Forwarding to gcl-devel:
------- Start of forwarded message -------
Date: Wed, 25 Feb 2009 14:10:58 -0600
From: "David A. Kotz" <dk...@cs.utexas.edu>
To: Matt Kaufmann <kaufm...@cs.utexas.edu>
CC: c...@maguirefamily.org, gr...@cs.utexas.edu, gcl-devel@gnu.org
Subject: Re: interrupts in 64-bit GCL
In-Reply-To: <200902252007.n1pk7mv5025...@lhug-8.cs.utexas.edu>
./configure --prefix=/lusr/opt/gcl-2.6.8pre \
--disable-statsysbfd --enable-locbfd \
--enable-ihssize=2097110 \
--enable-vssize=2097110 \
--enable-maxpage=524288 \
--enable-holediv=100 \
--enable-debug
Matt Kaufmann wrote:
> Great! Thank you. Dave, if you send me your build instructions, I'll
> forward them along since you're (I'm guessing) not on the gcl-devel
> list, which only allows posts from members.
>
> Thanks --
> -- Matt
> Cc: dk...@cs.utexas.edu, gr...@cs.utexas.edu, gcl-devel@gnu.org
> From: Camm Maguire <c...@maguirefamily.org>
> Date: Wed, 25 Feb 2009 15:03:41 -0500
> X-SpamAssassin-Status: No, hits=-2.6 required=5.0
> X-UTCS-Spam-Status: No, hits=-282 required=165
>
> Greetings! OK, suprisingly enough I think I might have indirectly
> deduced what is going on. It is verifiably independent of SGC, but
> appears related to 64bit only by the enhanced time window possible in
> which to receive SIGINT.
>
> In short, could you please send me (and post to gcl-devel) the
> instructions for rebuilding your source again against a patched gcl
> tree for testing.
>
> This does bring up the legacy gcl signal handling code, which is quite
> clever given the age in which it was developed, but has since been
> made somewhat obsolete by recent system developments, at least on
> Linux.
>
> The GCL strategy is to maintain global variables tracking pending and
> blcked signals, and to loop over alarm(1) until the unblocking code
> snippet is executed. (i.e. BEGIN_NO_INTERRUPT and END_NO_INTERRUPT,
> which essentially set signals_allowed to 0 and restores the previous
> value respectively). Nowadays, bracketing the code needing protection
> directly with sigprocmask is more typical. Heaven knows what
> portability issues are involved in making this change.
>
> The bug appears to be that critical GC code is not protected against
> interrupts and subsequent possible longjumps. Specifically,
> add_page_to_freelist is apparently allowing partially initialized
> freelists to escape. An immediate fix would be at hand in this case,
> but more systematically we need to review the areas this protection is
> required and come up with a decent centralization policy. I don't
> think there is any reason to clock signals other that object creation,
> gc, and anything modifying tm_table. Other thoughts most welcome.
>
> Take care,
>
>
>
> Matt Kaufmann <kaufm...@cs.utexas.edu> writes:
>
> > Hi --
> >
> > I was able to reproduce the error after building ACL2 a new debug copy
> > of 64-bit gcl that the sysadmins built. Same instructions as before,
> > except for a slight change in the ACL2 executable directory. Quoting
> > from below, but updating the executable path (and fixing a misleading
> > comment):
> >
> > Start up ACL2 built on GCL, as follows:
> >
> > /projects/acl2/v3-4-linux-64/fast-linux-gcl-saved_acl2
> >
> > Then issue these commands:
> >
> > ; Just to slow down the output from the thm form below:
> > (trace$ rewrite)
> >
> > ; ACL2 disables the debugger by default; this restores it:
> > (set-debugger-enable t)
> >
> > ; This goes pretty fast but you'll have time to interrupt it:
> > (thm (equal (append (append x x) x) (append x x x)))
> >
> > [Now quickly interrupt with control-c, and then :q from the break.
