Whooops! Looks like the Nortel (microsoft exchange) Gateway had some fun
with my email address on my FreeBSD box (that I use from home)...
Sorry guys the below message is actually from _me_. Please don't bother
Mr. MacPherson, he must rue the day I chose to use my name (as account name)
on this box...
Andrew.
"Macpherson, Andrew (A.) [EXCHANGE:HAL02:HM00-I:NT]" wrote:
>
> On Wed, 16 Dec 1998, David G Andersen wrote:
>
> > Date: Wed, 16 Dec 1998 22:23:53 -0700 (MST)
> > From: David G Andersen <danderse@cs.utah.edu>
> > To: Karl Denninger <karl@Denninger.Net>
> > Cc: bright@hotjobs.com, hackers@FreeBSD.ORG
> > Subject: Re: yup, found it (NFS)
> >
> > Lo and behold, Karl Denninger once said:
> > >
> > > On Wed, Dec 16, 1998 at 11:51:39PM -0500, Alfred Perlstein wrote:
> > > > On Wed, 16 Dec 1998, Karl Denninger wrote:
> > > >
> > > > > Remove the intr for now. If that fixes it then at least we have
> > > > > hard proof of where it is.
> >
> > It does. You may wish to look at PR kern/8732, which we opened about a
> > month ago on exactly this topic.
>
> Yep, I got bit by this while using amd. Updating amd seemed to reduce the
> frequency of the freezes, however one type of freeze was very easy to
> reproduce. While editing a file on an NFS partition with Xemacs, the
> system would consistently lock when Xemacs attempted to auto-save the
> document... it was doing a write to an NFS disk from a SIGALRM handler.
> Alfred's pine behaviour sounds like it might be similar.
>
> David suggested I toast my nfsiod's and since then the system's been
> rock-solid.
>
> As for mount options, I have `intr' enabled...
>
> I wonder if this PR is one of the deadlocks that Matt Dillon referred to
> in his recent mail to the list...
>
> Andrew
>
> >
> > > > > cause. This of course assumes you mount executable directories (very
> > > > > common in clusters) across NFS.
> >
> > Interesting. We didn't bump into this one, but my test program didn't
> > check for it - only for the buffer flushing.
> >
> > > > > Certainly the expected execution path is basically the same, and I can
> > > > > *trigger it* with a SIGINT to a running process which happens to have some
> > > > > of its working set paged out at the time it receives the signal (ouch!)
> > > >
> > > > That doesn't seem very good at all. Is this second case for all
> > > > NFS mounts? or only intr mounts?
> >
> > If it's like the bug we found (which I'd wager), it's probably for intr
> > mounts. Like we mention in the PR, the problem seems to be related to the
> > change from sleep to an interruptable tsleep.
> >
> > > What I want to know is whether a "ro,soft" mount has the same
> > > vulnerability. We use them around here for things like mounting
> > > the Usenet spool.
> >
> > Nope. Soft doesn't seem to affect it (at least, the last time I tested
> > it). Another cheap fix is to not run any nfsiods, preventing the
> > asynchronous flush from occuring in the first place.
> >
> > We've been hounding on this PR for a while (that's kern/8732. :), and
> > would love to see a resolution for it. If someone wants to suggest the
> > proper behavior, I'm more than happy to start drudging up a fix.
> >
> > -Dave
> >
> > --
> > work: danderse@cs.utah.edu me: angio@pobox.com
> > University of Utah http://www.angio.net/
> > Department of Computer Science
> >
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> >
>
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