Subject: Re: Don't use UFS_DIRHASH
To: David Malone <>
From: Reinoud Zandijk <>
List: tech-kern
Date: 08/19/2006 19:44:56
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On Sat, Jul 15, 2006 at 10:36:09AM +0100, David Malone wrote:
> On Wed, Jul 12, 2006 at 12:31:22PM -0400, Thor Lancelot Simon wrote:
> > Removing UFS_DIRHASH from our kernel configuration made the problem go
> > away.  Though it is possible that there is an underlying problem of some
> > kind in one of the allocators that is simply particularly badly exposed
> > by UFS_DIRHASH, it seems more likely that there is a problem (which we
> > haven't found yet) in UFS_DIRHASH itself.  The code has a history of
> > similar problems on FreeBSD which seem to have ended only when the entire
> > kernel synchronization scheme in FreeBSD was reworked in FreeBSD 5.
> FWIW, in FreeBSD I think we've tracked down all outstanding memory
> corruption bugs in which DIRHASH was implicated and they all turned
> out to be problems in other subsystems that used memory allocations
> of the same size. It works fine both in FreeBSD 4, where we have
> spl style synchronisation and in 5+, where the synchronisation is
> mutex based. It is quite possible that we've missed something, but
> we're not seeing any evidence of it in FreeBSD right now.
> The most recent one that we've plugged was one related to IPv6 neighbour
> discovery:

Has anyone looked at this in NetBSD? or is it from a different code base?


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