From: Zi Yan <ziy@nvidia.com>

It keeps the existing behavior when MAX_ORDER grows beyond a section
size.

Signed-off-by: Zi Yan <ziy@nvidia.com>
Cc: David Hildenbrand <redacted>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: virtualization@lists.linux-foundation.org
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
---
  drivers/virtio/virtio_mem.c | 12 ++++++------
  1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index 19036922f7ef..bab5a81fa796 100644
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c

@@ -1105,11 +1105,11 @@ static void virtio_mem_clear_fake_offline(unsigned long pfn,
   */
  static void virtio_mem_fake_online(unsigned long pfn, unsigned long nr_pages)
  {
-	const unsigned long max_nr_pages = MAX_ORDER_NR_PAGES;
+	const unsigned long max_nr_pages = PAGES_PER_SECTION;
  	unsigned long i;
  
  	/*
-	 * We are always called at least with MAX_ORDER_NR_PAGES
+	 * We are always called at least with PAGES_PER_SECTION
  	 * granularity/alignment (e.g., the way subblocks work). All pages
  	 * inside such a block are alike.
  	 */

@@ -1125,7 +1125,7 @@ static void virtio_mem_fake_online(unsigned long pfn, unsigned long nr_pages)
  		if (PageDirty(page)) {
  			virtio_mem_clear_fake_offline(pfn + i, max_nr_pages,
  						      false);
-			generic_online_page(page, MAX_ORDER - 1);
+			generic_online_page(page, PAGES_PER_SECTION - 1);
  		} else {
  			virtio_mem_clear_fake_offline(pfn + i, max_nr_pages,
  						      true);

@@ -1228,7 +1228,7 @@ static void virtio_mem_online_page_cb(struct page *page, unsigned int order)
  		if (vm->in_sbm) {
  			/*
  			 * We exploit here that subblocks have at least
-			 * MAX_ORDER_NR_PAGES size/alignment - so we cannot
+			 * PAGES_PER_SECTION size/alignment - so we cannot
  			 * cross subblocks within one call.
  			 */
  			id = virtio_mem_phys_to_mb_id(addr);

@@ -2438,14 +2438,14 @@ static int virtio_mem_init(struct virtio_mem *vm)
  				      VIRTIO_MEM_DEFAULT_OFFLINE_THRESHOLD);
  
  	/*
-	 * We want subblocks to span at least MAX_ORDER_NR_PAGES and
+	 * We want subblocks to span at least PAGES_PER_SECTION and
  	 * pageblock_nr_pages pages. This:
  	 * - Simplifies our page onlining code (virtio_mem_online_page_cb)
  	 *   and fake page onlining code (virtio_mem_fake_online).
  	 * - Is required for now for alloc_contig_range() to work reliably -
  	 *   it doesn't properly handle smaller granularity on ZONE_NORMAL.
  	 */
-	sb_size = max_t(uint64_t, MAX_ORDER_NR_PAGES,
+	sb_size = max_t(uint64_t, PAGES_PER_SECTION,
  			pageblock_nr_pages) * PAGE_SIZE;
  	sb_size = max_t(uint64_t, vm->device_block_size, sb_size);