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Re: 64-bit emacs crashes a lot


On Aug  1 22:46, Ryan Johnson wrote:
> On 26/07/2013 11:32 PM, Ryan Johnson wrote:
> >On 26/07/2013 10:50 PM, Ken Brown wrote:
> >>On 7/26/2013 8:32 PM, Ryan Johnson wrote:
> >>>Hi all,
> >>>
> >>>Running 64-bit cygwin 1.7.22(0.268/5/3), with emacs-nox 24.3-4 inside
> >>>mintty 1.2-beta1-1, I keep getting seg faults and "Fatal error
> >>>6: Aborted"
> >
> >>>It happens at strange times, invariably during I/O of some kind (either
> >>>keyboard input or output from some compilation window); I don't get the
> >>>impression it's fork-related. I don't know how to get a backtrace from
> >>>emacs, given the way any exception or signal always loses the
> >>>"userland"
> >>>stack (suggestions welcome).
> >>>
> >>>Anyone else seeing this?
> >>
> >>This doesn't really answer your question since I don't use
> >>emacs-nox, but I've been running 64-bit emacs-X11 and finding it
> >>very stable.  I typically keep it running for several days at a
> >>time.
> >>
> >>You say you don't know how to get a backtrace from emacs.  I
> >>assume you've installed emacs-debuginfo and run emacs under gdb.
> >>Are you saying you can never get a backtrace after it crashes?
> >I do have the emacs-debuginfo. I meant that the stack dump didn't
> >have any emacs frames in it (they were all cygwin1.dll), and my
> >experience with cygwin/gdb is that once you've taken a signal or
> >exception you lose the cygwin stack and just see a bunch of
> >threads mucking around in various low-level Windows dlls.
> >
> >I have tried attaching gdb to emacs and setting a breakpoint on
> >abort(), but it didn't catch anything yet. I'm also hampered by
> >gdb constantly getting confused, breaking partway into emacs, and
> >having to detach/reattach it. I've started a new thread for that
> >issue.
> 
> Here's a new one... I started a compilation, but before it actually
> invoked the command it started pegging the CPU. After ^G^G^G, it
> crashed with the following:
> >Auto-save? (y or n) y
> >      0 [main] emacs 5076 C:\cygwin64\bin\emacs-nox.exe: *** fatal
> >error - Internal error: TP_NUM_W_BUFS too small 2268032 >= 10.

That looks like a memory overwrite.  2268032 is 0x229b80, which looks
suspiciously like a stack address.  And the overwritten value is on the
stack, too, well within the cygwin TLS area.  If *this* value gets
overwritten, the TLS is probbaly totally hosed at this point.  There's
just no way to infer the culprit from this limited info.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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