FAILED: patch "[PATCH] mm/damon/tests/vaddr-kunit: handle alloc failures on" failed to apply to 5.15-stable tree

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 0a63a0e7570b9b2631dfb8d836dc572709dce39e
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026010513-quickness-paging-fee4@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 0a63a0e7570b9b2631dfb8d836dc572709dce39e Mon Sep 17 00:00:00 2001
From: SeongJae Park <[email protected]>
Date: Sat, 1 Nov 2025 11:20:13 -0700
Subject: [PATCH] mm/damon/tests/vaddr-kunit: handle alloc failures on
damon_test_split_evenly_succ()

damon_test_split_evenly_succ() is assuming all dynamic memory allocation in it will succeed. Those are indeed likely in the real use cases since those allocations are too small to fail, but theoretically those could fail. In the case, inappropriate memory access can happen. Fix it by appropriately cleanup pre-allocated memory and skip the execution of the remaining tests in the failure cases.

index 1b0f21c2e376..30dc5459f1d2 100644
@@ -284,10 +284,17 @@ static void damon_test_split_evenly_succ(struct kunit *test,
 	unsigned long start, unsigned long end, unsigned int nr_pieces)
 {
 	struct damon_target *t = damon_new_target();
-	struct damon_region *r = damon_new_region(start, end);
+	struct damon_region *r;
 	unsigned long expected_width = (end - start) / nr_pieces;
 	unsigned long i = 0;
 
+	if (!t)
+		kunit_skip(test, "target alloc fail");
+	r = damon_new_region(start, end);
+	if (!r) {
+		damon_free_target(t);
+		kunit_skip(test, "region alloc fail");
+	}
 	damon_add_region(r, t);
 	KUNIT_EXPECT_EQ(test,
 			damon_va_evenly_split_region(t, r, nr_pieces), 0);

damon_test_split_evenly_succ() is assuming all dynamic memory allocation in it will succeed. Those are indeed likely in the real use cases since those allocations are too small to fail, but theoretically those could fail. In the case, inappropriate memory access can happen. Fix it by appropriately cleanup pre-allocated memory and skip the execution of the remaining tests in the failure cases.

---
 mm/damon/vaddr-test.h | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

index 5531766ff09f..b23073e52a95 100644
@@ -275,10 +275,17 @@ static void damon_test_split_evenly_succ(struct kunit *test,
 	unsigned long start, unsigned long end, unsigned int nr_pieces)
 {
 	struct damon_target *t = damon_new_target(42);
-	struct damon_region *r = damon_new_region(start, end);
+	struct damon_region *r;
 	unsigned long expected_width = (end - start) / nr_pieces;
 	unsigned long i = 0;
 
+	if (!t)
+		kunit_skip(test, "target alloc fail");
+	r = damon_new_region(start, end);
+	if (!r) {
+		damon_free_target(t);
+		kunit_skip(test, "region alloc fail");
+	}
 	damon_add_region(r, t);
 	KUNIT_EXPECT_EQ(test,
 			damon_va_evenly_split_region(t, r, nr_pieces), 0);

2.47.3