I've been seeing this problem also, abeit rather infrequently ( about once every 1-2 months), 
with all Ubuntu 14.04.1 kernels issued via updates since July 2014 .

This is on my machine at work which is left on all the time and only reboots when a new kernel is installed .

Machine:
8 core Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz

RAM: 16G

Current kernel :  3.13.0-45-lowlatency
Video Card:
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Cedar GL [FirePro 2270]

I removed "radeon" from the module blacklist so it gets installed instead of the broken fglrx drivers whose
user-space support programs and libraries seem suited to little other than generating core-dumps.

I have a dual monitor setup with xorg.conf settings:

Section "Monitor"
        Identifier  "Monitor0"
        Option      "DPMS" "true"
        Option      "Primary" "true"
        Option      "LeftOf"   "DVI-1"
        Modeline    "1920x1080@60.0"    148.50          1920 2008 2052 2200     1080 1084 1089 1125     +hsync +vsync
EndSection

Section "Monitor"
        Identifier  "Monitor1"
        Option      "DPMS" "true"
        Option      "RightOf"   "DVI-0"
        ModeLine    "1600x1200@60.0"    162.00          1600 1664 1856 2160     1200 1201 1204 1250     +hsync +vsync
EndSection



When the problem happens, the video card is left frozen displaying the last frames the X server emitted
(usually from the xscreensaver program).

I am able to SSH in to the host (networking still works, so the kernel is not totally locked up),  but 
attempts to kill the Xorg X-server fail,  and the console does not respond to <CTRL>+<ALT>+<F[1...7]>
"VT Switch" keystrokes.  The only thing I can do in this situation is SSH in to the machine and poweroff .

Before powering off, I did :
 $ dmesg -c > video_lockup.log
And I see these messages in the dmesg log :
[56089.032100] radeon 0000:01:00.0: GPU lockup CP stall for more than 10000msec
[56089.032112] radeon 0000:01:00.0: GPU lockup (waiting for 0x0000000000000004 last fence id 0x0000000000000002 on ring 5)
[56089.032119] [drm:uvd_v1_0_ib_test] *ERROR* radeon: fence wait failed (-35).

I was unable to kill the Xorg server with 'kill -TERM' .
I generated gcore file from the Xorg server (from xserver-xorg-1:7.7+1ubuntu8):
Core was generated by `/usr/bin/X'.
#0  0x00007f4c06ed2414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
(gdb) t a a bt

Thread 2 (Thread 0x7f4c07d879c0 (LWP 1793)):
#0  0x00007f4c059d5ec7 in ioctl () from /lib/x86_64-linux-gnu/libc.so.6
#1  0x00007f4c06cbd3a4 in drmIoctl () from /usr/lib/x86_64-linux-gnu/libdrm.so.2
#2  0x00007f4c06cbf6bf in drmCommandWriteRead () from /usr/lib/x86_64-linux-gnu/libdrm.so.2
#3  0x00007f4c01820c83 in ?? () from /usr/lib/x86_64-linux-gnu/libdrm_radeon.so.1
#4  0x00007f4c01a77e88 in ?? () from /usr/lib/xorg/modules/drivers/radeon_drv.so
#5  0x00007f4c01a4a0f7 in ?? () from /usr/lib/xorg/modules/drivers/radeon_drv.so
#6  0x00007f4c013d1835 in ?? () from /usr/lib/xorg/modules/libexa.so
#7  0x00007f4c013d1a78 in ?? () from /usr/lib/xorg/modules/libexa.so
#8  0x00007f4c013d3323 in ?? () from /usr/lib/xorg/modules/libexa.so
#9  0x00007f4c013d3c9b in ?? () from /usr/lib/xorg/modules/libexa.so
#10 0x00007f4c07f52b7d in miCopyRegion ()
#11 0x00007f4c07f53106 in miDoCopy ()
#12 0x00007f4c013d2326 in ?? () from /usr/lib/xorg/modules/libexa.so
#13 0x00007f4c07eff838 in ?? ()
#14 0x00007f4c07eac0f8 in ?? ()
#15 0x00007f4c07eacf25 in ?? ()
#16 0x00007f4c07eab85d in ?? ()
#17 0x00007f4c07e47926 in ?? ()
#18 0x00007f4c07e4a715 in MapWindow ()
#19 0x00007f4c07e4db34 in ReparentWindow ()
#20 0x00007f4c07e4dbd1 in HandleSaveSet ()
#21 0x00007f4c07e4216b in FreeClientResources ()
#22 0x00007f4c07e1e0df in CloseDownClient ()
#23 0x00007f4c07e1eb44 in ?? ()
#24 0x00007f4c07e22a9a in ?? ()
#25 0x00007f4c05905ec5 in __libc_start_main () from /lib/x86_64-linux-gnu/libc.so.6
#26 0x00007f4c07e0defe in _start ()

