Comment 23 for bug 1823753

Note: We have tested https://lkml.org/lkml/2019/5/6/1221, which is now on linux-next *, and the hi162 RoCE driver single patch usage is diminished:
$cat cma.disco.dmesg | grep "cma: cma_alloc(cma" | sed -r 's/.*count ([0-9]+)\,.*/\1/' | sort -n | uniq -c
129 2
3 4
206 8
32 16
2 24
4 32
256 33
39 64
2 128
2 1024

I think that we had ~11K x 1K CMA pages previously, without this patchset.

* https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/log/kernel/dma?h=next-20190530