird, and gcalctool.
Start using Firefox, etc. on the new Gnome2 desktop.
Sooner or later the system will freeze.
It may take only seconds, but in some cases it has taken almost an hour to occur.

If using gmirror storage volumes, be prepared to see the mirror sides out of sync after the reboot.

>Fix:
I do not have a foggiest idea really. ;-)


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