i386/79990: ng_mppc_decompress dies with ADAPTIVE_GIANT and PREEMTION

[Arcadiy Ivanov]

>Number:         79990
>Category:       i386
>Synopsis:       ng_mppc_decompress dies with ADAPTIVE_GIANT and PREEMTION
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    freebsd-i386
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Apr 16 03:30:25 GMT 2005
>Closed-Date:
>Last-Modified:
>Originator:     Arcadiy Ivanov
>Release:        5.4-RC2
>Organization:
>Environment:
FreeBSD fw1.home.ivanovy.net 5.4-RC2 FreeBSD 5.4-RC2 #0: Fri Apr 15 16:13:59 EDT 2005     administrator at fw1.home.ivanovy.net:/usr/obj/usr/src/sys/DELLGX2  i386

>Description:
If the kernel of 5.3 or 5.4-RC2 is built with either PREEMTION *OR* ADAPTIVE_GIANT options enabled and mpd-3.18_2 is installed, then after pptp connection is established and runs for a certain time the following kernel message is logged:

Apr 15 20:40:58 fw1 kernel: ng_mppc_decompress: too many (4094) packets dropped, disabling node 0xc2248800!

Then connection is not dropped but times out after a while with no traffic going in either direction. The problem is always reproducible.
>How-To-Repeat:
Build a kernel with ADAPTIVE_GIANT or PREEMPTION options enabled.
Install and configure port mpd-3.18_2.
Start mpd daemon.
Establish a connection and begin transfer. After a period of time the above message is always logged and a connection stalls.
>Fix:
Remove PREEMTION and ADAPTIVE_GIANT options from the kernel and add NO_ADAPTIVE_MUTEXES option. Rebuild kernel. Reboot. Launch mpd daemon. No connection drops happen.
>Release-Note:
>Audit-Trail:
>Unformatted: