bug#21337: 25.0.50; inotify error message

[Eli Zaretskii <eliz@gnu.org>]

> From: Robert Pluim <rpluim@gmail.com>
> Cc: 21337@debbugs.gnu.org
> Date: Mon, 24 Aug 2015 18:51:38 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >>  '(dired-auto-revert-buffer (quote dired-directory-changed-p))
> >>  '(global-auto-revert-mode t)
> >>  '(global-auto-revert-non-file-buffers t)
> >> 
> >> although disabling those 3 makes no difference to the behaviour.
> >
> > Then I guess the next step is to set debug-on-error non-nil and show
> > the backtrace, so that we see what Lisp code errors out.
> >
> 
> I hadn't considered that, however it's not very enlightening:
> 
> Debugger entered--Lisp error: (file-notify-error "Error while trying to read file system events")
> 
> That error is coming from the inotify_callback function. From gdb the
> c-backtrace is:
> 
> #0  inotify_callback (fd=16, _=<optimized out>) at inotify.c:139
> #1  0x000000000059e3a0 in wait_reading_process_output (time_limit=<optimized out>, nsecs=<optimized out>, read_kbd=-1, 
>     do_display=true, wait_for_cell=0, wait_proc=0x0, just_wait_proc=0) at process.c:5085
> #2  0x0000000000422672 in sit_for (timeout=30, reading=112, display_option=0) at dispnew.c:5756
> #3  0x00000000004fa6dd in read_char (commandflag=0, commandflag@entry=1, map=13674864, map@entry=99582755, prev_event=-11, 
>     used_mouse_menu=0xfffffffffffffea8, used_mouse_menu@entry=0x7fffffffd7db, end_time=0xd0a990, end_time@entry=0x0)
>     at keyboard.c:2786
> #4  0x00000000004fb469 in read_key_sequence (keybuf=keybuf@entry=0x7fffffffd8b0, prompt=prompt@entry=0, 
>     dont_downcase_last=dont_downcase_last@entry=false, can_return_switch_frame=can_return_switch_frame@entry=true, 
>     fix_current_buffer=fix_current_buffer@entry=true, prevent_redisplay=prevent_redisplay@entry=false, bufsize=30) at keyboard.c:9188
> #5  0x00000000004fd171 in command_loop_1 () at keyboard.c:1406
> #6  0x000000000055fbd7 in internal_condition_case (bfun=bfun@entry=0x4fcf30 <command_loop_1>, handlers=handlers@entry=18912, 
>     hfun=hfun@entry=0x4f3a30 <cmd_error>) at eval.c:1356
> #7  0x00000000004ef00c in command_loop_2 (ignore=ignore@entry=0) at keyboard.c:1138
> #8  0x000000000055fab3 in internal_catch (tag=tag@entry=45168, func=func@entry=0x4eeff0 <command_loop_2>, arg=arg@entry=0)
>     at eval.c:1116
> #9  0x00000000004eefc9 in command_loop () at keyboard.c:1117
> #10 0x00000000004f363b in recursive_edit_1 () at keyboard.c:723
> #11 0x00000000004f3960 in Frecursive_edit () at keyboard.c:794
> #12 0x00000000004187d6 in main (argc=1, argv=0x7fffffffdc38) at emacs.c:1629

Strange.  Does auto-revert-mode work in "emacs -Q"?  Do the related
tests in the test suite pass?

Can you use strace to see what error is that and what directory is
being watched?