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[90.233.216.8]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-530de3e313csm1030750e87.55.2024.08.09.09.23.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Aug 2024 09:23:52 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Fri, 9 Aug 2024 18:23:48 +0200 To: Vlastimil Babka , "Paul E. McKenney" Cc: "Paul E. McKenney" , Joel Fernandes , Josh Triplett , Boqun Feng , Christoph Lameter , David Rientjes , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Julia Lawall , Jakub Kicinski , "Jason A. Donenfeld" , "Uladzislau Rezki (Sony)" , Andrew Morton , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcu@vger.kernel.org, Alexander Potapenko , Marco Elver , Dmitry Vyukov , kasan-dev@googlegroups.com, Jann Horn , Mateusz Guzik Subject: Re: [PATCH v2 7/7] kunit, slub: add test_kfree_rcu() and test_leak_destroy() Message-ID: References: <20240807-b4-slab-kfree_rcu-destroy-v2-0-ea79102f428c@suse.cz> <20240807-b4-slab-kfree_rcu-destroy-v2-7-ea79102f428c@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240807-b4-slab-kfree_rcu-destroy-v2-7-ea79102f428c@suse.cz> X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: C7D6EC0005 X-Stat-Signature: zq8bmrahcswc3c1saszghu43cs63rwpf X-Rspam-User: X-HE-Tag: 1723220638-153777 X-HE-Meta: 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 E+1DkLRT z8HRKXmzUC1BGsiTEfiPoeWbtLlIDs9Lp5vm0fEBll7Q0obFyfb84TvDVCqBAkbvNemXAd85mYDemPxfLyy/zA1uyRNM0TbLW0DE+6qLoCZvXxfgu8QlvlQmRXVPNWRj1dnT3wjjpMVhUX1jLYDd7wL4ZIO9ft8KFEdR5oVfIVQ5rUMDLwWqgvyvK+cANeBldFZurahPlbdhhtqxs2wupQrD1e88cfG85r5QSG4qgNC+yiNLxR/ptAqW6Ldc5y4mV5JD13ATWkfe9IDH56/D4Llam/AY/pG1wOoAbFMHiXjm7iT0V5Oom9QBwqrAI9Lvfx4whWtDHEElGtdG2pnQsMVxQ20LMFmxoa0AeQdbs9T847S2Abvl6CylrtpTeQ0rs1mToSXOiMPGBLI0B6SzmymF/YUPwtmxZgsGzwxyOY2MjRgVZKJ9e3YmoA1Eg/+2/i7+Y8PZO7mQWIy6Oynz5TjnnYUupuSxMNeoRMutoMYLVW2Y= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Aug 07, 2024 at 12:31:20PM +0200, Vlastimil Babka wrote: > Add a test that will create cache, allocate one object, kfree_rcu() it > and attempt to destroy it. As long as the usage of kvfree_rcu_barrier() > in kmem_cache_destroy() works correctly, there should be no warnings in > dmesg and the test should pass. > > Additionally add a test_leak_destroy() test that leaks an object on > purpose and verifies that kmem_cache_destroy() catches it. > > Signed-off-by: Vlastimil Babka > --- > lib/slub_kunit.c | 31 +++++++++++++++++++++++++++++++ > 1 file changed, 31 insertions(+) > > diff --git a/lib/slub_kunit.c b/lib/slub_kunit.c > index e6667a28c014..6e3a1e5a7142 100644 > --- a/lib/slub_kunit.c > +++ b/lib/slub_kunit.c > @@ -5,6 +5,7 @@ > #include > #include > #include > +#include > #include "../mm/slab.h" > > static struct kunit_resource resource; > @@ -157,6 +158,34 @@ static void test_kmalloc_redzone_access(struct kunit *test) > kmem_cache_destroy(s); > } > > +struct test_kfree_rcu_struct { > + struct rcu_head rcu; > +}; > + > +static void test_kfree_rcu(struct kunit *test) > +{ > + struct kmem_cache *s = test_kmem_cache_create("TestSlub_kfree_rcu", > + sizeof(struct test_kfree_rcu_struct), > + SLAB_NO_MERGE); > + struct test_kfree_rcu_struct *p = kmem_cache_alloc(s, GFP_KERNEL); > + > + kfree_rcu(p, rcu); > + kmem_cache_destroy(s); > + > + KUNIT_EXPECT_EQ(test, 0, slab_errors); > +} > + > Thank you for this test case! I used this series to test _more_ the barrier and came to conclusion that it is not enough, i.e. i had to extend it to something like below: + snprintf(name, sizeof(name), "test-slub-%d", current->pid); + + for (i = 0; i < test_loop_count; i++) { + s = test_kmem_cache_create(name, sizeof(struct test_kfree_rcu_struct), + SLAB_NO_MERGE); + + if (!s) + BUG(); + + get_random_bytes(&nr_to_alloc, sizeof(nr_to_alloc)); + nr_to_alloc = nr_to_alloc % 1000000; + INIT_LIST_HEAD(&local_head); + + for (j = 0; j < nr_to_alloc; j++) { + p = kmem_cache_alloc(s, GFP_KERNEL); + + if (p) + list_add(&p->list, &local_head); + } + + list_for_each_entry_safe(p, n, &local_head, list) + kfree_rcu(p, rcu); + + kmem_cache_destroy(s); + } by using this(~11 parallel jobs) i could trigger a warning that a freed cache still has some objects and i have already figured out why. I will send a v2 of barrier implementation with a fix. Thanks! -- Uladzislau Rezki