Date: Thu, 22 Dec 2016 11:56:37 +0300
From: Vladimir Davydov <vdavydov@tarantool.org>
To: Greg Thelen <gthelen@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>, Christoph Lameter <cl@linux.com>,
        Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>, kasan-dev@googlegroups.com,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] kasan: add memcg kmem_cache test
Message-ID: <20161222085637.GB3494@esperanza>
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On Tue, Dec 20, 2016 at 10:11:02AM -0800, Greg Thelen wrote:
> Make a kasan test which uses a SLAB_ACCOUNT slab cache.  If the test is
> run within a non default memcg, then it uncovers the bug fixed by
> "kasan: drain quarantine of memcg slab objects"[1].
> 
> If run without fix [1] it shows "Slab cache still has objects", and the
> kmem_cache structure is leaked.
> Here's an unpatched kernel test:
> $ dmesg -c > /dev/null
> $ mkdir /sys/fs/cgroup/memory/test
> $ echo $$ > /sys/fs/cgroup/memory/test/tasks
> $ modprobe test_kasan 2> /dev/null
> $ dmesg | grep -B1 still
> [ 123.456789] kasan test: memcg_accounted_kmem_cache allocate memcg accounted object
> [ 124.456789] kmem_cache_destroy test_cache: Slab cache still has objects
> 
> Kernels with fix [1] don't have the "Slab cache still has objects"
> warning or the underlying leak.
> 
> The new test runs and passes in the default (root) memcg, though in the
> root memcg it won't uncover the problem fixed by [1].
> 
> Signed-off-by: Greg Thelen <gthelen@google.com>

Reviewed-by: Vladimir Davydov <vdavydov.dev@gmail.com>