mm: thp: remove redundant pgtable check in set_huge_zero_page()

Commit Message

Qi Zheng Aug. 18, 2022, 8:27 a.m. UTC

When the pgtable is NULL in the set_huge_zero_page(), we should
not increment the count of PTE page table pages by calling
mm_inc_nr_ptes(). Otherwise we may receive the following warning
when the mm exits:

	BUG: non-zero pgtables_bytes on freeing mm

Now we can't observe the above warning since only
do_huge_pmd_anonymous_page() invokes set_huge_zero_page() and the
pgtable can not be NULL.

Therefore, instead of moving mm_inc_nr_ptes() to the non-NULL
branch of pgtable, it is better to remove the redundant pgtable
check directly.

Signed-off-by: Qi Zheng <[e-mail]>
---
 mm/huge_memory.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Patch

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 83c47a989260..655da0b4fea0 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -770,8 +770,7 @@  static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
 		return;
 	entry = mk_pmd(zero_page, vma->vm_page_prot);
 	entry = pmd_mkhuge(entry);
-	if (pgtable)
-		pgtable_trans_huge_deposit(mm, pmd, pgtable);
+	pgtable_trans_huge_deposit(mm, pmd, pgtable);
 	set_pmd_at(mm, haddr, pmd, entry);
 	mm_inc_nr_ptes(mm);
 }