3.1-rcX (8,9,10): kernel does not validate swapfile on disk(?) -WAS: vnc4server 4.1.1+X4.3.0-3 crashing under normal use

[Justin Piszcz]

Package: vnc4server
Version: 4.1.1+X4.3.0-3
Architecture: amd64 (x86-64)
Kernel: 3.0-rc9

Current theory--

(Debian, ) You can close the bug report, my .swapfile was corrupted it 
appears! When I ran swapoff -a and re-launched VNC it did not crash 
anymore, unbelievable, I am also cc'ing the kernel mailing list on this one,
how come the kernel does not ALARM or WARN or BUG() when there is a problem 
with the swapfile, is there no validation?

I was testing many 3.1.0-rcX kernels (some of them crashed my machine) and 
it must have corrupted that file.  The weird part is it only seemed to 
(mainly) affect VNC, I also saw a coredump with xfs_db (randomly) and a 
memtest86+ showed ok after 1-2 passes.

Of course it was the last thing I decided to rule out and that was it-- it 
appears, so far it has not crashed in over an hour, whereas it would crash 
immediately in the past, over and over for several days so I stopped using 
VNC until I had time to look into this problem further.

Very interesting and putting this out there incase anyone else sees this 
problem in the future, maybe it will help someone else.  But I wish the 
kernel would alarm if there were some problem with the swapfile..  Even 
when swap was not in use, the presence of the [bad] file would cause vnc 
to coredump quickly (after launching chrome/thunderbird/etc)  After a 
swapoff -a -- all problems, gone. All is back to normal now.

I waited a few hours before sending this, still no problems/errors, very 
interesting, will update if any future coredumps, but none yet..

Justin.


