[PATCH v2] mm/damon/vaddr: remove redundant RCU lock

[Igor Putko]

__damon_va_three_regions() is called only by damon_va_three_regions(),
which already holds mmap_read_lock(). Since mmap_read_lock() is held,
the maple tree and VMA list are protected from concurrent changes.
Remove the unnecessary rcu_read_lock() and rcu_read_unlock() calls.

Signed-off-by: Igor Putko <igorpetindev@xxxxxxxxx>
---
 mm/damon/tests/vaddr-kunit.h | 2 ++
 mm/damon/vaddr.c             | 2 --
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/damon/tests/vaddr-kunit.h b/mm/damon/tests/vaddr-kunit.h
index 563fbc7e3..70cb7825e 100644
--- a/mm/damon/tests/vaddr-kunit.h
+++ b/mm/damon/tests/vaddr-kunit.h
@@ -81,7 +81,9 @@ static void damon_test_three_regions_in_vmas(struct kunit *test)
 	if (__link_vmas(&mm.mm_mt, vmas, ARRAY_SIZE(vmas)))
 		kunit_skip(test, "Failed to create VMA tree");
 
+	rcu_read_lock();
 	__damon_va_three_regions(&mm, regions);
+	rcu_read_unlock();
 
 	KUNIT_EXPECT_EQ(test, 10ul, regions[0].start);
 	KUNIT_EXPECT_EQ(test, 25ul, regions[0].end);
diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
index d27147603..345b89b5d 100644
--- a/mm/damon/vaddr.c
+++ b/mm/damon/vaddr.c
@@ -84,7 +84,6 @@ static int __damon_va_three_regions(struct mm_struct *mm,
 	 * If this is too slow, it can be optimised to examine the maple
 	 * tree gaps.
 	 */
-	rcu_read_lock();
 	for_each_vma(vmi, vma) {
 		unsigned long gap;
 
@@ -105,7 +104,6 @@ static int __damon_va_three_regions(struct mm_struct *mm,
 next:
 		prev = vma;
 	}
-	rcu_read_unlock();
 
 	if (!sz_range(&second_gap) || !sz_range(&first_gap))
 		return -EINVAL;
-- 
2.47.3