linux-kernel - [PATCH] mm/damon/vaddr: protect vma traversal in __damon_va_thre

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Message-Id: <20240905001204.1481-1-sj@kernel.org>
Date: Wed,  4 Sep 2024 17:12:04 -0700
From: SeongJae Park <sj@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: "Liam R. Howlett" <Liam.Howlett@...cle.com>,
	"Matthew Wilcox (Oracle)" <willy@...radead.org>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	David Hildenbrand <david@...hat.com>,
	damon@...ts.linux.dev,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Guenter Roeck <linux@...ck-us.net>,
	SeongJae Park <sj@...nel.org>
Subject: [PATCH] mm/damon/vaddr: protect vma traversal in __damon_va_thre_regions() with rcu read lock

From: "Liam R. Howlett" <Liam.Howlett@...cle.com>

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@...ck-us.net>
Closes: https://lore.kernel.org/b83651a0-5b24-4206-b860-cb54ffdf209b@roeck-us.net
Fixes: d0cf3dd47f0d ("damon: convert __damon_va_three_regions to use the VMA iterator")
Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
Tested-by: Guenter Roeck <linux@...ck-us.net>
Signed-off-by: SeongJae Park <sj@...nel.org>
---
 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