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/20240404162515.527802-1-fvdl@google.com
Fixes: de9e14eebf33 ("drivers: dma-contiguous: add initialization from device tree")
Signed-off-by: Frank van der Linden <fvdl@google.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/cma.c b/mm/cma.c
index 01f5a8f71ddfa7dc98ca3919f45ce61682d9bf11..3e9724716bad87a2d1f1a7d2184864845f3e289d 100644 (file)
--- a/mm/cma.c
+++ b/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;