Infinite loop in X-Server communication

[halfdog]

Binary package hint: fvwm

Not clear if problem lies within fvwm, xserver or libraries, so
I report it here first, perhaps someone can give hints where to
look or what to try next time.

Symptoms:

* 100% CPU-load, 70% in xserver, 30% in fvwm
* Mouse can move, but xterm stays highlighted, even when left (mouse follow focus not working)
* highlighted xterm: keyboard/graphics still working, command input possible
* xosview (not highlighted): graphics output works
* mouse cannot move across border to next virtual screen (fvwmpager)
* Mouse cursor icon is standard mozilla busy icon from mozilla running on other screen
* When mozilla is killed via shell, the cursor does not change, nor does mozilla window preview vanish from pager (not updated)

System:

# lsb_release -rd
Description: Ubuntu lucid (development branch)
Release: 10.04

ii fvwm 1:2.5.28.ds-3 F(?) Virtual Window Manager

# dpkg -l | grep xorg
ii xserver-xorg 1:7.5+3ubuntu1 the X.Org X server
ii xserver-xorg-core 2:1.7.6-1ubuntu1 Xorg X server - core server
ii xserver-xorg-input-all 1:7.5+3ubuntu1 the X.Org X server -- input driver metapacka
ii xserver-xorg-input-evdev 1:2.3.2-3ubuntu2 X.Org X server -- evdev input driver
ii xserver-xorg-input-mouse 1:1.5.0-1 X.Org X server -- mouse input driver
ii xserver-xorg-input-synaptics 1.2.0-3ubuntu2 Synaptics TouchPad driver for X.Org server
ii xserver-xorg-input-vmmouse 1:12.6.5-2ubuntu4 X.Org X server -- VMMouse input driver to us
ii xserver-xorg-input-wacom 1:0.10.3+20100109-1ubuntu3 X.Org X server -- Wacom input driver
ii xserver-xorg-video-vmware 1:10.16.9-1 X.Org X server -- VMware display driver

Loop description:

Attached debugger using ssh
gdb --pid [pid]

Stopped fvwm:

#0 0x008b8422 in __kernel_vsyscall ()
#1 0x00978b1b in poll () from /lib/tls/i686/cmov/libc.so.6
#2 0x00686d60 in ?? () from /usr/lib/libxcb.so.1
#3 0x006889b2 in xcb_wait_for_reply () from /usr/lib/libxcb.so.1
#4 0x00d80f96 in _XReply () from /usr/lib/libX11.so.6
#5 0x00d6e54d in XQueryPointer () from /usr/lib/libX11.so.6
#6 0x0806cfab in ?? ()

break __kernel_vsyscall

repeated continue/bt shows this:

#1 0x00978b1b in poll () from /lib/tls/i686/cmov/libc.so.6
#2 0x00686d60 in ?? () from /usr/lib/libxcb.so.1
#3 0x006889b2 in xcb_wait_for_reply () from /usr/lib/libxcb.so.1
#4 0x00d80f96 in _XReply () from /usr/lib/libX11.so.6
#5 0x00d6e54d in XQueryPointer () from /usr/lib/libX11.so.6
                  ^^^^^^^^^^^^

#0 0x008b8420 in __kernel_vsyscall ()
#1 0x00976dd3 in read () from /lib/tls/i686/cmov/libc.so.6
#2 0x00688bb0 in ?? () from /usr/lib/libxcb.so.1
#3 0x00686dfb in ?? () from /usr/lib/libxcb.so.1
#4 0x006889b2 in xcb_wait_for_reply () from /usr/lib/libxcb.so.1
#5 0x00d80f96 in _XReply () from /usr/lib/libX11.so.6
#6 0x00d6e54d in XQueryPointer () from /usr/lib/libX11.so.6

#0 0x008b8420 in __kernel_vsyscall ()
#1 0x00976dd3 in read () from /lib/tls/i686/cmov/libc.so.6
#2 0x00688bb0 in ?? () from /usr/lib/libxcb.so.1
#3 0x006891e8 in xcb_poll_for_event () from /usr/lib/libxcb.so.1
#4 0x00d80749 in ?? () from /usr/lib/libX11.so.6
#5 0x00d80a31 in ?? () from /usr/lib/libX11.so.6
#6 0x00d80fb6 in _XReply () from /usr/lib/libX11.so.6
#7 0x00d6e54d in XQueryPointer () from /usr/lib/libX11.so.6

