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[2001:b400:e2a7:952f:2dd6:3028:1fcb:8aa4]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-81fa12b5209sm9515648b3a.63.2026.01.19.06.22.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Jan 2026 06:22:29 -0800 (PST) From: Nick Huang To: linux-kernel@vger.kernel.org Cc: Ilya Dryomov , Geert Uytterhoeven , David Gow , Nick Huang , David Sterba , Chuck Lever , Chaohai Chen , paladin@ntub.edu.tw, kusogame68@gmail.com, n1136402@ntub.edu.tw Subject: [PATCH] kunit: add cross-CPU alloc/free test for kmem_cache Date: Mon, 19 Jan 2026 14:22:22 +0000 Message-ID: <20260119142222.4958-1-sef1548@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add a KUnit test to verify that kmem_cache objects can be allocated on one CPU and freed on another. This ensures SLAB/SLUB correctly handles cross-CPU frees via per-CPU caches and remote free lists. The test: - Allocates an object on CPU0 - Frees it on CPU1 - Allocates again to ensure cache still works Signed-off-by: Nick Huang --- lib/tests/slub_kunit.c | 64 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 64 insertions(+) diff --git a/lib/tests/slub_kunit.c b/lib/tests/slub_kunit.c index 848b682a2..c556723d4 100644 --- a/lib/tests/slub_kunit.c +++ b/lib/tests/slub_kunit.c @@ -7,6 +7,8 @@ #include #include #include +#include +#include #include "../mm/slab.h" =20 static struct kunit_resource resource; @@ -290,7 +292,68 @@ static void test_krealloc_redzone_zeroing(struct kunit= *test) kasan_enable_current(); kmem_cache_destroy(s); } +struct cache_obj { + struct kmem_cache *cache; + void *obj; + struct kunit *test; +}; + +/* CPU execute alloc */ +static void alloc_obj_fn(void *arg) +{ + struct cache_obj *co =3D arg; + + co->obj =3D kmem_cache_alloc(co->cache, GFP_KERNEL); + KUNIT_ASSERT_NOT_NULL(co->test, co->obj); +} =20 +/* CPU execute free */ +static void free_obj_fn(void *arg) +{ + struct cache_obj *co =3D arg; + kmem_cache_free(co->cache, co->obj); +} + +static void test_cross_cpu_alloc_free(struct kunit *test) +{ + struct kmem_cache *cache; + struct cache_obj co; + int cpu0, cpu1; + + if ( num_online_cpus() < 2) + kunit_skip(test, "need >=3D 2 CPUs"); + + /* Create a test cache */ + cache =3D kmem_cache_create("cross_cpu_test", + 64, 0, SLAB_DEBUG_FLAGS, NULL); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, cache); + + /* Pick two different online CPUs */ + cpu0 =3D cpumask_first(cpu_online_mask); + cpu1 =3D cpumask_next(cpu0, cpu_online_mask); + + /* Fill the struct to pass as argument */ + co.cache =3D cache; + co.obj =3D NULL; + co.test =3D test; + + /* CPU0 alloc */ + KUNIT_ASSERT_EQ(test, smp_call_function_single(cpu0, + alloc_obj_fn, + &co, 1), 0); + + /* CPU1 free */ + KUNIT_ASSERT_EQ(test, smp_call_function_single(cpu1, + free_obj_fn, + &co, 1), 0); + + /* Allocate again (any CPU) */ + co.obj =3D kmem_cache_alloc(cache, GFP_KERNEL); + KUNIT_ASSERT_NOT_NULL(test, co.obj); + + kmem_cache_free(cache, co.obj); + kmem_cache_destroy(cache); +} static int test_init(struct kunit *test) { slab_errors =3D 0; @@ -315,6 +378,7 @@ static struct kunit_case test_cases[] =3D { KUNIT_CASE(test_kfree_rcu_wq_destroy), KUNIT_CASE(test_leak_destroy), KUNIT_CASE(test_krealloc_redzone_zeroing), + KUNIT_CASE(test_cross_cpu_alloc_free), {} }; =20 --=20 2.43.0