On my system ALSA sometimes hangs:
sysrq: SysRq : Show Blocked State task PC stack pid father output:ALSA def D 0 171 1 0x00000000 Call Trace: ? __schedule+0x17c/0x720 ? schedule_preempt_disabled+0x2d/0x80 ? __mutex_lock_slowpath+0x141/0x420 ? snd_pcm_common_ioctl1+0x2f/0x1400 ? snd_pcm_common_ioctl1+0x2f/0x1400 ? snd_card_file_remove+0x76/0x120 ? snd_pcm_playback_ioctl+0x1c7/0x560 ? dput+0xb6/0x1e0 ? SyS_ioctl+0xa7/0x860 ? task_work_run+0x70/0xa0 ? entry_SYSCALL_64_fastpath+0x13/0x94
Only a reboot will fix the issue.