#0 0x008b8420 in __kernel_vsyscall ()
#1 0x00950c80 in nanosleep () from /lib/tls/i686/cmov/libc.so.6
#2 0x0098041c in usleep () from /lib/tls/i686/cmov/libc.so.6
#3 0x0806cfbe in ?? ()
#4 0x08070949 in ?? ()
#5 0x0806cde9 in ?? ()
#6 0x0806d545 in ?? ()
#7 0x08091315 in ?? ()
#8 0x008cfbd6 in __libc_start_main () from /lib/tls/i686/cmov/libc.so.6

#0 0x008b8420 in __kernel_vsyscall ()
#1 0x00976dd3 in read () from /lib/tls/i686/cmov/libc.so.6
#2 0x00688bb0 in ?? () from /usr/lib/libxcb.so.1
#3 0x006891e8 in xcb_poll_for_event () from /usr/lib/libxcb.so.1
#4 0x00d80749 in ?? () from /usr/lib/libX11.so.6
#5 0x00d80a31 in ?? () from /usr/lib/libX11.so.6
#6 0x00d81356 in _XEventsQueued () from /usr/lib/libX11.so.6
#7 0x00d53499 in XCheckMaskEvent () from /usr/lib/libX11.so.6
                  ^^^^^^^^^^^^^^^
#8 0x080e7a16 in ?? ()
#9 0x0806cf5a in ?? ()
#10 0x08070949 in ?? ()
#11 0x0806cde9 in ?? ()
#12 0x0806d545 in ?? ()
#13 0x08091315 in ?? ()

#0 0x008b8420 in __kernel_vsyscall ()
#1 0x00978b1b in poll () from /lib/tls/i686/cmov/libc.so.6
#2 0x00686d60 in ?? () from /usr/lib/libxcb.so.1
#3 0x006872cb in ?? () from /usr/lib/libxcb.so.1
#4 0x00687667 in xcb_writev () from /usr/lib/libxcb.so.1
#5 0x00d80d79 in _XSend () from /usr/lib/libX11.so.6
#6 0x00d813d9 in _XFlush () from /usr/lib/libX11.so.6
#7 0x00d534af in XCheckMaskEvent () from /usr/lib/libX11.so.6
#8 0x080e7a16 in ?? ()
#9 0x0806cf5a in ?? ()
#10 0x08070949 in ?? ()
#11 0x0806cde9 in ?? ()
#12 0x0806d545 in ?? ()

#0 0x008b8420 in __kernel_vsyscall ()
#1 0x0097ea31 in writev () from /lib/tls/i686/cmov/libc.so.6
#2 0x00686e5b in ?? () from /usr/lib/libxcb.so.1
#3 0x006872cb in ?? () from /usr/lib/libxcb.so.1
#4 0x00687667 in xcb_writev () from /usr/lib/libxcb.so.1
#5 0x00d80d79 in _XSend () from /usr/lib/libX11.so.6
#6 0x00d813d9 in _XFlush () from /usr/lib/libX11.so.6
#7 0x00d534af in XCheckMaskEvent () from /usr/lib/libX11.so.6
#8 0x080e7a16 in ?? ()
#9 0x0806cf5a in ?? ()
#10 0x08070949 in ?? ()
#11 0x0806cde9 in ?? ()
#12 0x0806d545 in ?? ()

#0 0x008b8420 in __kernel_vsyscall ()
#1 0x00976dd3 in read () from /lib/tls/i686/cmov/libc.so.6
#2 0x00688bb0 in ?? () from /usr/lib/libxcb.so.1
#3 0x006891e8 in xcb_poll_for_event () from /usr/lib/libxcb.so.1
#4 0x00d80749 in ?? () from /usr/lib/libX11.so.6
#5 0x00d80a31 in ?? () from /usr/lib/libX11.so.6
#6 0x00d81356 in _XEventsQueued () from /usr/lib/libX11.so.6
#7 0x00d813e9 in _XFlush () from /usr/lib/libX11.so.6
#8 0x00d534af in XCheckMaskEvent () from /usr/lib/libX11.so.6
#9 0x080e7a16 in ?? ()
#10 0x0806cf5a in ?? ()
#11 0x08070949 in ?? ()
#12 0x0806cde9 in ?? ()
#13 0x0806d545 in ?? ()
#14 0x08091315 in ?? ()