Thread 1 (Thread 0x7f4bfe0cf700 (LWP 1977)):
#0  0x00007f4c06ed2414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
#1  0x00007f4c00e634c3 in ?? () from /usr/lib/x86_64-linux-gnu/dri/r600_dri.so
#2  0x00007f4c00e62e07 in ?? () from /usr/lib/x86_64-linux-gnu/dri/r600_dri.so
#3  0x00007f4c06ece182 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
#4  0x00007f4c059df00d in clone () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) 
[Switching to thread 2 (Thread 0x7f4c07d879c0 (LWP 1793))]
#0  0x00007f4c059d5ec7 in ioctl () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) where
#0  0x00007f4c059d5ec7 in ioctl () from /lib/x86_64-linux-gnu/libc.so.6
#1  0x00007f4c06cbd3a4 in drmIoctl () from /usr/lib/x86_64-linux-gnu/libdrm.so.2
#2  0x00007f4c06cbf6bf in drmCommandWriteRead () from /usr/lib/x86_64-linux-gnu/libdrm.so.2
#3  0x00007f4c01820c83 in ?? () from /usr/lib/x86_64-linux-gnu/libdrm_radeon.so.1
#4  0x00007f4c01a77e88 in ?? () from /usr/lib/xorg/modules/drivers/radeon_drv.so
#5  0x00007f4c01a4a0f7 in ?? () from /usr/lib/xorg/modules/drivers/radeon_drv.so
#6  0x00007f4c013d1835 in ?? () from /usr/lib/xorg/modules/libexa.so
#7  0x00007f4c013d1a78 in ?? () from /usr/lib/xorg/modules/libexa.so
#8  0x00007f4c013d3323 in ?? () from /usr/lib/xorg/modules/libexa.so
#9  0x00007f4c013d3c9b in ?? () from /usr/lib/xorg/modules/libexa.so
#10 0x00007f4c07f52b7d in miCopyRegion ()
#11 0x00007f4c07f53106 in miDoCopy ()
#12 0x00007f4c013d2326 in ?? () from /usr/lib/xorg/modules/libexa.so
#13 0x00007f4c07eff838 in ?? ()
#14 0x00007f4c07eac0f8 in ?? ()
#15 0x00007f4c07eacf25 in ?? ()
#16 0x00007f4c07eab85d in ?? ()
#17 0x00007f4c07e47926 in ?? ()
#18 0x00007f4c07e4a715 in MapWindow ()
#19 0x00007f4c07e4db34 in ReparentWindow ()
#20 0x00007f4c07e4dbd1 in HandleSaveSet ()
#21 0x00007f4c07e4216b in FreeClientResources ()
#22 0x00007f4c07e1e0df in CloseDownClient ()
#23 0x00007f4c07e1eb44 in ?? ()
#24 0x00007f4c07e22a9a in ?? ()
#25 0x00007f4c05905ec5 in __libc_start_main () from /lib/x86_64-linux-gnu/libc.so.6
#26 0x00007f4c07e0defe in _start ()
(gdb) disass
Dump of assembler code for function ioctl:
   0x00007f4c059d5ec0 <+0>:     mov    $0x10,%eax
   0x00007f4c059d5ec5 <+5>:     syscall 
=> 0x00007f4c059d5ec7 <+7>:     cmp    $0xfffffffffffff001,%rax
   0x00007f4c059d5ecd <+13>:    jae    0x7f4c059d5ed0 <ioctl+16>
   0x00007f4c059d5ecf <+15>:    retq   
   0x00007f4c059d5ed0 <+16>:    mov    0x2ccf91(%rip),%rcx        # 0x7f4c05ca2e68
   0x00007f4c059d5ed7 <+23>:    neg    %eax
   0x00007f4c059d5ed9 <+25>:    mov    %eax,%fs:(%rcx)
   0x00007f4c059d5edc <+28>:    or     $0xffffffffffffffff,%rax
   0x00007f4c059d5ee0 <+32>:    retq   
End of assembler dump.
(gdb) info reg
rax            0xfffffffffffffe00       -512
rbx            0xffffffff       4294967295
rcx            0xffffffffffffffff       -1
rdx            0x7fff6377f4c0   140734862193856
rsi            0xc020645d       3223348317
rdi            0xc      12
rbp            0x7fff6377f4c0   0x7fff6377f4c0
rsp            0x7fff6377f468   0x7fff6377f468
r8             0x7f4c088756b0   139964537329328
r9             0x0      0
r10            0x7f4c0858c4f0   139964534277360
r11            0x246    582
r12            0xc020645d       3223348317
r13            0xc      12
r14            0x753000 7680000
r15            0x4      4
rip            0x7f4c059d5ec7   0x7f4c059d5ec7 <ioctl+7>
eflags         0x246    [ PF ZF IF ]
cs             0x33     51
ss             0x2b     43
ds             0x0      0
es             0x0      0
fs             0x0      0
gs             0x0      0
(gdb)

