On Mon, 26 Nov 2018 01:28:05 +0100, kernel test robot wrote:

FYI, we noticed the following commit (built with gcc-7):

commit: 3a6d1980fe96dbbfe3ae58db0048867f5319cdbf ("ALSA: Replace snd_malloc_pages() and snd_free_pages() with standard helpers") https://git.kernel.org/cgit/linux/kernel/git/tiwai/sound.git for-next

....

[ 174.830284] kernel BUG at mm/page_alloc.c:2850!

OK, this seem to be an issue about using __GFP_COMP and alloc_pages_exact(). I didn't hit this while testing locally maybe just because I used the buffer size in power-of-two casually.

I dropped the patch until we sort this out.

thanks,

Takashi