Since CMA is used more widely, it's worth to have CMA allocation
statistics into vmstat.  With it, we could know how agressively system
uses cma allocation and how often it fails.

Link: https://lkml.kernel.org/r/20210302183346.3707237-1-minchan@kernel.orgSigned-off-by: NMinchan Kim <minchan@kernel.org>
Reviewed-by: NJohn Hubbard <jhubbard@nvidia.com>
Cc: John Dias <joaodias@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>