Heads-up: Possible regression between 10.0-RELEASE and 10.1-BETA1 with '/ on ZFS' setup

[Glen Barber]

On Sat, Oct 04, 2014 at 08:46:00PM +0300, Konstantin Belousov wrote:
> On Sat, Oct 04, 2014 at 10:03:48AM -0700, Peter Wemm wrote:
> > > If we cannot increase KSTACK_PAGES by default, do we have any
> > > alternative solution outside of suggesting to avoid using ZFS on i386
> > > with more than one disk?
> > 
> > When zfs creates its kthreads it can specify how much stack it needs.  For 
> > i386 it could ask for more for the zfs threads.  Its not a good option but its 
> > better than more stack for everything when it's already easy to run out 
> > without zfs.
> 
> This one probably happens in the init thread, not some of the zfs hord.
> Glen did not show the backtrace from ddb yet (I hope that ddb did not
> regressed and can step over double-fault boundary).
> 
> We could specifically increment the init thread stack size as well, but
> I have no idea if normal VFS calls into ZFS are affected and cause overflow
> for the normal threads after the multitasking is fired.

As soon as I get the kernel built with debugging support, I'll be able
to get the backtrace.  This, however, is proving to be non-trivial.

Glen

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