[PATCH] mm: pgtable: Ensure pml spinlock gets unlock

[I Hsin Cheng <richard120310@gmail.com>]

When !start_pte is true, the "pml" spinlock is still being holded and
the branch "out_pte" is taken. If "ptl" is equal to "pml", the lock
"pml" will still be locked when the function returns.

It'll be better to set a new branch "out_pte" and jump to it when
!start_pte is true at the first place, therefore no additional check for
"start_pte" or "ptl != pml" is needed, simply unlock "pml" and return.

Signed-off-by: I Hsin Cheng <richard120310@gmail.com>
---
 mm/pt_reclaim.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/mm/pt_reclaim.c b/mm/pt_reclaim.c
index 7e9455a18aae..163e38f1728d 100644
--- a/mm/pt_reclaim.c
+++ b/mm/pt_reclaim.c
@@ -43,7 +43,7 @@ void try_to_free_pte(struct mm_struct *mm, pmd_t *pmd, unsigned long addr,
 	pml = pmd_lock(mm, pmd);
 	start_pte = pte_offset_map_rw_nolock(mm, pmd, addr, &pmdval, &ptl);
 	if (!start_pte)
-		goto out_ptl;
+		goto out_pte;
 	if (ptl != pml)
 		spin_lock_nested(ptl, SINGLE_DEPTH_NESTING);
 
@@ -68,4 +68,8 @@ void try_to_free_pte(struct mm_struct *mm, pmd_t *pmd, unsigned long addr,
 		pte_unmap_unlock(start_pte, ptl);
 	if (ptl != pml)
 		spin_unlock(pml);
+	return;
+
+out_pte:
+	spin_unlock(pml);
 }
-- 
2.43.0