[PATCH] mm/damon/vaddr: protect vma traversal in __damon_va_thre_regions() with rcu read lock

[SeongJae Park]

From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>

Traversing VMAs of a given maple tree should be protected by rcu read
lock.  However, __damon_va_three_regions() is not doing the protection.
Hold the lock.

Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Closes: https://lore.kernel.org/b83651a0-5b24-4206-b860-cb54ffdf209b@xxxxxxxxxxxx
Fixes: d0cf3dd47f0d ("damon: convert __damon_va_three_regions to use the VMA iterator")
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Tested-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
---
 mm/damon/vaddr.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
index b0e8b361891d..08cfd22b5249 100644
--- a/mm/damon/vaddr.c
+++ b/mm/damon/vaddr.c
@@ -126,6 +126,7 @@ 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;
 
@@ -146,6 +147,7 @@ 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;
-- 
2.39.2