mm/cma: drop incorrect alignment check in cma_init_reserved_mem

cma_init_reserved_mem uses IS_ALIGNED to check if the size represented by
one bit in the cma allocation bitmask is aligned with
CMA_MIN_ALIGNMENT_BYTES (pageblock size).

However, this is too strict, as this will fail if order_per_bit >
pageblock_order, which is a valid configuration.

We could check IS_ALIGNED both ways, but since both numbers are powers of
two, no check is needed at all.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: de9e14e ("drivers: dma-contiguous: add initialization from device tree")
Signed-off-by: Frank van der Linden <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Cc: Marek Szyprowski <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

mm/cma.c

@@ -182,10 +182,6 @@ int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
 	if (!size || !memblock_is_region_reserved(base, size))
 		return -EINVAL;
 
-	/* alignment should be aligned with order_per_bit */
-	if (!IS_ALIGNED(CMA_MIN_ALIGNMENT_PAGES, 1 << order_per_bit))
-		return -EINVAL;
-
 	/* ensure minimal alignment required by mm core */
 	if (!IS_ALIGNED(base | size, CMA_MIN_ALIGNMENT_BYTES))
 		return -EINVAL;