Comment 7 for bug 1823753

I only had time to look briefly, but here's a few notes. Firstly, a workaround for now is passing cma=0 on the kernel command line.

I feel like there must be something wrong here if everything just works fine with CMA turned off, because obviously devices are getting CMA allocations when they don't really need them. I'm not familiar with CMA, but my assumption would be that you want as small a region as possible for it and thus you want to only use it for devices where it's actually necessary. Shooting from the hip I'd guess that one of two things is wrong, either some devices are doing their allocations wrong and getting CMA memory when they don't need it, or the DMA allocator is over zealous in its use of CMA.