[debbugs-tracker] bug#34256: closed (27.0.50; Crash on draw_glyphs())

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Your message dated Mon, 04 Feb 2019 19:50:50 +0200
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and subject line Re: bug#34256: 27.0.50; Crash on draw_glyphs()
has caused the debbugs.gnu.org bug report #34256,
regarding 27.0.50; Crash on draw_glyphs()
to be marked as done.

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34256: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=34256
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--- Begin Message --- Subject: 27.0.50; Crash on draw_glyphs() Date: Wed, 30 Jan 2019 09:30:23 -0500

Hello,

I was working in an Org mode buffer and I got this crash on doing C-x v u (vc-revert).

Thread 1 "emacs" received signal SIGSEGV, Segmentation fault.
0x00000000004c6814 in x_draw_glyph_string ()
(gdb) bt
#0  0x00000000004c6814 in x_draw_glyph_string ()
#1  0x000000000045b394 in draw_glyphs ()
#2  0x0000000000460ec9 in x_write_glyphs ()
#3  0x000000000041eb02 in update_window_line ()
#4  0x0000000000420737 in update_window ()
#5  0x000000000042209a in update_window_tree ()
#6  0x00000000004220ab in update_window_tree ()
#7  0x000000000042445d in update_frame ()
#8  0x000000000045831f in redisplay_internal ()
#9  0x00000000004fc2b3 in read_char ()
#10 0x00000000004feccc in read_key_sequence ()
#11 0x000000000050168d in read_key_sequence_vs ()
#12 0x000000000056bcef in Ffuncall ()
#13 0x00000000005a4d73 in exec_byte_code ()
#14 0x000000000056bc6f in Ffuncall ()
#15 0x00000000005a4d73 in exec_byte_code ()
#16 0x000000000056bc6f in Ffuncall ()
#17 0x00000000005a4d73 in exec_byte_code ()
#18 0x000000000056bc6f in Ffuncall ()
#19 0x0000000000568700 in Ffuncall_interactively ()
#20 0x000000000056bcef in Ffuncall ()
#21 0x000000000056bf6d in Fapply ()
#22 0x0000000000569d8a in Fcall_interactively ()
#23 0x000000000056bcef in Ffuncall ()
#24 0x00000000005a4d73 in exec_byte_code ()
#25 0x000000000056bc6f in Ffuncall ()
#26 0x000000000056bdaa in call1 ()
#27 0x0000000000500630 in command_loop_1 ()
#28 0x000000000056af3e in internal_condition_case ()
#29 0x00000000004f2a1c in command_loop_2 ()
#30 0x000000000056aead in internal_catch ()
#31 0x00000000004f29c4 in command_loop ()
#32 0x00000000004f75e6 in recursive_edit_1 ()
#33 0x00000000004f7904 in Frecursive_edit ()
#34 0x00000000004f1d13 in main ()

Lisp Backtrace:
No symbol "CHECK_LISP_OBJECT_TYPE" in current context.

Note: I am using Emacs built using the harfbuzz branch but I don't know if this is related to that.

I have the gdb session open; let me know how to get more debug info for you.

Thank you.

In GNU Emacs 27.0.50 (build 11, x86_64-pc-linux-gnu, GTK+ Version 2.24.23)
 of 2019-01-28 built on kmodi-lx01.cld.analog.com
Repository revision: 137b65a9b0a4118adda50f34375b4960701542e9
Repository branch: master
Windowing system distributor 'Open Text', version 11.0.11505
System Description: Red Hat Enterprise Linux Workstation release 6.8 (Santiago)

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.

Configured using:
 'configure --with-modules
 --prefix=/home/kmodi/usr_local/apps/6/emacs/master
 '--program-transform-name=s/^ctags$/ctags_emacs/' --with-harfbuzz
 'CPPFLAGS=-I/home/kmodi/stowed/include
 -I/home/kmodi/usr_local/6/include -I/usr/include/freetype2
 -I/usr/include' 'CFLAGS=-O2 -march=native'
 'LDFLAGS=-L/home/kmodi/stowed/lib -L/home/kmodi/stowed/lib64
 -L/home/kmodi/usr_local/6/lib -L/home/kmodi/usr_local/6/lib64'
 PKG_CONFIG_PATH=/home/kmodi/usr_local/6/lib/pkgconfig:/home/kmodi/usr_local/6/lib64/pkgconfig:/cad/adi/apps/gnu/linux/x86_64/6/lib/pkgconfig:/cad/adi/apps/gnu/linux/x86_64/6/lib64/pkgconfig:/home/kmodi/stowed/lib/pkgconfig:/usr/lib/pkgconfig:/usr/lib64/pkgconfig:/usr/share/pkgconfig:/lib/pkgconfig:/lib64/pkgconfig'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS GLIB
NOTIFY INOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF
XFT ZLIB TOOLKIT_SCROLL_BARS GTK2 X11 XDBE XIM MODULES THREADS
CANNOT_DUMP GMP

--
Kaushal Modi

--- End Message ---

> --- Begin Message ---
>
>
>
> Subject: 
>
> Re: bug#34256: 27.0.50; Crash on draw_glyphs()
>
>
>
>
> Date: 
>
> Mon, 04 Feb 2019 19:50:50 +0200
>
>
>
>
> > From: Kaushal Modi <address@hidden>
> > Date: Mon, 4 Feb 2019 11:03:37 -0500
> > Cc: address@hidden
> > 
> > Thanks for the patch!
> > 
> > I couldn't apply the patch, so had to apply it manually.
> > 
> > But it works!
>
> Thanks, I've now pushed it to the master branch.
>
> > I am looking forward to understand in plain terms what this fix did. 
>
> What happened was that while the display engine was redisplaying the
> buffer, font-lock was called to fontify some part of the buffer, and
> that activated Org mode (because the buffer displayed diffs of an Org
> file, I presume?), and Org mode explicitly clears the image cache of
> the frame for some reason I couldn't fathom.  So an inline image that
> was ready to be displayed got removed and freed from under the feet of
> the display engine, and when the time came to actually display it,
> there was nothing to display...
>
> The fix is to inhibit clearing of a frame's image cache until after
> the frame has been updated by the display engine.
>
> Thanks for helping me track this bug.
>
>
> --- End Message ---