From: Eli Zaretskii <eliz@gnu.org>
To: Alan J Third <alan@idiocy.org>
Cc: larsi@gnus.org, markus.triska@gmx.at, 2099@debbugs.gnu.org
Subject: bug#2099: 23.0.60; `mark_object' with larger nested objects crashes Emacs
Date: Mon, 11 Jan 2016 17:11:44 +0200 [thread overview]
Message-ID: <83vb70kv67.fsf@gnu.org> (raw)
In-Reply-To: <m21t9p6q4l.fsf@galloway.idiocy.org> (message from Alan J Third on Sun, 10 Jan 2016 22:12:10 +0000)
> From: Alan J Third <alan@idiocy.org>
> Date: Sun, 10 Jan 2016 22:12:10 +0000
> Cc: Markus Triska <markus.triska@gmx.at>, 2099@debbugs.gnu.org
>
> > Markus Triska <address@hidden> writes:
> >
> >> When you do:
> >>
> >> $ emacs -Q --eval "(let (v) (while t (setq v (cons v v))))"
> >>
> >> then Emacs crashes with:
> >>
> >> Program received signal EXC_BAD_ACCESS, Could not access memory.
> >> Reason: KERN_INVALID_ADDRESS at address: 0xbf7ffffc
> >> 0x0013bc1a in mark_object (arg=40166541) at alloc.c:5372
> >> (gdb) bt
> >> #0 0x0013bc1a in mark_object (arg=40166541) at alloc.c:5372
> >
> > I can confirm that the crash is still present in Emacs 24:
>
> And Emacs 25:
>
> Fatal error 11: Segmentation fault
Of course: this is expected.
I admit I don't really understand what is the purpose of this bug
report; perhaps the OP could clarify.
Here's my take on this:
. What happens is clear: stack overflow during GC. Since the stack
space is always limited, one can always overflow it by
deliberately consing larger and larger objects.
. When stack overflow happens during GC, Emacs commits suicide,
because such fatal errors are not recoverable with the current
code.
. Making GC non-recursive is a large job, that will most probably
require significant changes in GC as a whole, not just in the
recursive mark step. If someone wants to work on that, they
surely don't need this bug as an inspiration.
IOW, this is a known limitation of the current GC implementation. So
I think we should mark this bug "wishlist" (or maybe even "wontfix"),
and leave it at that.
Any objections/comments/suggestions?
next prev parent reply other threads:[~2016-01-11 15:11 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-28 23:06 bug#2099: 23.0.60; `mark_object' with larger nested objects crashes Emacs Markus Triska
2011-09-11 21:08 ` Lars Magne Ingebrigtsen
2011-09-11 21:54 ` Andreas Schwab
2011-09-11 21:53 ` Lars Magne Ingebrigtsen
2011-09-11 23:47 ` Lars Magne Ingebrigtsen
2016-01-10 22:12 ` Alan J Third
2016-01-11 15:11 ` Eli Zaretskii [this message]
2016-01-11 17:49 ` Alan J Third
2016-01-11 19:10 ` markus.triska
2016-01-11 19:16 ` Eli Zaretskii
2016-01-11 19:57 ` markus.triska
2016-01-11 20:32 ` Alan J Third
2016-01-11 20:45 ` Eli Zaretskii
2016-01-11 20:32 ` Eli Zaretskii
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