+ mm-cma-drop-incorrect-alignment-check-in-cma_init_reserved_mem.patch added to mm-unstable branch

+ mm-cma-drop-incorrect-alignment-check-in-cma_init_reserved_mem.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/cma: drop incorrect alignment check in cma_init_reserved_mem
has been added to the -mm mm-unstable branch.  Its filename is
     mm-cma-drop-incorrect-alignment-check-in-cma_init_reserved_mem.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-cma-drop-incorrect-alignment-check-in-cma_init_reserved_mem.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Frank van der Linden <fvdl@google.com>
Subject: mm/cma: drop incorrect alignment check in cma_init_reserved_mem
Date: Thu, 4 Apr 2024 16:25:14 +0000

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>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/cma.c |    4 ----
 1 file changed, 4 deletions(-)

--- a/mm/cma.c~mm-cma-drop-incorrect-alignment-check-in-cma_init_reserved_mem
+++ a/mm/cma.c
@@ -182,10 +182,6 @@ int __init cma_init_reserved_mem(phys_ad
 	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;
_

Patches currently in -mm which might be from fvdl@google.com are

mm-cma-drop-incorrect-alignment-check-in-cma_init_reserved_mem.patch
mm-hugetlb-pass-correct-order_per_bit-to-cma_declare_contiguous_nid.patch