> > If the form above completes, just try it again. Eventually I think
> > you'll see a Lisp "fatal error" or even a "Segmentation fault".]
> >
> > It seems to take me about 3 to 5 THM calls to get the error, which
> > looks like this:
> >
> > ACL2 !>(thm (equal (append (append x x) x) (append x x x)))
> > [SGC off]
> > Error: Caught fatal error [memory may be damaged]
> > Fast links are on: do (si::use-fast-links nil) for debugging
> > Error signalled by ACL2_*1*_ACL2::THM-FN.
> > Broken at COND. Type :H for Help.
> > ACL2[RAW LISP]>>
> >
> > -- Matt
> > Date: Mon, 23 Feb 2009 17:12:04 -0600
> > From: "David A. Kotz" <dk...@cs.utexas.edu>
> > CC: c...@maguirefamily.org, gr...@cs.utexas.edu, gcl-devel@gnu.org
> >
> > I've replaced both of our 64bit flavors and the 32bit with
> debug-enabled
> > versions. The 64s are in place now, and the 32 should rdist around
> > tonight. I want to keep all of them in sync, even if we're only
> > investigating a problem in one.
> >
> > - dave
> >
> >
> > Matt Kaufmann wrote:
> > > Thanks, Dave! I really appreciate it.
> > >
> > > When I get the word from you, or when I see
> > > /lusr/opt/gcl-2.6.8pre/bin/gcl updated on lhug-0, I'll rebuild ACL2
> on
> > > top of it and try to reproduce the problem.
> > >
> > > Thanks again --
> > > -- Matt
> > > Date: Mon, 23 Feb 2009 10:13:54 -0600
> > > From: "David A. Kotz" <dk...@cs.utexas.edu>
> > > CC: Matt Kaufmann <kaufm...@cs.utexas.edu>, gr...@cs.utexas.edu,
> > > gcl-devel@gnu.org
> > >
> > > I'll rebuild it with the debug flag.
> > >
> > > - dave
> > >
> > >
> > > Camm Maguire wrote:
> > > > Thanks! Please let me know if you run into troubles here.
> > > >
> > > > Take care,
> > > >
> > > > Matt Kaufmann <kaufm...@cs.utexas.edu> writes:
> > > >
> > > >> Howdy --
> > > >>
> > > >> Thanks for the reply.
> > > >>
> > > >> If gr...@cs is willing to do (1), or to send me the exact
> configure
> > > >> and make commands and source directory used so that I can do
> it
> > > >> myself, then I'll try to reproduce the error by building ACL2
> on top
> > > >> of it. I'm assuming that --enable-debug is given to the
> configure
> > > >> command, not to make.
> > > >>
> > > >> Then if if I can't reproduce the problem, I'll let you and
> gr...@cs
> > > >> know and we can explore (2). In that case, if gr...@cs is
> willing to
> > > >> do it, great; then I'll try to reproduce the problem. But if
> I'm to
> > > >> do the build, I'd need explicit instructions on how to "make
> sure -g
> > > >> is included in the gcc calls"; maybe I need to do some setq
> in Lisp?
> > > >> Also I didn't understand the comment about makedefs. But I
> guess we
> > > >> can ignore (2) if (1) works.
> > > >>
> > > >> -- Matt
> > > >> Cc: gcl-devel@gnu.org, gr...@cs.utexas.edu
> > > >> From: Camm Maguire <c...@maguirefamily.org>
> > > >> Date: Fri, 20 Feb 2009 20:58:49 -0500
> > > >> X-SpamAssassin-Status: No, hits=-2.6 required=5.0
> > > >> X-UTCS-Spam-Status: No, hits=-282 required=165
> > > >>
> > > >> Greetings! I suspect a missing signal block around some
> code that
> > > >> needs protecting. I've reprodced under gdb, but there are
> no
> > > >> debugging symbols in the image. [ Question for list --
> have computers
> > > >> now become so fast that -g should be included by default
> in all gcl
> > > >> images? It used to slow down the compiler, don't know
> about now. It
> > > >> does make the image quite a bit bigger. ]
> > > >>
> > > >> Ideally, you or someone else at the site might be so kind
> as to
> > > >> rebuild atop
> > > >>
> > > >> 1) a gcl build with --enable-debug. If this does not
> reproduce, then
> > > >> in addition
> > > >> 2) rebuild atop a standard gcl with the CFLAGS environment
> variable
> > > >> set to -g before configure and make. Please make sure -g
> is included
> > > >> in the gcc calls. Otherwise, makedefs can be modified
> after configure
> > > >> and before make to include -g wherever one sees -O3 or -O
> > > >>
> > > >> Would this be too much trouble?
