On Mon, Jan 21, 2008 at 11:50:20PM +0200, Antti Kantee wrote: > On Mon Jan 21 2008 at 15:33:41 -0600, David Young wrote: > > The following crash during shutdown is fairly repeatable. It began > > to happen after I updated to -current from pre-vmlocking2 sources. > > It may be necessary to reproduce my thicket of null mounts in order to > > reproduce the crash, > > > > /dev/wd0a on / type ffs (read-only, local) > > tmpfs on /dev type tmpfs (union, local) > > > > [snip] > > > > unmounting /dev (tmpfs)... > > > > unmounting / (/dev/wd0a)...uvm_fault(0xc0398760, 0xc6984000, 1) -> 0xe > > > > kernel: supervisor trap page fault, code=0 > > You are trying to modify the vnode for /dev/wd0a to update the access time > info, but tmpfs has been garbage collected already when unmounting /dev. > > This is the problem of forcibly unmounting a file system with device > vnodes on it. There was a small discussion about splitting specfs > into two layers: one for the "host" file system (tmpfs in this case) > and one for the actual device info (specfs). Then you could rip the > "host" part out without affecting the device part before the device goes > inactive and can be safely put to rest. I'd actually say this is a bug in deadfs or tmpfs. Since we know the vnode's still in use, we should leave one around that doesn't cause the kernel to crash. Take care, Bill
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