64-bit emacs crashes a lot

[Ken Brown]

On 8/5/2013 11:29 AM, Ryan Johnson wrote:
> On 05/08/2013 11:00 AM, Ken Brown wrote:
>> On 8/3/2013 3:05 PM, Ryan Johnson wrote:
>>> On 02/08/2013 8:07 AM, Ryan Johnson wrote:
>>>> On 02/08/2013 7:04 AM, Ken Brown wrote:
>>>>> On 8/2/2013 4:02 AM, Corinna Vinschen wrote:
>>>>>> On Aug  1 22:46, Ryan Johnson wrote:
>>>>>>> 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.
>>>>>
>>>>> Could this be BLODA?  Ryan, I noticed that you wrote in a different
>>>>> thread, "I recently migrated to 64-bit cygwin...and so far have not
>>>>> had to disable Windows Defender; the latter was a recurring source of
>>>>> trouble for my previous 32-bit cygwin install on Win7/64."
>>>> This would be a whole new level of nasty from a BLODA... I thought
>>>> they only interfered with fork()?
>>>>
>>>> However, this *is* Windows Defender we're talking about... service
>>>> disabled and all cygwin processes restarted. I'll let you know in a
>>>> day or so if the crashes go away.
>>> Rats. I just had another crash, the "Fatal error 6" variety. Windows
>>> Defender has not turned itself back on (it's been known to do that), and
>>> a scan of the BLODA list didn't match anything else on my system.
>>>
>>> So I don't think it's BLODA...
>>>
>>> Ideas?
>>
>> Not really, other than the obvious: (a) Find a reproducible way of
>> making emacs-nox crash.  (b) Catch the crash in gdb by setting a
>> suitable break point.
> I've had no luck with (a), but the latest version of gdb forwards
> signals properly (thanks cgf!), so I've got it watching in the
> background for anything to go wrong. If it's really a memory overwrite,
> though, the stack trace is unlikely to give much insight into root causes.

I had a couple of additional thoughts.  First, have you tried `emacs -Q' 
to make sure there's nothing in your .emacs that triggers the bug?  In 
the same vein, you might try not using the mouse, in case the bug has 
something to do with the way emacs/mintty handle mouse movements when 
emacs is running in non-GUI mode.

Second, would you be willing to try emacs-w32 and/or emacs-X11 to see if 
you have the same problem?  It might help narrow down the search if we 
knew that the bug only occurs with emacs-nox.

Ken


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