mm: cma: allocation trigger

Provides a userspace interface to trigger a CMA allocation.

Usage:

        echo [pages] > alloc

This would provide testing/fuzzing access to the CMA allocation paths.

Change-Id: I2c1539ac29267f146d697b1f059e648a6b21c656
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Git-commit: 26b02a1f9670862c51b3ff63a6128589866f5c71
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Liam Mark <lmark@codeaurora.org>