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Date: Wed, 12 Jun 2013 15:54:17 -0700
From: Alfred Perlstein <bright@mu.org>
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To: Peter Wemm <peter@wemm.org>
Subject: Re: zfs kernel panic,
 known incompatibilities with clang & CPUTYPE/COPTFLAGS?
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Cc: Alexander Leidinger <Alexander@leidinger.net>,
 Dimitry Andric <dim@freebsd.org>, current@freebsd.org
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On 6/12/13 3:10 PM, Peter Wemm wrote:
> On Wed, Jun 12, 2013 at 1:39 PM, Dimitry Andric <dim@freebsd.org> wrote:
>> On Jun 12, 2013, at 22:30, Alexander Leidinger <Alexander@Leidinger.net> wrote:
>>> I try to update from a pre-clang world (r242511M) to "now" (r251618M).
>>> The resulting kernel boots, but while starting some jails (with ezjail
>>> from ports, so fairly late in the boot process) I get a kernel panic
>>> (IIRC zfs trying to access page 0).
>> If you are running on i386, it might be a stack overflow?  Try
>> increasing the stack a little, it might help in that case.
>>
> For i386 I'd be more inclined to suspect KVA exhaustion.
>
> For non-PAE, as a shot in the dark, increase
> options KVA_PAGES=384
> .. the default is 256 for PAE.  that increases kernel KVA from 1GB to 1.5GB.
>
> For a PAE system, this number is multipled by 2, so a corresponding
> change is 512 -> 768.
>
> This is just a shot in the dark.  If this is amd64, then never mind,
> KVA_PAGES is meaningless there.
Is there some way we can get a pps ratelimited (or even one-time) 
message when the kva is almost exhausted?

Could that help people?


-- 
Alfred Perlstein
VP Software Engineering, iXsystems