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

[Steven Hartland]

----- Original Message ----- 
From: "Steven Hartland" <smh at freebsd.org>
> ----- Original Message ----- 
> From: "Glen Barber" <gjb at FreeBSD.org>
>> On Sat, Oct 04, 2014 at 03:51:39AM +0100, Steven Hartland wrote:
>> > > [...]
>> > >A possible solution to this is to set kern.kstack_pages=4 via loader(8),
>> > >however in my tests (solely in VirtualBox), this has been ineffective.
>> > >
>> > 
>> > This has been a known issue on i386 since the switch to Clang see UPDATING:
>> > 20121223:
>> >        After switching to Clang as the default compiler some users of ZFS
>> >        on i386 systems started to experience stack overflow kernel panics.
>> >        Please consider using 'options KSTACK_PAGES=4' in such configurations.
>> > 
>> > In my experience your millage may vary but essentially without 4 stack pages
>> > all bets are off in terms of stability.
>> > 
>> 
>> Did you read my email?
> 
> Cleary 4am was too late to be reading emails and my brain didn't ingest the
> "has been ineffective" so sorry for that.
> 
> That said setting options KSTACK_PAGES=4 has more reaching effects than
> kern.kstack_pages=4 so I wonder if you recompiled the kernel with this
> option if you would have any more luck?

Oh and just looking at the code kern.kstack_pages is read only so wont have
any effect, hence you will definitely need to set the kernel option as per
the UPDATING entry.

    Regards
    Steve