Error 4 means "The cause was a user-mode read resulting in no page being found.". There's a tool that decodes it here.
Here's the definition from the kernel. Keep in mind that 4 means that bit 2 is set and no other bits are set. If you convert it to binary that becomes clear.
/*
* Page fault error code bits
* bit 0 == 0 means no page found, 1 means protection fault
* bit 1 == 0 means read, 1 means write
* bit 2 == 0 means kernel, 1 means user-mode
* bit 3 == 1 means use of reserved bit detected
* bit 4 == 1 means fault was an instruction fetch
*/
#define PF_PROT (1<<0)
#define PF_WRITE (1<<1)
#define PF_USER (1<<2)
#define PF_RSVD (1<<3)
#define PF_INSTR (1<<4)
Now then, "ip 00007f9bebcca90d" means the instruction pointer was at 0x00007f9bebcca90d when the segfault happened.
"libQtWebKit.so.4.5.2[7f9beb83a000+f6f000]" tells you:
If you take the base address and subtract it from the ip, you get the offset into that object:
0x00007f9bebcca90d - 0x7f9beb83a000 = 0x49090D
Then you can run addr2line on it:
addr2line -e /usr/lib64/qt45/lib/libQtWebKit.so.4.5.2 -fCi 0x49090D
??
??:0
In my case it wasn't successful, either the copy I installed isn't identical to yours, or it's stripped.