[OpenAFS] Shutdown Issues on FreeBSD 11.1

[Benjamin Kaduk]

Hi Michael,

On Tue, Apr 24, 2018 at 10:36:09PM -0400, Michael H Lambert wrote:
> A build of OpenAFS 1.8.0 on FreeBSD 11.1 on amd64 (configure with no 
> options) seems to be working properly (at least I can read and write 
> files), but the system panics when stopping afsd:
> 
> # /usr/local/etc/rc.d/afsd onestop
> 
> 
> Fatal trap 12: page fault while in kernel mode
> cpuid = 1; apic id = 01
> fault virtual address   = 0x1d4
> fault code              = supervisor read data, page not present
> instruction pointer     = 0x20:0xffffffff8265ba09
> stack pointer           = 0x28:0xfffffe085df1b5b0
> frame pointer           = 0x28:0xfffffe085df1b5e0
> code segment            = base 0x0, limit 0xfffff, type 0x1b
>                          = DPL 0, pres 1, long 1, def32 0, gran 1
> processor eflags        = interrupt enabled, resume, IOPL = 0
> current process         = 98148 (umount)
> trap number             = 12
> panic: page fault
> cpuid = 3
> KDB: stack backtrace:
> #0 0xffffffff80aaf107 at kdb_backtrace+0x67
> #1 0xffffffff80a6d1e6 at vpanic+0x186
> #2 0xffffffff80a6d053 at panic+0x43
> #3 0xffffffff80eef092 at trap_fatal+0x322
> #4 0xffffffff80eef0eb at trap_pfault+0x4b
> #5 0xffffffff80eee90a at trap+0x2ca
> #6 0xffffffff80ed0500 at calltrap+0x8
> #7 0xffffffff8265b84b at afs_FlushVCache+0x24b
> #8 0xffffffff826d8d08 at afs_vop_reclaim+0x138
> #9 0xffffffff8105e119 at VOP_RECLAIM_APV+0x89

I have also observed this.  Something similar to
https://gerrit.openafs.org/#/c/13014/ will be the ultimate fix, but
I don't think we've reached a decision yet on what exactly the
correct fix should be, so nothing has been merged to the tree yet.

-Ben