linux-kernel - [PATCH 1/2] mm: remove redundant check in page_vma_mapped

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Message-Id: <20230704213932.1339204-2-shikemeng@huaweicloud.com>
Date:   Wed,  5 Jul 2023 05:39:31 +0800
From:   Kemeng Shi <shikemeng@...weicloud.com>
To:     akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Cc:     shikemeng@...weicloud.com
Subject: [PATCH 1/2] mm: remove redundant check in page_vma_mapped_walk

For PVMW_SYNC case, we always take pte lock when get first pte of
PTE-mapped THP in map_pte and hold it until:
1. scan of pmd range finished or
2. scan of user input range finished or
3. user stop walk with page_vma_mapped_walk_done.
In each case. pte lock will not be freed during middle scan of PTE-mapped
THP.

Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>
---
 mm/page_vma_mapped.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
index 4e448cfbc6ef..83858758e239 100644
--- a/mm/page_vma_mapped.c
+++ b/mm/page_vma_mapped.c
@@ -275,10 +275,6 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
 				goto restart;
 			}
 			pvmw->pte++;
-			if ((pvmw->flags & PVMW_SYNC) && !pvmw->ptl) {
-				pvmw->ptl = pte_lockptr(mm, pvmw->pmd);
-				spin_lock(pvmw->ptl);
-			}
 		} while (pte_none(*pvmw->pte));
 
 		if (!pvmw->ptl) {
-- 
2.30.0