FAILED: patch "[PATCH] mm/damon/tests/core-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 3d443dd29a1db7efa587a4bb0c06a497e13ca9e4
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026010519-cathedral-cuddle-c32b@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From 3d443dd29a1db7efa587a4bb0c06a497e13ca9e4 Mon Sep 17 00:00:00 2001
From: SeongJae Park <[email protected]>
Date: Sat, 1 Nov 2025 11:20:00 -0700
Subject: [PATCH] mm/damon/tests/core-kunit: handle alloc failures on
damon_test_merge_two()

damon_test_merge_two() 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 f5f3152cb8df..e8219fd23318 100644
@@ -188,11 +188,21 @@ static void damon_test_merge_two(struct kunit *test)
 	int i;
 
 	t = damon_new_target();
+	if (!t)
+		kunit_skip(test, "target alloc fail");
 	r = damon_new_region(0, 100);
+	if (!r) {
+		damon_free_target(t);
+		kunit_skip(test, "region alloc fail");
+	}
 	r->nr_accesses = 10;
 	r->nr_accesses_bp = 100000;
 	damon_add_region(r, t);
 	r2 = damon_new_region(100, 300);
+	if (!r2) {
+		damon_free_target(t);
+		kunit_skip(test, "second region alloc fail");
+	}
 	r2->nr_accesses = 20;
 	r2->nr_accesses_bp = 200000;
 	damon_add_region(r2, t);

damon_test_merge_two() 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/core-test.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

index 7008c3735e99..d22c86d5148b 100644
@@ -144,10 +144,20 @@ static void damon_test_merge_two(struct kunit *test)
 	int i;
 
 	t = damon_new_target(42);
+	if (!t)
+		kunit_skip(test, "target alloc fail");
 	r = damon_new_region(0, 100);
+	if (!r) {
+		damon_free_target(t);
+		kunit_skip(test, "region alloc fail");
+	}
 	r->nr_accesses = 10;
 	damon_add_region(r, t);
 	r2 = damon_new_region(100, 300);
+	if (!r2) {
+		damon_free_target(t);
+		kunit_skip(test, "second region alloc fail");
+	}
 	r2->nr_accesses = 20;
 	damon_add_region(r2, t);
 

2.47.3