There were lots of errors from the 'gcore' command:



warning: Memory read failed for corefile section, 1048576 bytes at 0x7f4bf1dfd000.
warning: Memory read failed for corefile section, 1048576 bytes at 0x7f4bfb1a6000.
warning: Memory read failed for corefile section, 245760 bytes at 0x7f4bfb5bb000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfb795000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfb7fd000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfb805000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfb809000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfb811000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfb83b000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfb83f000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbdc1000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbdc5000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbdc9000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbdcd000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbdd1000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbdd5000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbdd9000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbddd000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbde1000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbde5000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbde9000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbef2000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbef6000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbefa000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbefe000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf02000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf06000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf0a000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf0e000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf12000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf16000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf1a000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf1e000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf22000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf26000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf2a000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf2e000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf32000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf36000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf3a000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf3e000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf42000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf46000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf4a000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf4e000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf52000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf56000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf5a000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf5e000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf62000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbf9f000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbfa3000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbfa7000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbfab000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbfaf000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbfb3000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbfb7000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbfbb000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbfbf000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbfc3000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbfc7000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbfd0000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbfd4000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbfd8000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbfdc000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbfe0000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbfe4000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbfe8000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbfec000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbff0000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbff4000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbff8000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfbffc000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc000000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc004000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc008000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc00c000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc010000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc014000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc018000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc01c000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc020000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc024000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc028000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc02c000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc030000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc034000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc038000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc03c000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc040000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc044000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc048000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc04c000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc050000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc054000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc058000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc05c000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc060000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc064000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc068000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc06c000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc070000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc074000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc078000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc07c000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc080000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc084000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc088000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc08c000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc090000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc094000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc098000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc09c000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc0a0000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc0a4000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc0a8000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc0ac000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc0b0000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc0b4000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc0b8000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc0cd000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc0d1000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc0d5000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc0d9000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc0dd000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc0e1000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc0e5000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc0e9000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc0ed000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc0f1000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc0f5000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc0f9000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc0fd000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc101000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc105000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc109000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc10d000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc111000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc115000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc119000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc11d000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc121000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc125000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc129000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc12d000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc131000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc135000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc139000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc13d000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc141000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc15a000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc15e000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc162000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc166000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc16a000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc16e000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc172000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc176000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc18c000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc190000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc194000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc198000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc227000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4bfc22b000.
warning: Memory read failed for corefile section, 1048576 bytes at 0x7f4bfc643000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07bc7000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07bcb000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07be0000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07be4000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07be8000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07bec000.
warning: Memory read failed for corefile section, 8192 bytes at 0x7f4c07bf0000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07bf3000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07bf7000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07bfb000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07bff000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07c03000.
warning: Memory read failed for corefile section, 4096 bytes at 0x7f4c07c1f000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07c21000.
warning: Memory read failed for corefile section, 4096 bytes at 0x7f4c07c69000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07c6a000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07c71000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07c75000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07c79000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07c7d000.
warning: Memory read failed for corefile section, 65536 bytes at 0x7f4c07c81000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07c91000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07c95000.
warning: Memory read failed for corefile section, 8192 bytes at 0x7f4c07c9c000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07ca1000.
warning: Memory read failed for corefile section, 8192 bytes at 0x7f4c07ca5000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07ca7000.
warning: Memory read failed for corefile section, 4096 bytes at 0x7f4c07d95000.
warning: Memory read failed for corefile section, 4096 bytes at 0x7f4c07d96000.
warning: Memory read failed for corefile section, 4096 bytes at 0x7f4c07d97000.
warning: Memory read failed for corefile section, 4096 bytes at 0x7f4c07d98000.
warning: Memory read failed for corefile section, 4096 bytes at 0x7f4c07d9a000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07d9b000.
warning: Memory read failed for corefile section, 4096 bytes at 0x7f4c07d9f000.
warning: Memory read failed for corefile section, 4096 bytes at 0x7f4c07da0000.
warning: Memory read failed for corefile section, 65536 bytes at 0x7f4c07da1000.
warning: Memory read failed for corefile section, 8192 bytes at 0x7f4c07db1000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07db3000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07db7000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07dbb000.
warning: Memory read failed for corefile section, 16384 bytes at 0x7f4c07dbf000.

Good luck debugging this one ! Let me know if I can be of any further help.
Thanks & Regards, Jason