The value (HPAGE_PMD_NR - 1) is used often in the khugepaged code to
signify the limit of the max_ptes_* values. Add a define for this to
increase code readability and reuse.

Signed-off-by: Nico Pache <npache@redhat.com>
---
 mm/khugepaged.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index c362b3b2e08a..3dcce6018f20 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -85,6 +85,7 @@ static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
  *
  * Note that these are only respected if collapse was initiated by khugepaged.
  */
+#define COLLAPSE_MAX_PTES_LIMIT (HPAGE_PMD_NR - 1)
 unsigned int khugepaged_max_ptes_none __read_mostly;
 static unsigned int khugepaged_max_ptes_swap __read_mostly;
 static unsigned int khugepaged_max_ptes_shared __read_mostly;
@@ -252,7 +253,7 @@ static ssize_t max_ptes_none_store(struct kobject *kobj,
 	unsigned long max_ptes_none;
 
 	err = kstrtoul(buf, 10, &max_ptes_none);
-	if (err || max_ptes_none > HPAGE_PMD_NR - 1)
+	if (err || max_ptes_none > COLLAPSE_MAX_PTES_LIMIT)
 		return -EINVAL;
 
 	khugepaged_max_ptes_none = max_ptes_none;
@@ -277,7 +278,7 @@ static ssize_t max_ptes_swap_store(struct kobject *kobj,
 	unsigned long max_ptes_swap;
 
 	err  = kstrtoul(buf, 10, &max_ptes_swap);
-	if (err || max_ptes_swap > HPAGE_PMD_NR - 1)
+	if (err || max_ptes_swap > COLLAPSE_MAX_PTES_LIMIT)
 		return -EINVAL;
 
 	khugepaged_max_ptes_swap = max_ptes_swap;
@@ -303,7 +304,7 @@ static ssize_t max_ptes_shared_store(struct kobject *kobj,
 	unsigned long max_ptes_shared;
 
 	err  = kstrtoul(buf, 10, &max_ptes_shared);
-	if (err || max_ptes_shared > HPAGE_PMD_NR - 1)
+	if (err || max_ptes_shared > COLLAPSE_MAX_PTES_LIMIT)
 		return -EINVAL;
 
 	khugepaged_max_ptes_shared = max_ptes_shared;
@@ -384,7 +385,7 @@ int __init khugepaged_init(void)
 		return -ENOMEM;
 
 	khugepaged_pages_to_scan = HPAGE_PMD_NR * 8;
-	khugepaged_max_ptes_none = HPAGE_PMD_NR - 1;
+	khugepaged_max_ptes_none = COLLAPSE_MAX_PTES_LIMIT;
 	khugepaged_max_ptes_swap = HPAGE_PMD_NR / 8;
 	khugepaged_max_ptes_shared = HPAGE_PMD_NR / 2;
 
@@ -1869,7 +1870,7 @@ static enum scan_result collapse_file(struct mm_struct *mm, unsigned long addr,
 	bool is_shmem = shmem_file(file);
 
 	VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem);
-	VM_BUG_ON(start & (HPAGE_PMD_NR - 1));
+	VM_BUG_ON(start & (COLLAPSE_MAX_PTES_LIMIT));
 
 	result = alloc_charge_folio(&new_folio, mm, cc);
 	if (result != SCAN_SUCCEED)
@@ -2209,7 +2210,7 @@ static enum scan_result collapse_file(struct mm_struct *mm, unsigned long addr,
 	 * unwritten page.
 	 */
 	folio_mark_uptodate(new_folio);
-	folio_ref_add(new_folio, HPAGE_PMD_NR - 1);
+	folio_ref_add(new_folio, COLLAPSE_MAX_PTES_LIMIT);
 
 	if (is_shmem)
 		folio_mark_dirty(new_folio);
@@ -2303,7 +2304,7 @@ static enum scan_result hpage_collapse_scan_file(struct mm_struct *mm, unsigned
 	memset(cc->node_load, 0, sizeof(cc->node_load));
 	nodes_clear(cc->alloc_nmask);
 	rcu_read_lock();
-	xas_for_each(&xas, folio, start + HPAGE_PMD_NR - 1) {
+	xas_for_each(&xas, folio, start + COLLAPSE_MAX_PTES_LIMIT) {
 		if (xas_retry(&xas, folio))
 			continue;
 
-- 
2.53.0