Full backtrace:
#0  sse2_blt (src_bits=<optimized out>, dst_bits=<optimized out>, src_stride=<optimized out>, dst_stride=<optimized out>, src_bpp=<optimized out>, src_x=<optimized out>, src_y=0, dest_x=0, dest_y=0, width=1024, height=<optimized out>, dst_bpp=<optimized out>, imp=<optimized out>) at ../../pixman/pixman-sse2.c:4773
        w = 4160
        s = 0x7f702985e530 "\300\300\300"
        d = 0x7f70226d3fd0 "\300\300\300"
        src_bytes = 0x7f702985d130 "\277\277\277\261\277\277\277\260\277\277\277\257\277\277\277\256\277\277\277\257\277\277\277\261\300\300\300\261\300\300\300\260\277\277\277\261\277\277\277\261\277\277\277\260\277\277\277\257\277\277\277\262\277\277\277\261\277\277\277\262\300\300\300\261\300\300\300\261\300\300\300\261\277\277\277\257\277\277\277\261\277\277\277\261\277\277\277\261\277\277\277\260\300\300\300\262\277\277\277\261\277\277\277\260\277\277\277\260\277\277\277\260\277\277\277\261\277\277\277\261\277\277\277\261\277\277\277\261\277\277\277\261\277\277\277\260\277\277\277\261\277\277\277\261\277\277\277\261\277\277\277\260\277\277\277\261\277\277\277\261\277\277\277\261\277\277\277\260\277\277\277\262\277\277\277\261\277\277\277\261\277\277\277\260\277\277\277\261\277\277\277\261\277\277\277\261\277\277\277\261"...
        dst_bytes = <optimized out>
        byte_width = 4096
#1  0x00007f70360efa39 in sse2_blt (height=768, width=1024, dest_y=0, dest_x=<optimized out>, src_y=<optimized out>, src_x=<optimized out>, dst_bpp=<optimized out>, src_bpp=<optimized out>, dst_stride=<optimized out>, src_stride=<optimized out>, dst_bits=<optimized out>, src_bits=<optimized out>, imp=<optimized out>) at ../../pixman/pixman-sse2.c:4822
No locals.
#2  sse2_composite_copy_area (imp=<optimized out>, info=<optimized out>) at ../../pixman/pixman-sse2.c:4815
        op = <optimized out>
        src_image = <optimized out>
        mask_image = <optimized out>
        dest_image = <optimized out>
        src_x = <optimized out>
        src_y = <optimized out>
        mask_x = <optimized out>
        mask_y = <optimized out>
        dest_x = <optimized out>
        dest_y = 0
        width = 1024
        height = 768
#3  0x00007f7036067711 in pixman_image_composite32 (op=op@entry=PIXMAN_OP_SRC, src=<optimized out>, mask=mask@entry=0x0, dest=<optimized out>, src_x=src_x@entry=0, src_y=src_y@entry=0, mask_x=0, mask_y=0, dest_x=0, dest_y=0, width=1024, height=768) at ../../pixman/pixman.c:707
        src_format = <optimized out>
        mask_format = 0
        dest_format = PIXMAN_a8r8g8b8
        region = {extents = {x1 = 0, y1 = 0, x2 = 1024, y2 = 768}, data = 0x0}
        extents = {x1 = 0, y1 = 0, x2 = 1024, y2 = 768}
        imp = 0x7f7038e848a0
        func = 0x7f70360ef9d0 <sse2_composite_copy_area>
        info = {op = PIXMAN_OP_SRC, src_image = 0x7f7039267e90, mask_image = 0x0, dest_image = 0x7f70392603d0, src_x = 0, src_y = 0, mask_x = 0, mask_y = 0, dest_x = 0, dest_y = 0, width = 1024, height = 768, src_flags = 42420863, mask_flags = 8194, dest_flags = 34032255}
        pbox = 0x7fff9ba9e060
        n = 0
#4  0x00007f70360677e3 in pixman_image_composite (op=op@entry=PIXMAN_OP_SRC, src=<optimized out>, mask=mask@entry=0x0, dest=<optimized out>, src_x=src_x@entry=0, src_y=src_y@entry=0, mask_x=<optimized out>, mask_y=<optimized out>, dest_x=<optimized out>, dest_y=<optimized out>, width=<optimized out>, height=<optimized out>) at ../../pixman/pixman.c:730
No locals.
#5  0x00007f7030e61ca8 in download_box_no_update (surface=0x7f7037402f88, surface=0x7f7037402f88, y2=<optimized out>, x2=<optimized out>, y1=0, x1=0) at ../../src/qxl_surface.c:133
No locals.
#6  qxl_download_box (surface=0x7f7037402f88, x1=0, y1=0, x2=<optimized out>, y2=<optimized out>) at ../../src/qxl_surface.c:150
No locals.
#7  0x00007f7030e61daf in qxl_surface_prepare_access (surface=0x7f7037402f88, pixmap=0x7f70392c3fa0, region=0x7fff9ba9e190, access=<optimized out>) at ../../src/qxl_surface.c:183
        n_boxes = <optimized out>
        boxes = 0x7fff9ba9e190
        pScreen = 0x7f7038ea9e50
        pScrn = <optimized out>
        new = {extents = {x1 = 0, y1 = 0, x2 = 1024, y2 = 768}, data = 0x0}
#8  0x00007f7030e6cd6d in uxa_prepare_access (pDrawable=0x7f70392c3fa0, region=0x7fff9ba9e200, region@entry=0x0, access=access@entry=UXA_ACCESS_RO) at ../../../src/uxa/uxa.c:172
        pScreen = <optimized out>
        xoff = 0
        yoff = 0
        pPixmap = 0x7f70392c3fa0
        box = {x1 = 0, y1 = 0, x2 = <optimized out>, y2 = <optimized out>}
        region_rec = {extents = {x1 = 0, y1 = 0, x2 = 1024, y2 = 768}, data = 0x0}
        result = 1
#9  0x00007f7030e6d0f0 in uxa_prepare_access_window (pWin=0x7f7038f2ef70) at ../../../src/uxa/uxa.c:310
No locals.
#10 0x00007f7030e6d187 in uxa_change_window_attributes (pWin=0x7f7038f2ef70, mask=1) at ../../../src/uxa/uxa.c:343
        ret = <optimized out>
        need_access = 1
#11 0x00007f70371346fd in ?? ()
No symbol table info available.
#12 0x00007f70370d5ef4 in ChangeWindowAttributes ()
No symbol table info available.
#13 0x00007f70370a22f6 in ?? ()
No symbol table info available.
#14 0x00007f70370a8117 in ?? ()
No symbol table info available.
#15 0x00007f70370ac29b in ?? ()
No symbol table info available.
#16 0x00007f7034f70b45 in __libc_start_main (main=0x7f7037096660, argc=7, argv=0x7fff9ba9e588, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fff9ba9e578) at libc-start.c:287
        result = <optimized out>
        unwind_buf = {cancel_jmp_buf = {{jmp_buf = {0, 1261194766413414073, 140119936427621, 140735804990848, 0, 0, -1261114930715214151, -1197746277989925191}, mask_was_saved = 0}}, priv = {pad = {0x0, 0x0, 0x7f7037213d90 <__libc_csu_init>, 0x7fff9ba9e588}, data = {prev = 0x0, cleanup = 0x0, canceltype = 924925328}}}
        not_first_call = <optimized out>
#17 0x00007f703709668e in _start ()
No symbol table info available.


