nullfs broken on powerpc

[Kostik Belousov]

On Tue, Jan 24, 2012 at 06:31:52PM +0100, Milan Obuch wrote:
> Hi,
> 
> as I succesfully installed FreeBSD on Mac Mini (older powerpc model
> with G4 CPU) I tried to use mount_nullfs to share some files for more
> systems. I use this method for years on i386 and amd64 platforms for
> years now to share sources and other files.
> 
> Basically I want to have small system specific slice/partition and
> large shared data area. System sources are in shared area as well as
> some working area (think /usr/src and /usr/obj directories).
> 
> This does not work with powerpc for me. With sources csup'ped this
> morning, full system rebuild with GENERIC kernel, it is enough for me
> to issue
> 
> mount_nullfs /data/src10 /usr/src
> csup /usr/share/examples/cvsup/standard-supfile
> 
> and system panic occurs, with following on system console:
> 
> panic: mtx_lock() of spin mutex (null) @ /usr/src/sys/kern/vfs_subr.c:2670
> cpuid = 0
> KDB: enter: panic
> [ thread pid 1442 tid 100095 ]
> Stopped at 0x40f734: addi r0, r0, 0x0
> db>
> 
> At this point, I am able to interact with system, the question for me
> is what I want to get from it :) I tried bt with following result:
> 
> Tracing pid 1442 tid 100095 td 0x2d6b000
> 0xe22c26d0: at panic+0x274
> 0xe22c2730: at _mtx_lock_flags+0xc4
> 0xe22c2760: at vgonel+0x330
> 0xe22c27b0: at vrecycle+0x54
> 0xe22c27d0: at null_inactive+0x30
> 0xe22c27f0: at VOP_INACTIVE_APV+0xdc
> 0xe22c2810: at vinactive+0x98
> 0xe22c2850: at vputx+0x344
> 0xe22c28a0: at vput+0x18
> 0xe22c28c0: at kern_statat_vnhook+0x108
> 0xe22c29d0: at kern_statat+0x18
> 0xe22c29f0: at kern_lstat+0x2c
> 0xe22c2a10: at sys_lstat+0x30
> 0xe22c2a90: at trap+0x388
> 0xe22c2b60: at powerpc_interrupt+0x108
> 0xe22c2b90: user SC trap by _end+0x40d88c70: srr1=0xd032
>             r1=0xffaf9a70 cr=0x28004044 xer=0x20000000 ctr=0x41a0ac40
> db>
> 
> Does this shed any light for someone with more knowledge here? My gut
> feeling is there is some endianness issue at play, the same nullfs
> usage works for me flawlessly on both i386 and amd64 systems, so it
> could not be 32 vs 64 bit issue at least.
> 
> At line 2670 of /usr/src/sys/kern/vfs_subr.c I see end of function void
> vgonel(struct vnode *vp)
> 
>         VI_LOCK(vp);
>         vp->v_vnlock = &vp->v_lock;
>         vp->v_op = &dead_vnodeops;
>         vp->v_tag = "none";
>         vp->v_type = VBAD;
> }
> 
> so the question seems to be reduced to 'why is vp null?' or is my small
> attempt on analyse flawed...
I do not think that the vp is null. It more look like the *vp memory
was zeroed. This has very low chances of being related to endianess, and
more like a kernel memory corruption.

Take a dump and print the content of *vp.
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