bug#11351: 24.1.50; marker does not point anywhere

[Sam Steingold]

In GNU Emacs 24.1.50.2 (x86_64-unknown-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2012-04-25 on t520sds
Bzr revision: 108032 sdl.web@gmail.com-20120425152319-6spihz4warse7g3v
Windowing system distributor `The X.Org Foundation', version 11.0.11004000
Configured using:
 `configure '--with-wide-int''

every now and then emacs falls into a catatonic trance.
gdb says:

(gdb) where
#0  0x00007ffff4182613 in select () from /lib/x86_64-linux-gnu/libc.so.6
#1  0x00000000004b89c4 in XTflash (f=0xf21a40) at 
/home/sds/src/emacs/trunk/src/xterm.c:3165
#2  XTring_bell (f=0xf21a40) at /home/sds/src/emacs/trunk/src/xterm.c:3236
#3  0x00000000004f5718 in cmd_error_internal (data=72641286, 
context=0x7fffffffb1d0 "") at /home/sds/src/emacs/trunk/src/keyboard.c:1103
#4  0x00000000004f5896 in cmd_error (data=72641286) at 
/home/sds/src/emacs/trunk/src/keyboard.c:1036
#5  0x00000000005667c9 in internal_condition_case (bfun=0x5009f0 
<command_loop_1>, handlers=12019090, hfun=0x4f5780 <cmd_error>)
    at /home/sds/src/emacs/trunk/src/eval.c:1438
#6  0x00000000004f3bee in command_loop_2 (ignore=<optimized out>) at 
/home/sds/src/emacs/trunk/src/keyboard.c:1160
#7  0x0000000000566678 in internal_catch (tag=Cannot access memory at address 
0xffffffffffffffe0
) at /home/sds/src/emacs/trunk/src/eval.c:1205
#8  0x00000000004f51cf in command_loop () at 
/home/sds/src/emacs/trunk/src/keyboard.c:1125
#9  recursive_edit_1 () at /home/sds/src/emacs/trunk/src/keyboard.c:759
#10 0x00000000004f558c in Frecursive_edit () at 
/home/sds/src/emacs/trunk/src/keyboard.c:823
#11 0x00000000005684fb in Ffuncall (nargs=<optimized out>, args=0x7fffffffb5c0) 
at /home/sds/src/emacs/trunk/src/eval.c:2932
#12 0x00000000005a0b56 in exec_byte_code (bytestr=<optimized out>, 
vector=<optimized out>, maxdepth=<optimized out>, args_template=<optimized 
out>, 
    nargs=<optimized out>, args=<optimized out>) at 
/home/sds/src/emacs/trunk/src/bytecode.c:785
#13 0x0000000000567fa1 in funcall_lambda (fun=30331573, nargs=<optimized out>, 
arg_vector=0x7fffffffb858)
    at /home/sds/src/emacs/trunk/src/eval.c:3166
#14 0x000000000056831b in Ffuncall (nargs=3, args=0x7fffffffb850) at 
/home/sds/src/emacs/trunk/src/eval.c:2996
#15 0x00000000005693b7 in Fapply (nargs=<optimized out>, args=0x7fffffffb910) 
at /home/sds/src/emacs/trunk/src/eval.c:2440
#16 0x0000000000568870 in apply1 (fn=12088930, arg=<optimized out>) at 
/home/sds/src/emacs/trunk/src/eval.c:2678
#17 0x0000000000568a21 in call_debugger (arg=57847750) at 
/home/sds/src/emacs/trunk/src/eval.c:227
#18 0x0000000000568e86 in maybe_call_debugger (data=57847862, sig=12019090, 
conditions=8632246) at /home/sds/src/emacs/trunk/src/eval.c:1863
#19 Fsignal (error_symbol=12019090, data=57847862) at 
/home/sds/src/emacs/trunk/src/eval.c:1684
#20 0x0000000000569069 in xsignal (error_symbol=<optimized out>, 
data=<optimized out>) at /home/sds/src/emacs/trunk/src/eval.c:1719
#21 0x0000000000569b37 in xsignal1 (error_symbol=12019090, arg=<optimized out>) 
at /home/sds/src/emacs/trunk/src/eval.c:1734
#22 0x0000000000569bbc in verror (m=<optimized out>, ap=<optimized out>) at 
/home/sds/src/emacs/trunk/src/eval.c:1932
#23 0x0000000000569c4c in error (m=<optimized out>) at 
/home/sds/src/emacs/trunk/src/eval.c:1944
#24 0x000000000051dcc4 in marker_position (marker=<optimized out>) at 
/home/sds/src/emacs/trunk/src/marker.c:777
#25 0x0000000000514667 in overlays_at (pos=77003, extend=0, 
vec_ptr=0x7fffffffccd8, len_ptr=0x7fffffffcce0, next_ptr=0x0, prev_ptr=0x0, 
change_req=0)
    at /home/sds/src/emacs/trunk/src/buffer.c:2541
#26 0x00000000005bc60f in get_char_property_and_overlay (position=308012, 
prop=12156402, object=43556693, overlay=0x0)
    at /home/sds/src/emacs/trunk/src/textprop.c:626
#27 0x00000000005b9756 in get_local_map (position=<optimized out>, 
buffer=0x2989f50, type=12156402) at 
/home/sds/src/emacs/trunk/src/intervals.c:2306
#28 0x00000000004febe7 in read_key_sequence (keybuf=0x7fffffffcf40, 
prompt=11966850, dont_downcase_last=0, can_return_switch_frame=1, 
    fix_current_buffer=1, bufsize=30) at 
/home/sds/src/emacs/trunk/src/keyboard.c:9147
#29 0x0000000000500bc5 in command_loop_1 () at 
/home/sds/src/emacs/trunk/src/keyboard.c:1449
#30 0x0000000000566796 in internal_condition_case (bfun=0x5009f0 
<command_loop_1>, handlers=12019090, hfun=0x4f5780 <cmd_error>)
---Type <return> to continue, or q <return> to quit---
    at /home/sds/src/emacs/trunk/src/eval.c:1448
#31 0x00000000004f3bee in command_loop_2 (ignore=<optimized out>) at 
/home/sds/src/emacs/trunk/src/keyboard.c:1160
#32 0x0000000000566678 in internal_catch (tag=Cannot access memory at address 
0xffffffffffffffe0
) at /home/sds/src/emacs/trunk/src/eval.c:1205
#33 0x00000000004f5257 in command_loop () at 
/home/sds/src/emacs/trunk/src/keyboard.c:1139
#34 recursive_edit_1 () at /home/sds/src/emacs/trunk/src/keyboard.c:759
#35 0x00000000004f558c in Frecursive_edit () at 
/home/sds/src/emacs/trunk/src/keyboard.c:823
#36 0x000000000040fe8d in main (argc=1, argv=<optimized out>) at 
/home/sds/src/emacs/trunk/src/emacs.c:1711

Lisp Backtrace:
"recursive-edit" (0xffffb5c8)
"debug" (0xffffb858)

emacs displays the *Backtrace* buffer with a single line:

debugger entered--lisp error: (error "Marker does not point anywhere")

and neither C-g not C-] can get me out.
moreover, I have visible bell on, so the top and bootom lines are in
reverse video, i.e., emacs is constantly sounding the bell.
(I am writing this in a separate emacs session)
I already had to kill emacs a few times times before; this is very
annoying.
this appears to have been caused by a recent change (last 2 weeks?).


 
-- 
Sam Steingold (http://sds.podval.org/) on Ubuntu 11.10 (oneiric) X 11.0.11004000
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