#0 0x008b8420 in __kernel_vsyscall ()
#1 0x00978b1b in poll () from /lib/tls/i686/cmov/libc.so.6
#2 0x00686d60 in ?? () from /usr/lib/libxcb.so.1
#3 0x006872cb in ?? () from /usr/lib/libxcb.so.1
#4 0x00687667 in xcb_writev () from /usr/lib/libxcb.so.1
                  ^^^^^^^^^^
#5 0x00d80d79 in _XSend () from /usr/lib/libX11.so.6
#6 0x00d80f10 in _XReply () from /usr/lib/libX11.so.6
#7 0x00d6e54d in XQueryPointer () from /usr/lib/libX11.so.6
#8 0x0806cfab in ?? ()
#9 0x08070949 in ?? ()
#10 0x0806cde9 in ?? ()
#11 0x0806d545 in ?? ()
#12 0x08091315 in ?? ()
#13 0x008cfbd6 in __libc_

#0 0x008b8420 in __kernel_vsyscall ()
#1 0x0097ea31 in writev () from /lib/tls/i686/cmov/libc.so.6
#2 0x00686e5b in ?? () from /usr/lib/libxcb.so.1
#3 0x006872cb in ?? () from /usr/lib/libxcb.so.1
#4 0x00687667 in xcb_writev () from /usr/lib/libxcb.so.1
#5 0x00d80d79 in _XSend () from /usr/lib/libX11.so.6
#6 0x00d80f10 in _XReply () from /usr/lib/libX11.so.6
#7 0x00d6e54d in XQueryPointer () from /usr/lib/libX11.so.6
#8 0x0806cfab in ?? ()
#9 0x08070949 in ?? ()
#10 0x0806cde9 in ?? ()
#11 0x0806d545 in ?? ()
#12 0x08091315 in ?? ()
#13 0x008cfbd6 in __libc_start_main () from /lib/tls/i686/cmov/libc.so.6
#14 0x0804eb01 in ?? ()

#0 0x008b8420 in __kernel_vsyscall ()
#1 0x00978b1b in poll () from /lib/tls/i686/cmov/libc.so.6
#2 0x00686d60 in ?? () from /usr/lib/libxcb.so.1
#3 0x006889b2 in xcb_wait_for_reply () from /usr/lib/libxcb.so.1
#4 0x00d80f96 in _XReply () from /usr/lib/libX11.so.6
#5 0x00d6e54d in XQueryPointer () from /usr/lib/libX11.so.6
#6 0x0806cfab in ?? ()
#7 0x08070949 in ?? ()
#8 0x0806cde9 in ?? ()
#9 0x0806d545 in ?? ()
#10 0x08091315 in ?? ()
#11 0x008cfbd6 in __libc_start_main () from /lib/tls/i686/cmov/libc.so.6
#12 0x0804eb01 in ?? ()

----- loop seems to start again from beginning ---

[halfdog (halfdog)]

This issue might have been fixed now. Although I still use the software in the same way, I have not observed any problems since 2010-04-24. Before that, problems occurred all 1-3h when using X+fvwm2.

From my logs:

<p><b>201004241418 System upgrade:</b>
# apt-get dist-upgrade
Reading package lists...
Building dependency tree...
Reading state information...
The following packages will be upgraded:
  base-files busybox-initramfs initramfs-tools initramfs-tools-bin libc-bin
  libc-dev-bin libc6 libc6-dev libc6-i686 libglib2.0-0 libglib2.0-data
  libgphoto2-2 libgphoto2-port0 openoffice.org openoffice.org-base
  openoffice.org-base-core openoffice.org-calc openoffice.org-common
  openoffice.org-core openoffice.org-draw openoffice.org-emailmerge
  openoffice.org-filter-binfilter openoffice.org-filter-mobiledev
  openoffice.org-hyphenation-de openoffice.org-impress
  openoffice.org-java-common openoffice.org-math openoffice.org-officebean
  openoffice.org-report-builder-bin openoffice.org-style-galaxy
  openoffice.org-writer perl perl-base perl-modules python-uno ttf-opensymbol
  tzdata tzdata-java uno-libs3 ure xfonts-mathml xserver-common
  xserver-xorg-core xserver-xorg-input-vmmouse xserver-xorg-input-wacom
45 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 108MB of archives.

As you see: no fvwm but X update, so error might have been in X server code?