> Problem: About 1-2 weeks ago (I apt-get dist-upgrade regularly), VNC server
> began crashing, e.g. if you launch thunderbird/google chrome or other 
> windows, the VNC server crashes.
>
> May be related to:
> http://old.nabble.com/Bug-424860%3A-eclipse-randomly-crashes-(VNC)-X-server-p11945956.html
> http://forums.fedoraforum.org/showthread.php?t=246145
>
> Example:
>
> $ strace -o /tmp/out -f Xvnc -geometry 1920x1200 -depth 24 -rfbauth 
> ~/.vnc/passwd :1
>
> Xvnc Free Edition 4.1.1 - built Mar 10 2010 22:35:30
> Copyright (C) 2002-2005 RealVNC Ltd.
> See http://www.realvnc.com for information on VNC.
> Underlying X server release 40300000, The XFree86 Project, Inc
>
>
> Sat Oct 22 19:38:49 2011
> vncext:      VNC extension running!
> vncext:      Listening for VNC connections on port 5901
> vncext:      created VNC server for screen 0
> error opening security policy file /etc/X11/xserver/SecurityPolicy
> Could not init font path element /usr/share/fonts/X11/Speedo/, removing from 
> list!
> Could not init font path element /usr/share/fonts/X11/CID/, removing from 
> list!
>
> Sat Oct 22 19:38:51 2011
> Connections: accepted: 0.0.0.0::53214
> SConnection: Client needs protocol version 3.8
> SConnection: Client requests security type VncAuth(2)
>
> Sat Oct 22 19:38:53 2011
> VNCSConnST:  Server default pixel format depth 24 (32bpp) little-endian 
> bgr888
> VNCSConnST:  Client pixel format depth 8 (8bpp) rgb max 3,3,3 shift 4,2,0
> VNCSConnST:  Client pixel format depth 24 (32bpp) little-endian rgb888
> Segmentation fault (core dumped)
>
> --
>
> Core backtrace:
>
> $ gdb /usr/bin/Xvnc ./core.Xvnc.26042
> GNU gdb (GDB) 7.3-debian
> Copyright (C) 2011 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
> and "show warranty" for details.
> This GDB was configured as "x86_64-linux-gnu".
> For bug reporting instructions, please see:
> <http://www.gnu.org/software/gdb/bugs/>...
> Reading symbols from /usr/bin/Xvnc...(no debugging symbols found)...done.
> [New LWP 26042]
>
> warning: Can't read pathname for load map: Input/output error.
> Core was generated by `Xvnc -geometry 1920x1200 -depth 24 -rfbauth 
> /home/user/.vnc/passwd :1'.
> Program terminated with signal 11, Segmentation fault.
> #0  0x00000000004cbed4 in ?? ()
> (gdb) bt
> #0  0x00000000004cbed4 in ?? ()
> #1  0x00000000004dd577 in ?? ()
> #2  0x00000000005832a2 in ?? ()
> #3  0x00000000005834ff in ?? ()
> #4  0x0000000000426d90 in ?? ()
> #5  0x000000000040be86 in ?? ()
> #6  0x00007f070be96ead in __libc_start_main ()
>   from /lib/x86_64-linux-gnu/libc.so.6
> #7  0x0000000000409259 in ?? ()
> #8  0x00007fff22a53788 in ?? ()
> #9  0x000000000000001c in ?? ()
> #10 0x0000000000000008 in ?? ()
> #11 0x00007fff22a54b2e in ?? ()
> #12 0x00007fff22a54b33 in ?? ()
> #13 0x00007fff22a54b3d in ?? ()
> #14 0x00007fff22a54b47 in ?? ()
> #15 0x00007fff22a54b4e in ?? ()
> #16 0x00007fff22a54b51 in ?? ()
> #17 0x00007fff22a54b5a in ?? ()
> #18 0x00007fff22a54b70 in ?? ()
> #19 0x0000000000000000 in ?? ()
> (gdb)
>
> --
>
>
> Strace output: (4M)
> http://home.comcast.net/~jpiszcz/20111022/vnc-strace.out
>
> From the $HOME/.vnc/*log file:
>
> (xfdesktop:5201): Wnck-CRITICAL **: wnck_workspace_get_number: assertion 
> `WNCK_IS_WORKSPACE (space)' failed
> libpager-Message: Setting the pager rows returned false. Maybe the setting is 
> not applied.
>
> Sat Oct 22 14:26:14 2011
> Connections: accepted: 0.0.0.0::49493
> SConnection: Client needs protocol version 3.8
> SConnection: Client requests security type VncAuth(2)
>
> Sat Oct 22 14:26:15 2011
> VNCSConnST:  Server default pixel format depth 24 (32bpp) little-endian 
> bgr888
> VNCSConnST:  Client pixel format depth 8 (8bpp) rgb max 3,3,3 shift 4,2,0
>
> Sat Oct 22 14:26:16 2011
> VNCSConnST:  Client pixel format depth 24 (32bpp) little-endian rgb888
> Gkr-Message: secret service operation failed: The name 
> org.freedesktop.secrets was not provided by any .service files
> XIO:  fatal IO error 11 (Resource temporarily unavailable) on X server ":1"
>      after 143 requests (143 known processed) with 0 events remaining.
> xfce4-panel: Fatal IO error 11 (Resource temporarily unavailable) on X server 
> :1.0.
> xfdesktop: Fatal IO error 11 (Resource temporarily unavailable) on X server 
> :1.0.
> [31476:31476:297527619035:ERROR:chrome_browser_main_x11.cc(57)] X IO Error 
> detected
> xfwm4: Fatal IO error 11 (Resource temporarily unavailable) on X server :1.0.
> xfce4-session: Fatal IO error 11 (Resource temporarily unavailable) on X 
> server :1.
> XIO:  fatal IO error 11 (Resource temporarily unavailable) on X server ":1"
>      after 64951 requests (64951 known processed) with 0 events remaining.
> Thunar: Fatal IO error 11 (Resource temporarily unavailable) on X server 
> :1.0.
> wrapper: Fatal IO error 11 (Resource temporarily unavailable) on X server 
> :1.0.
> running 'ssh-agent -s -k'
> xfsettingsd: Fatal IO error 11 (Resource temporarily unavailable) on X server 
> :1.
> unset SSH_AUTH_SOCK;
> unset SSH_AGENT_PID;
> echo Agent pid 5181 killed;
>
>
> --
>
> Thoughts?
>
> Justin.
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