FAILED: patch "[PATCH] mm/damon/tests/core-kunit: handle alloc failures on" failed to apply to 6.6-stable tree

FAILED: patch "[PATCH] mm/damon/tests/core-kunit: handle alloc failures on" failed to apply to 6.6-stable tree

[gregkh]

The patch below does not apply to the 6.6-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 <stable@vger.kernel.org>.

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-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x eded254cb69044bd4abde87394ea44909708d7c0
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026010533-uncounted-stuffing-5fb6@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

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

From eded254cb69044bd4abde87394ea44909708d7c0 Mon Sep 17 00:00:00 2001
From: SeongJae Park <sj@kernel.org>
Date: Sat, 1 Nov 2025 11:20:02 -0700
Subject: [PATCH] mm/damon/tests/core-kunit: handle alloc failures on
 damon_test_split_regions_of()

damon_test_split_regions_of() 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.

Link: https://lkml.kernel.org/r/20251101182021.74868-9-sj@kernel.org
Fixes: 17ccae8bb5c9 ("mm/damon: add kunit tests")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: David Gow <davidgow@google.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: <stable@vger.kernel.org>	[5.15+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index 98f2a3de7cea..10618cdd188e 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -278,15 +278,35 @@ static void damon_test_split_regions_of(struct kunit *test)
 	struct damon_target *t;
 	struct damon_region *r;
 
+	if (!c)
+		kunit_skip("ctx alloc fail");
 	t = damon_new_target();
+	if (!t) {
+		damon_destroy_ctx(c);
+		kunit_skip(test, "target alloc fail");
+	}
 	r = damon_new_region(0, 22);
+	if (!r) {
+		damon_destroy_ctx(c);
+		damon_free_target(t);
+		kunit_skip(test, "region alloc fail");
+	}
 	damon_add_region(r, t);
 	damon_split_regions_of(t, 2, DAMON_MIN_REGION);
 	KUNIT_EXPECT_LE(test, damon_nr_regions(t), 2u);
 	damon_free_target(t);
 
 	t = damon_new_target();
+	if (!t) {
+		damon_destroy_ctx(c);
+		kunit_skip(test, "second target alloc fail");
+	}
 	r = damon_new_region(0, 220);
+	if (!r) {
+		damon_destroy_ctx(c);
+		damon_free_target(t);
+		kunit_skip(test, "second region alloc fail");
+	}
 	damon_add_region(r, t);
 	damon_split_regions_of(t, 4, DAMON_MIN_REGION);
 	KUNIT_EXPECT_LE(test, damon_nr_regions(t), 4u);

[PATCH 6.6.y] mm/damon/tests/core-kunit: handle alloc failures on damon_test_split_regions_of()

[SeongJae Park]

damon_test_split_regions_of() 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.

Link: https://lkml.kernel.org/r/20251101182021.74868-9-sj@kernel.org
Fixes: 17ccae8bb5c9 ("mm/damon: add kunit tests")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: David Gow <davidgow@google.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: <stable@vger.kernel.org>	[5.15+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
(cherry picked from commit eded254cb69044bd4abde87394ea44909708d7c0)
Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/core-test.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/mm/damon/core-test.h b/mm/damon/core-test.h
index 6cc8b245586d..de7011b5d1e7 100644
--- a/mm/damon/core-test.h
+++ b/mm/damon/core-test.h
@@ -216,15 +216,35 @@ static void damon_test_split_regions_of(struct kunit *test)
 	struct damon_target *t;
 	struct damon_region *r;
 
+	if (!c)
+		kunit_skip(test, "ctx alloc fail");
 	t = damon_new_target();
+	if (!t) {
+		damon_destroy_ctx(c);
+		kunit_skip(test, "target alloc fail");
+	}
 	r = damon_new_region(0, 22);
+	if (!r) {
+		damon_destroy_ctx(c);
+		damon_free_target(t);
+		kunit_skip(test, "region alloc fail");
+	}
 	damon_add_region(r, t);
 	damon_split_regions_of(t, 2);
 	KUNIT_EXPECT_LE(test, damon_nr_regions(t), 2u);
 	damon_free_target(t);
 
 	t = damon_new_target();
+	if (!t) {
+		damon_destroy_ctx(c);
+		kunit_skip(test, "second target alloc fail");
+	}
 	r = damon_new_region(0, 220);
+	if (!r) {
+		damon_destroy_ctx(c);
+		damon_free_target(t);
+		kunit_skip(test, "second region alloc fail");
+	}
 	damon_add_region(r, t);
 	damon_split_regions_of(t, 4);
 	KUNIT_EXPECT_LE(test, damon_nr_regions(t), 4u);
-- 
2.47.3

Re: FAILED: patch "[PATCH] mm/damon/tests/core-kunit: handle alloc failures on" failed to apply to 6.6-stable tree

[SeongJae Park]

On Mon, 05 Jan 2026 12:05:33 +0100 <gregkh@linuxfoundation.org> wrote:

> 
> The patch below does not apply to the 6.6-stable tree.
[...]
> ------------------ original commit in Linus's tree ------------------
> 
> >From eded254cb69044bd4abde87394ea44909708d7c0 Mon Sep 17 00:00:00 2001
> From: SeongJae Park <sj@kernel.org>
> Date: Sat, 1 Nov 2025 11:20:02 -0700
> Subject: [PATCH] mm/damon/tests/core-kunit: handle alloc failures on
>  damon_test_split_regions_of()
> 
> damon_test_split_regions_of() 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.
> 
> Link: https://lkml.kernel.org/r/20251101182021.74868-9-sj@kernel.org
> Fixes: 17ccae8bb5c9 ("mm/damon: add kunit tests")
> Signed-off-by: SeongJae Park <sj@kernel.org>
> Cc: Brendan Higgins <brendan.higgins@linux.dev>
> Cc: David Gow <davidgow@google.com>
> Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
> Cc: <stable@vger.kernel.org>	[5.15+]
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> 
> diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
> index 98f2a3de7cea..10618cdd188e 100644
> --- a/mm/damon/tests/core-kunit.h
> +++ b/mm/damon/tests/core-kunit.h
> @@ -278,15 +278,35 @@ static void damon_test_split_regions_of(struct kunit *test)
>  	struct damon_target *t;
>  	struct damon_region *r;
>  
> +	if (!c)
> +		kunit_skip("ctx alloc fail");

FYI, the above diff breaks build because kunit_skip() receives two arguments.
Yes, the upstreamed patch is broken.  But, it was not noticed because a patch
[1] silently fixing the issue has merged into the mainline together, as a part
of the same patch series.

My ported patch that just sent as a reply to this mail fixes this together.

[1] 80d725f96c44 ("mm/damon/tests/core-kunit: remove unused ctx in damon_test_split_regions_of()")


Thanks,
SJ

[...]