mm/cma: provide option to opt out from exposing pages on activation failure

mm/cma: provide option to opt out from exposing pages on activation failure

Patch series "powerpc/fadump: handle CMA activation failure appropriately", v3.

Commit 072355c1cf2d ("mm/cma: expose all pages to the buddy if activation
of an area fails") started exposing all pages to buddy allocator on CMA
activation failure.  But there can be CMA users that want to handle the
reserved memory differently on CMA allocation failure.  Provide an option
to opt out from exposing pages to buddy for such cases.

Link: https://lkml.kernel.org/r/20220117075246.36072-1-hbathini@linux.ibm.com
Link: https://lkml.kernel.org/r/20220117075246.36072-2-hbathini@linux.ibm.com
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Cc: Sourabh Jain <sourabhjain@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>