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

Zi Yan
2022-02-11T16:51:17Z

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@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