pmap assertion failure on booke (RB800)

I observe reproducible pmap assertion failure on booke (RB800).
I don't know the exact condition for it, but I always encounter
kernel panic when I try to build pkgsrc/lang/perl5 (NFS root):

   % cd /usr/pkgsrc/lang/perl5; sudo make
   (snip)
   => Checking for portability problems in extracted files
   (snip)
   Use which C compiler? [gcc]
   execve_loadvm: check exec failed 8
   execve_loadvm: check exec failed 8
   execve_loadvm: check exec failed 8
   execve_loadvm: check exec failed 8
   Checking for GNU cc in disguise and/or its version number...
   panic: kernel diagnostic assertion "!VM_PAGEMD_EXECPAGE_P(VM_PAGE_TO_MD(PHYS_TO_VM_PAGE(dst)))" failed: file "/var/build/src/sys/arch/powerpc/booke/booke_pmap.c", line 380
   Stopped in pid 1679.1 (sed) at  netbsd:cpu_Debugger+0xc:        tw      0, r1, r1

The followings are bt and ps in the DDB session:

   db> bt
   0x00951be0: at vpanic+0x13c
   0x00951c10: at kern_assert+0x68
   0x00951c50: at uvmfault_promote+0x16c
   0x00951ca0: at uvm_fault_lower+0x3d8
   0x00951d20: at uvm_fault_internal+0x7f4
   0x00951e50: at pagefault+0x3c
   0x00951e90: at trap+0x470
   0x00951f20: user 0xeffe2730: srr1=0x2d230
               r1=0xffff6220 cr=0x24002208 xer=0 ctr=0xeffe2720
   db> ps
   PID    LID S CPU     FLAGS       STRUCT LWP *               NAME WAIT
   1679 >   1 7   0         0            fb7d3a0                sed
   1963     1 3   0        80            f143960                 sh wait
   753      1 3   0        80            f4853c0                 sh pipe_rd
   1016     1 3   0        80            fc64bc0                 sh wait
   762      1 3   0        80            fc64900               make wait
   717      1 3   0        80            fb7d660                 sh wait
   483      1 3   0        80            fb7dbe0               make wait
   500      1 3   0        80            fc640c0                zsh pause
   542      1 3   0        80            fe30ba0              login wait
   349      1 3   0        80            f485100               cron nanoslp
   432      1 3   0        80            f485680               qmgr kqueue
   492      1 3   0        80            fb7d920             pickup kqueue
   502      1 3   0        80            f485c00             master kqueue
   330      1 3   0        80            f485940               sshd select
   146      1 2   0         0            fb7d0e0            syslogd
   1        1 3   0        80            fe998c0               init wait
   0       40 3   0       200            fe308e0            swapiod swapiod
   0       39 3   0       200            fe300a0           aiodoned aiodoned
   0       38 3   0       200            fe30360            ioflush syncer
   0       37 3   0       200            fe30620           pgdaemon pgdaemon
   0       34 3   0       200            fef55e0              nfsio nfsiod
   0       33 3   0       200            fef5320              nfsio nfsiod
   0       32 3   0       200            fef5060              nfsio nfsiod
   0       31 3   0       200            fe99b80              nfsio nfsiod
   0       29 3   0       200            fe99600              unpgc unpgc
   0       28 3   0       200            fe99340           rt_timer rt_timer
   0       27 3   0       200            fe99080        vmem_rehash vmem_rehash
   0       18 3   0       200            fef58a0            atabus0 atath
   0       17 3   0       200            fef5b60               iic1 iicintr
   0       16 3   0       200            ff2a040               iic0 iicintr
   0       15 3   0       200            ff2a300         pmfsuspend pmfsuspend
   0       14 3   0       200            ff2a5c0           pmfevent pmfevent
   0       13 3   0       200            ff2a880         sopendfree sopendfr
   0       12 3   0       200            ff2ab40           nfssilly nfssilly
   0       11 3   0       200            ff66020            cachegc cachegc
   0       10 3   0       200            ff662e0              vrele vrele
   0        9 3   0       200            ff665a0             vdrain vdrain
   0        8 3   0       200            ff66860          modunload mod_unld
   0        7 3   0       200            ff66b20            xcall/0 xcall
   0        6 1   0       200            ff6a000          softser/0
   0        5 1   0       200            ff6a2c0          softclk/0
   0        4 1   0       200            ff6a580          softbio/0
   0        3 1   0       200            ff6a840          softnet/0
   0        2 1   0       201            ff6ab00             idle/0
   0        1 3   0       200             343600            swapper uvm

I guess that this is due to the recent changes in MI parts of pmap.
Would it be better to send-pr?

Thanks,
Rin