[PATCH v3 08/15] mm/pte_ref: initialize the refcount of the withdrawn PTE page table page

[Qi Zheng <zhengqi.arch@bytedance.com>]

When we split the PMD-mapped THP to the PTE-mapped THP, we should
initialize the refcount of the withdrawn PTE page table page to
HPAGE_PMD_NR, which ensures that we can release the PTE page table
page when it is free(the refcount is 0).

Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
---
 mm/pgtable-generic.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index 4e640baf9794..523053e09dfa 100644
--- a/mm/pgtable-generic.c
+++ b/mm/pgtable-generic.c
@@ -186,6 +186,7 @@ pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
 							  struct page, lru);
 	if (pmd_huge_pte(mm, pmdp))
 		list_del(&pgtable->lru);
+	pte_ref_init(pgtable, pmdp, HPAGE_PMD_NR);
 	return pgtable;
 }
 #endif
-- 
2.11.0