[RFC PATCH 3/3] mm/mincore: avoid touching the PTL

[Kairui Song <ryncsn@gmail.com>]

From: Kairui Song <kasong@tencent.com>

mincore only interested in the existence of a page, which is a
changing state by nature, locking and making it stable is not needed.
And now neither mincore_page or mincore_swap requires PTL, this PTL
locking can be dropped.

Signed-off-by: Kairui Song <kasong@tencent.com>
---
 mm/mincore.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/mincore.c b/mm/mincore.c
index 1ac53acac239..cc4460aba1f9 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -153,13 +153,13 @@ static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 		goto out;
 	}
 
-	ptep = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
+	ptep = pte_offset_map(pmd, addr);
 	if (!ptep) {
 		walk->action = ACTION_AGAIN;
 		return 0;
 	}
 	for (; addr != end; ptep += step, addr += step * PAGE_SIZE) {
-		pte_t pte = ptep_get(ptep);
+		pte_t pte = ptep_get_lockless(ptep);
 
 		step = 1;
 		/* We need to do cache lookup too for pte markers */
@@ -192,7 +192,7 @@ static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 		}
 		vec += step;
 	}
-	pte_unmap_unlock(ptep - 1, ptl);
+	pte_unmap(ptep - 1);
 out:
 	walk->private += nr;
 	cond_resched();
-- 
2.50.1