mm/damon: replace pmd_huge() with pmd_trans_huge() for THP

pmd_huge() is usually used to indicate a pmd level hugetlb.  However a pmd
mapped huge page can only be THP in damon_mkold_pmd_entry() or
damon_young_pmd_entry(), so replace pmd_huge() with pmd_trans_huge() in
this case to make the code more readable according to the discussion [1].

[1] https://lore.kernel.org/all/098c1480-416d-bca9-cedb-ca495df69b64@linux.alibaba.com/

Link: https://lkml.kernel.org/r/a9e010ca5d299e18d740c7c52290ecb6a014dde6.1660805030.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/damon/vaddr.c

@@ -302,14 +302,14 @@ static int damon_mkold_pmd_entry(pmd_t *pmd, unsigned long addr,
 	pte_t *pte;
 	spinlock_t *ptl;
 
-	if (pmd_huge(*pmd)) {
+	if (pmd_trans_huge(*pmd)) {
 		ptl = pmd_lock(walk->mm, pmd);
 		if (!pmd_present(*pmd)) {
 			spin_unlock(ptl);
 			return 0;
 		}
 
-		if (pmd_huge(*pmd)) {
+		if (pmd_trans_huge(*pmd)) {
 			damon_pmdp_mkold(pmd, walk->mm, addr);
 			spin_unlock(ptl);
 			return 0;
@@ -434,14 +434,14 @@ static int damon_young_pmd_entry(pmd_t *pmd, unsigned long addr,
 	struct damon_young_walk_private *priv = walk->private;
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
-	if (pmd_huge(*pmd)) {
+	if (pmd_trans_huge(*pmd)) {
 		ptl = pmd_lock(walk->mm, pmd);
 		if (!pmd_present(*pmd)) {
 			spin_unlock(ptl);
 			return 0;
 		}
 
-		if (!pmd_huge(*pmd)) {
+		if (!pmd_trans_huge(*pmd)) {
 			spin_unlock(ptl);
 			goto regular_page;
 		}