bug#47244: 28.0.50; SIGSEGV in long-runnning Emacs

[Michael Welsh Duggan]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Michael Welsh Duggan <mwd@cert.org>
>> Cc: Michael Welsh Duggan <mwd@md5i.com>, "rudalics@gmx.at"
>>  <rudalics@gmx.at>,
>>         "schwab@linux-m68k.org" <schwab@linux-m68k.org>,
>>         "47244@debbugs.gnu.org" <47244@debbugs.gnu.org>
>> Date: Mon, 29 Mar 2021 10:06:43 -0400
>> 
>> #0  set_buffer_internal_2 (b=0x5555578f43d8) at 
>> ../../master/src/buffer.c:2155
>>         old_buf = 0x555555593480 <_start>
>>         tail = XIL(0)
>> #1  0x0000555555713f28 in set_buffer_internal_1 (b=0x1)
>>     at ../../master/src/buffer.c:2141
>> #2  0x00005555556e4ec6 in set_buffer_internal (b=0x5555578f43d8)
>>     at ../../master/src/buffer.h:1184
>> #3  0x00005555556e6b21 in command_loop_1 () at 
>> ../../master/src/keyboard.c:1289
>>         cmd = XIL(0x7fffffffde10)
>>         keybuf = 
>>           {XIL(0), XIL(0x7ffff2c27c1d), XIL(0x555555765cd4), XIL(0x11cf6b0), 
>> XIL(0x7fffffffdd70), XIL(0x55555579e20b), XIL(0x11cf6b0), 
>> XIL(0x7ffff257e4c4), XIL(0x555559de7123), XIL(0x7ffff2c27c1d), 
>> XIL(0x7ffff2c27c1d), XIL(0x555559de7123), XIL(0x7ffff257e4c4), 
>> XIL(0x11cf6b0), XIL(0), XIL(0), XIL(0x555555cc5f80), XIL(0), XIL(0), 
>> XIL(0x7fffffffdd70), XIL(0x5555556e3c73), XIL(0xffffddc0), 
>> XIL(0x555555cc5f80), XIL(0), XIL(0), XIL(0x7fffffffdda0), 
>> XIL(0x555555797d03), make_fixnum(0), XIL(0x7fffffffdde0), 
>> XIL(0x55555579b3f4)}
>>         i = 1
>>         prev_modiff = 0
>>         prev_buffer = 0x0
>>         already_adjusted = false
>
> OK, we are switching to the selected window's buffer, and that buffer
> was deleted.  We still don't understand how this happens.  Martin, any
> ideas?
>
> Please show the results of these commands:
>
>  (gdb) p current_buffer->name_
>  (gdb) xstring
>  (gdb) frame 3
>  (gdb) p cmd
>  (gdb) xtype

(gdb) p current_buffer->name_
$4 = XIL(0x5555573519f4)
(gdb) xstring
$5 = (struct Lisp_String *) 0x5555573519f0
" *nntpd*"
(gdb) frame 3
#3  0x00005555556e6b21 in command_loop_1 () at ../../master/src/keyboard.c:1289
1289          set_buffer_internal (XBUFFER (XWINDOW 
(selected_window)->contents));
(gdb) p cmd
$6 = XIL(0x7fffffffde10)
(gdb) xtype
Lisp_Symbol

I add also the following:

(gdb) p cmd
$7 = XIL(0x7fffffffde10)
(gdb) xsymbol
$8 = (struct Lisp_Symbol *) 0xd55555cc3d90
Cannot access memory at address 0xd55555cc3d98

-- 
Michael Welsh Duggan
(mwd@cert.org)