[PATCH v5 4/6] mm: cma: use pageblock_order as the single alignment

[Zi Yan]

From: Zi Yan <ziy at nvidia.com>

Now alloc_contig_range() works at pageblock granularity. Change CMA
allocation, which uses alloc_contig_range(), to use pageblock_order
alignment.

Signed-off-by: Zi Yan <ziy at nvidia.com>
---
 include/linux/mmzone.h  | 5 +----
 kernel/dma/contiguous.c | 2 +-
 mm/cma.c                | 6 ++----
 mm/page_alloc.c         | 4 ++--
 4 files changed, 6 insertions(+), 11 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 3fff6deca2c0..da38c8436493 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -54,10 +54,7 @@ enum migratetype {
 	 *
 	 * The way to use it is to change migratetype of a range of
 	 * pageblocks to MIGRATE_CMA which can be done by
-	 * __free_pageblock_cma() function.  What is important though
-	 * is that a range of pageblocks must be aligned to
-	 * MAX_ORDER_NR_PAGES should biggest page be bigger than
-	 * a single pageblock.
+	 * __free_pageblock_cma() function.
 	 */
 	MIGRATE_CMA,
 #endif
diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
index 3d63d91cba5c..ac35b14b0786 100644
--- a/kernel/dma/contiguous.c
+++ b/kernel/dma/contiguous.c
@@ -399,7 +399,7 @@ static const struct reserved_mem_ops rmem_cma_ops = {
 
 static int __init rmem_cma_setup(struct reserved_mem *rmem)
 {
-	phys_addr_t align = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
+	phys_addr_t align = PAGE_SIZE << pageblock_order;
 	phys_addr_t mask = align - 1;
 	unsigned long node = rmem->fdt_node;
 	bool default_cma = of_get_flat_dt_prop(node, "linux,cma-default", NULL);
diff --git a/mm/cma.c b/mm/cma.c
index 766f1b82b532..b2e927fab7b5 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -187,8 +187,7 @@ int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
 		return -EINVAL;
 
 	/* ensure minimal alignment required by mm core */
-	alignment = PAGE_SIZE <<
-			max_t(unsigned long, MAX_ORDER - 1, pageblock_order);
+	alignment = PAGE_SIZE << pageblock_order;
 
 	/* alignment should be aligned with order_per_bit */
 	if (!IS_ALIGNED(alignment >> PAGE_SHIFT, 1 << order_per_bit))
@@ -275,8 +274,7 @@ int __init cma_declare_contiguous_nid(phys_addr_t base,
 	 * migratetype page by page allocator's buddy algorithm. In the case,
 	 * you couldn't get a contiguous memory, which is not what we want.
 	 */
-	alignment = max(alignment,  (phys_addr_t)PAGE_SIZE <<
-			  max_t(unsigned long, MAX_ORDER - 1, pageblock_order));
+	alignment = max(alignment,  (phys_addr_t)PAGE_SIZE << pageblock_order);
 	if (fixed && base & (alignment - 1)) {
 		ret = -EINVAL;
 		pr_err("Region at %pa must be aligned to %pa bytes\n",
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 7a4fa21aea5c..ac9432e63ce1 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -9214,8 +9214,8 @@ int isolate_single_pageblock(unsigned long boundary_pfn, gfp_t gfp_flags,
  *			be either of the two.
  * @gfp_mask:	GFP mask to use during compaction
  *
- * The PFN range does not have to be pageblock or MAX_ORDER_NR_PAGES
- * aligned.  The PFN range must belong to a single zone.
+ * The PFN range does not have to be pageblock aligned. The PFN range must
+ * belong to a single zone.
  *
  * The first thing this routine does is attempt to MIGRATE_ISOLATE all
  * pageblocks in the range.  Once isolated, the pageblocks should not
-- 
2.34.1