svn commit: r294329 - in head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs: . sys

[Slawa Olhovchenkov]

On Thu, Jan 21, 2016 at 08:03:25AM -0700, alan somers wrote:

> On Thu, Jan 21, 2016 at 4:38 AM, Slawa Olhovchenkov <slw at zxy.spb.ru> wrote:
> > On Thu, Jan 21, 2016 at 01:34:57AM +0200, Andriy Gapon wrote:
> >
> >> On 20/01/2016 22:03, Alan Somers wrote:
> >> > On Wed, Jan 20, 2016 at 2:20 AM, Andriy Gapon <avg at freebsd.org> wrote:
> >> >> On 19/01/2016 19:20, Alan Somers wrote:
> >> >>> The thing is, it never really worked in the first place.  Panics and
> >> >>> deadlocks are so frequent that I don't think the feature was usable
> >> >>> for anybody.
> >> >>
> >> >> The feature is perfectly usable for me.  I have never run into the problems that
> >> >> you describe.  Why not fix the real bugs that you've run into?
> >> >
> >> > Spectra Logic and iXSystems both experienced many problems with this.
> >> > The worst is a deadlock that can be triggered simply by pulling a
> >> > drive from a redundant pool when there exists a zvol anywhere in the
> >> > system (see https://reviews.freebsd.org/D4998 for a quick way to
> >> > reproduce).  Fixing it correctly would likely require far more time
> >> > than I have available.  I just want the bugs to go away.  See that
> >> > same code review for a change to make the feature optional.
> >>
> >> I think that we all want all the bugs to go way.  One way to remove bugs is to
> >> remove (disable) code that contains bugs.  That way the perfect bug-free
> >> software is clearly achievable :-)  Unfortunately, that technique is not always
> >> welcomed.
> >>
> >> P.S.
> >> I think that the real problem here is that a method of a geom must never drop
> >> topology_lock.  In other words, the GEOM management code (like g_xxx() stuff in
> >> geom_subr.c) expects that a topology can not change underneath it.  But
> >> zvol_geom_access() clearly breaks that contract.
> >
> > May be same cause problem with swap on zvol (don't test on latest
> > -stable)?
> 
> I'm not familiar with that problem.  Is there a PR?

I am find PR 199189.
My expirense slightly different: VirtualBox VM with test install (384M
RAM) hang, not crashed, just infinite wait somewhere. Tested on 10.1.