kern/41202: sysctl_rtable lockup

[yamt%mwd.biglobe.ne.jp@localhost]

>Number:         41202
>Category:       kern
>Synopsis:       sysctl_rtable lockup
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Apr 13 23:35:00 +0000 2009
>Originator:     YAMAMOTO Takashi <yamt%mwd.biglobe.ne.jp@localhost>
>Release:        NetBSD 5.99.10
>Organization:

>Environment:
        
        
System: NetBSD kaeru 5.99.10
Architecture: i386
Machine: i386
>Description:

        1. run ./build.sh -j128 on nfs.
        2. it locks up with a lot of LWPs blocking on sysctl_treelock.
        3. enter into ddb by sending a break and found that an LWP with
           the following backtrace is doing something too long (or infinitely)
           with the lock held.  the request is NET_RT_IFLIST.

db{0}> t
trap() at netbsd:trap+0xb57
--- trap (number 6) ---
copyout(4,bbb58000,0,1,0,d7f9e5e0,1012bec,c049e48e,bbb5f000,d73cd228) at netbsd:
copyout+0x33
sysctl_rtable(dbda2ca8,3,bb82d000,dbda2ccc,0,0,dbda2c9c,dbd09ce0,c4cb7800,c05a2a
20) at netbsd:sysctl_rtable+0xbe
sysctl_dispatch(dbda2c9c,6,bb82d000,dbda2ccc,0,0,dbda2c9c,dbd09ce0,c4cb7800,d8fa
2444) at netbsd:sysctl_dispatch+0xcf
sys___sysctl(dbd09ce0,dbda2d00,dbda2d28,bbb5b000,d8fa2444,d8fa2444,db894c0c,bfbf
e780,6,bb82d000) at netbsd:sys___sysctl+0xd6
syscall(dbda2d48,b3,ab,1f,1f,0,806a6c8,bfbfe708,bbba21d8,6) at netbsd:syscall+0x
cb
db{0}> 

>How-To-Repeat:
        see above.
>Fix:
        

>Unformatted: