(gdb) bt
#0  0xf29b14fa in mix_areas_32_smp (size=3935624896, dst=0x56a6e7f0, src=0x56a6e7f0, sum=0x1, dst_step=4, src_step=4, sum_step=4)
    at /tmp/portage/media-libs/alsa-lib-1.1.6-r1/work/alsa-lib-1.1.6/src/pcm/pcm_dmix_x86_64.h:143
#1  0xf29b2361 in mix_areas (size=3935493824, dst_ofs=4056, src_ofs=0, dst_areas=0x56a6cd90, src_areas=0x56a6dc30, dmix=0x56a6c900)
    at /tmp/portage/media-libs/alsa-lib-1.1.6-r1/work/alsa-lib-1.1.6/src/pcm/pcm_dmix.c:197
#2  snd_pcm_dmix_sync_area (pcm=pcm@entry=0x56a6d270)
    at /tmp/portage/media-libs/alsa-lib-1.1.6-r1/work/alsa-lib-1.1.6/src/pcm/pcm_dmix.c:379
#3  0xf29b267f in snd_pcm_dmix_start (pcm=<optimized out>)
    at /tmp/portage/media-libs/alsa-lib-1.1.6-r1/work/alsa-lib-1.1.6/src/pcm/pcm_dmix.c:611
#4  0xf2972349 in __snd_pcm_start (pcm=0x56a6d270, pcm=0x56a6d270)
    at /tmp/portage/media-libs/alsa-lib-1.1.6-r1/work/alsa-lib-1.1.6/src/pcm/pcm_local.h:434
#5  snd_pcm_start (pcm=<optimized out>) at /tmp/portage/media-libs/alsa-lib-1.1.6-r1/work/alsa-lib-1.1.6/src/pcm/pcm.c:1226
#6  0xf2972349 in __snd_pcm_start (pcm=0x56a6d8b0, pcm=0x56a6d8b0)
    at /tmp/portage/media-libs/alsa-lib-1.1.6-r1/work/alsa-lib-1.1.6/src/pcm/pcm_local.h:434
#7  snd_pcm_start (pcm=<optimized out>) at /tmp/portage/media-libs/alsa-lib-1.1.6-r1/work/alsa-lib-1.1.6/src/pcm/pcm.c:1226
#8  0xf2979a78 in __snd_pcm_start (pcm=0x56a52e60, pcm=0x56a52e60)
    at /tmp/portage/media-libs/alsa-lib-1.1.6-r1/work/alsa-lib-1.1.6/src/pcm/pcm_local.h:434
#9  snd1_pcm_write_areas (pcm=pcm@entry=0x56a52e60, areas=areas@entry=0xe47f2f00, offset=offset@entry=0, size=<optimized out>, 
    size@entry=12288, func=func@entry=0xf2988770 <snd_pcm_plugin_write_areas>)
    at /tmp/portage/media-libs/alsa-lib-1.1.6-r1/work/alsa-lib-1.1.6/src/pcm/pcm.c:7421
#10 0xf29890e7 in snd_pcm_plugin_writei (pcm=<optimized out>, buffer=<optimized out>, size=12288)
    at /tmp/portage/media-libs/alsa-lib-1.1.6-r1/work/alsa-lib-1.1.6/src/pcm/pcm_plugin.c:358
#11 0x56590280 in ?? ()
#12 0x56594846 in ?? ()
#13 0xf1b9808b in start_thread () from /libx32/libpthread.so.0
#14 0xf18d4e2f in clone () from /libx32/libc.so.6
(gdb)