Registers:
rax            0x7f70221d3010	140119585402896
rbx            0x7f702985d130	140119709700400
rcx            0x7f702985e530	140119709705520
rdx            0x1000	4096
rsi            0x7f70226d4010	140119590649872
rdi            0x7f702985e530	140119709705520
rbp            0x1400	0x1400
rsp            0x7fff9ba9df88	0x7fff9ba9df88
r8             0x1000	4096
r9             0x7f70221d3010	140119585402896
r10            0x300	768
r11            0x1000	4096
r12            0xffffffffffffec00	-5120
r13            0x0	0
r14            0x0	0
r15            0x0	0
rip            0x7f70360ef8eb	0x7f70360ef8eb <sse2_blt+459>
eflags         0x13202	[ IF #12 #13 RF ]
cs             0x33	51
ss             0x2b	43
ds             0x0	0
es             0x0	0
fs             0x0	0
gs             0x0	0


Current instructions:
=> 0x7f70360ef8eb <sse2_blt+459>:	movaps %xmm0,-0x10(%rsi)
   0x7f70360ef8ef <sse2_blt+463>:	cmp    $0x3f,%r8d
   0x7f70360ef8f3 <sse2_blt+467>:	jg     0x7f70360ef8c0 <sse2_blt+416>
   0x7f70360ef8f5 <sse2_blt+469>:	sub    $0x40,%edx
   0x7f70360ef8f8 <sse2_blt+472>:	mov    %edx,%esi
   0x7f70360ef8fa <sse2_blt+474>:	shr    $0x6,%esi
   0x7f70360ef8fd <sse2_blt+477>:	mov    %esi,%ecx
   0x7f70360ef8ff <sse2_blt+479>:	shl    $0x6,%esi
   0x7f70360ef902 <sse2_blt+482>:	add    $0x1,%rcx
   0x7f70360ef906 <sse2_blt+486>:	sub    %esi,%edx
   0x7f70360ef908 <sse2_blt+488>:	shl    $0x6,%rcx
   0x7f70360ef90c <sse2_blt+492>:	add    %rcx,%rdi
   0x7f70360ef90f <sse2_blt+495>:	add    %rcx,%rax
   0x7f70360ef912 <sse2_blt+498>:	jmpq   0x7f70360ef7cf <sse2_blt+175>
   0x7f70360ef917 <sse2_blt+503>:	lea    (%rdx,%rdx,1),%eax
   0x7f70360ef91a <sse2_blt+506>:	movslq %r9d,%r9


