(gdb) bt
#0  0x00007fa4fcb27cd7 in ioctl () from /lib/libc.so.6
#1  0x00007fa4fb1452cd in drmDMA () from /usr/lib/libdrm.so.2
#2  0x00007fa4facb293d in RADEONCPGetBuffer (pScrn=0x1eea300) at ../../src/radeon_accel.c:651
#3  0x00007fa4fad03d64 in RADEONPrepareSolidCP (pPix=0x29abdb0, alu=3, pm=4294967295, fg=0)
    at ../../src/radeon_exa_funcs.c:92
#4  0x00007fa4fa444786 in exaFillRegionSolid (pDrawable=0x29abdb0, pRegion=0x3079f70, pixel=0, planemask=4294967295, alu=3)
    at ../../exa/exa_accel.c:939
#5  0x00007fa4fa4461ca in exaPolyFillRect (pDrawable=0x29abdb0, pGC=0x299c070, nrect=1, prect=0x2982f2c)
    at ../../exa/exa_accel.c:751
#6  0x000000000053a866 in damagePolyFillRect (pDrawable=0x29abdb0, pGC=0x299c070, nRects=1, pRects=0x2982f2c)
    at ../../../miext/damage/damage.c:1404
#7  0x000000000044b5b6 in ProcPolyFillRectangle (client=0x297efd0) at ../../dix/dispatch.c:1769
#8  0x000000000044e304 in Dispatch () at ../../dix/dispatch.c:437
#9  0x0000000000433d8d in main (argc=10, argv=0x7fff06f4cd88, envp=<value optimized out>) at ../../dix/main.c:397
(gdb) info registers
rax            0xfffffffffffffff0	-16
rbx            0x0	0
rcx            0xffffffffffffffff	-1
rdx            0x7fff06f4c8c0	140733310093504
rsi            0xc0406429	3225445417
rdi            0xa	10
rbp            0x7fff06f4c940	0x7fff06f4c940
rsp            0x7fff06f4c8b8	0x7fff06f4c8b8
r8             0x1	1
r9             0x1	1
r10            0x0	0
r11            0x3246	12870
r12            0x1eea300	32416512
r13            0xa	10
r14            0x1ef9e00	32480768
r15            0xa95	2709
rip            0x7fa4fcb27cd7	0x7fa4fcb27cd7 <ioctl+7>
eflags         0x3246	[ PF ZF IF #12 #13 ]
cs             0x33	51
ss             0x2b	43
ds             0x0	0
es             0x0	0
fs             0x0	0
gs             0x0	0
fctrl          0x37f	895
fstat          0x0	0
ftag           0xffff	65535
fiseg          0x0	0
fioff          0x0	0
foseg          0x0	0
fooff          0x0	0
fop            0x0	0
mxcsr          0x1f80	[ IM DM ZM OM UM PM ]
(gdb) disassemble
Dump of assembler code for function ioctl:
0x00007fa4fcb27cd0 <ioctl+0>:	mov    $0x10,%eax
0x00007fa4fcb27cd5 <ioctl+5>:	syscall 
0x00007fa4fcb27cd7 <ioctl+7>:	cmp    $0xfffffffffffff001,%rax
0x00007fa4fcb27cdd <ioctl+13>:	jae    0x7fa4fcb27ce0 <ioctl+16>
0x00007fa4fcb27cdf <ioctl+15>:	retq   
0x00007fa4fcb27ce0 <ioctl+16>:	mov    0x28e2a9(%rip),%rcx        # 0x7fa4fcdb5f90
0x00007fa4fcb27ce7 <ioctl+23>:	xor    %edx,%edx
0x00007fa4fcb27ce9 <ioctl+25>:	sub    %rax,%rdx
0x00007fa4fcb27cec <ioctl+28>:	mov    %edx,%fs:(%rcx)
0x00007fa4fcb27cef <ioctl+31>:	or     $0xffffffffffffffff,%rax
0x00007fa4fcb27cf3 <ioctl+35>:	jmp    0x7fa4fcb27cdf <ioctl+15>
End of assembler dump.