> > > >>
> > > >> Take care,
> > > >>
> > > >> Matt Kaufmann <kaufm...@cs.utexas.edu> writes:
> > > >>
> > > >> > Hi --
> > > >> >
> > > >> > The sysadmins here at UT CS have built GCL 2.6.8pre from
> CVS as you
> > > >> > suggested. It's working great on 32-bit linux, but I've
> run into an
> > > >> > issue for 64-bit linux.
> > > >> >
> > > >> > You can re-create the issue on a UT CS 64-bit linux
> machine as
> > > >> > follows.
> > > >> >
> > > >> > Start up ACL2 built on GCL, as follows:
> > > >> >
> > > >> > /projects/acl2/v3-4-linux/fast-linux-gcl-saved_acl2
> > > >> >
> > > >> > Then issue these commands:
> > > >> >
> > > >> > ; Just to slow down the output from the next form:
> > > >> > (trace$ rewrite)
> > > >> >
> > > >> > ; ACL2 disables the debugger by default; this restores
> it:
> > > >> > (set-debugger-enable t)
> > > >> >
> > > >> > ; This goes pretty fast but you'll have time to
> interrupt it:
> > > >> > (thm (equal (append (append x x) x) (append x x x)))
> > > >> >
> > > >> > [Now quickly interrupt with control-c, and then :q
> from the break.
> > > >> > If the form above completes, just try it again.
> Eventually I think
> > > >> > you'll see a Lisp "fatal error" or even a
> "Segmentation fault".]
> > > >> >
> > > >> > By the way, I built
> /projects/acl2/v3-4-linux/fast-linux-gcl as
> > > >> > follows, on lhug-0 (a 64-bit linux machine):
> > > >> >
> > > >> > rm -f TAGS ; mv make-fast-gcl.log make-fast-gcl.old.log
> ; (time nice make PREFIX=fast-linux-gcl- LISP=my-fast-gcl) >&
> make-fast-gcl.log&
> > > >> >
> > > >> > where "my-fast-gcl" is a script containing:
> > > >> >
> > > >> > #!/bin/sh
> > > >> > /lusr/opt/gcl-2.6.8pre/bin/gcl -eval "(defparameter
> user::*fast-acl2-gcl-build* t)" $*
> > > >> >
> > > >> > Also by the way, if you instead run the following on a
> 32-bit UT CS
> > > >> > linux machine
> > > >> >
> > > >> > /projects/acl2/v3-4-linux/gcl-saved_acl2
> > > >> >
> > > >> > then you won't see the interrupt problem described above
> (or at least,
> > > >> > I didn't, and I tried).
> > > >> >
> > > >> > Thanks --
> > > >> > -- Matt
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >>
> > > >> --
> > > >> Camm Maguire
> c...@maguirefamily.org
> > > >>
> ==========================================================================
> > > >> "The earth is but one country, and mankind its citizens."
> -- Baha'u'llah
> > > >>
> > > >>
> > > >>
> > > >>
> > > >
> >
> >
> >
> >
>
> --
> Camm Maguire
> c...@maguirefamily.org
> ==========================================================================
> "The earth is but one country, and mankind its citizens." -- Baha'u'llah
------- End of forwarded message -------
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