Threads backtrace:

Thread 3 (Thread 0x7f7023f72700 (LWP 2260)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007f7027bfa463 in ?? () from /usr/lib/x86_64-linux-gnu/dri/swrast_dri.so
#2  0x00007f7027bf9cc7 in ?? () from /usr/lib/x86_64-linux-gnu/dri/swrast_dri.so
#3  0x00007f70347160a4 in start_thread (arg=0x7f7023f72700) at pthread_create.c:309
#4  0x00007f703503507d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111

Thread 2 (Thread 0x7f7024773700 (LWP 2259)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007f7027bfa463 in ?? () from /usr/lib/x86_64-linux-gnu/dri/swrast_dri.so
#2  0x00007f7027bf9cc7 in ?? () from /usr/lib/x86_64-linux-gnu/dri/swrast_dri.so
#3  0x00007f70347160a4 in start_thread (arg=0x7f7024773700) at pthread_create.c:309
#4  0x00007f703503507d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111

Thread 1 (Thread 0x7f7037451980 (LWP 2255)):
#0  sse2_blt (src_bits=<optimized out>, dst_bits=<optimized out>, src_stride=<optimized out>, dst_stride=<optimized out>, src_bpp=<optimized out>, src_x=<optimized out>, src_y=0, dest_x=0, dest_y=0, width=1024, height=<optimized out>, dst_bpp=<optimized out>, imp=<optimized out>) at ../../pixman/pixman-sse2.c:4773
#1  0x00007f70360efa39 in sse2_blt (height=768, width=1024, dest_y=0, dest_x=<optimized out>, src_y=<optimized out>, src_x=<optimized out>, dst_bpp=<optimized out>, src_bpp=<optimized out>, dst_stride=<optimized out>, src_stride=<optimized out>, dst_bits=<optimized out>, src_bits=<optimized out>, imp=<optimized out>) at ../../pixman/pixman-sse2.c:4822
#2  sse2_composite_copy_area (imp=<optimized out>, info=<optimized out>) at ../../pixman/pixman-sse2.c:4815
#3  0x00007f7036067711 in pixman_image_composite32 (op=op@entry=PIXMAN_OP_SRC, src=<optimized out>, mask=mask@entry=0x0, dest=<optimized out>, src_x=src_x@entry=0, src_y=src_y@entry=0, mask_x=0, mask_y=0, dest_x=0, dest_y=0, width=1024, height=768) at ../../pixman/pixman.c:707
#4  0x00007f70360677e3 in pixman_image_composite (op=op@entry=PIXMAN_OP_SRC, src=<optimized out>, mask=mask@entry=0x0, dest=<optimized out>, src_x=src_x@entry=0, src_y=src_y@entry=0, mask_x=<optimized out>, mask_y=<optimized out>, dest_x=<optimized out>, dest_y=<optimized out>, width=<optimized out>, height=<optimized out>) at ../../pixman/pixman.c:730
#5  0x00007f7030e61ca8 in download_box_no_update (surface=0x7f7037402f88, surface=0x7f7037402f88, y2=<optimized out>, x2=<optimized out>, y1=0, x1=0) at ../../src/qxl_surface.c:133
#6  qxl_download_box (surface=0x7f7037402f88, x1=0, y1=0, x2=<optimized out>, y2=<optimized out>) at ../../src/qxl_surface.c:150
#7  0x00007f7030e61daf in qxl_surface_prepare_access (surface=0x7f7037402f88, pixmap=0x7f70392c3fa0, region=0x7fff9ba9e190, access=<optimized out>) at ../../src/qxl_surface.c:183
#8  0x00007f7030e6cd6d in uxa_prepare_access (pDrawable=0x7f70392c3fa0, region=0x7fff9ba9e200, region@entry=0x0, access=access@entry=UXA_ACCESS_RO) at ../../../src/uxa/uxa.c:172
#9  0x00007f7030e6d0f0 in uxa_prepare_access_window (pWin=0x7f7038f2ef70) at ../../../src/uxa/uxa.c:310
#10 0x00007f7030e6d187 in uxa_change_window_attributes (pWin=0x7f7038f2ef70, mask=1) at ../../../src/uxa/uxa.c:343
#11 0x00007f70371346fd in ?? ()
#12 0x00007f70370d5ef4 in ChangeWindowAttributes ()
#13 0x00007f70370a22f6 in ?? ()
#14 0x00007f70370a8117 in ?? ()
#15 0x00007f70370ac29b in ?? ()
#16 0x00007f7034f70b45 in __libc_start_main (main=0x7f7037096660, argc=7, argv=0x7fff9ba9e588, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fff9ba9e578) at libc-start.c:287
#17 0x00007f703709668e in _start ()