[alsa-devel] pcm_lib.c: XRUN alsa-back-porting

A customer is reporting that he's seeing this message every now and then, but when I try to examine the kernel source code, I don't see the source of it. In fact, when I do a google search of "alsa-back-porting", I get zero hits. So maybe the customer is using some older kernel, but when I scan the git change history for sound/core/pcm_lib.c, I still don't see it.

So can someone tell me what "alsa-back-porting" means, and where it comes from?