From: Dan Carpenter <dan.carpenter-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
To: Yosry Ahmed <yosryahmed-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Cc: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>,
Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
Roman Gushchin
<roman.gushchin-fxUVXftIFDnyG1zEObXtfA@public.gmane.org>,
Shakeel Butt <shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
Muchun Song <songmuchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org>,
Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
Zefan Li <lizefan.x-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org>,
Shuah Khan <shuah-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
David Rientjes <rientjes-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
Andrew Morton
<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
Cgroups <cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Linux-MM <linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org>,
linux-kselftest-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
kernel-janitors-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH] selftests: memcg: uninitialized variable in test_memcg_reclaim()
Date: Wed, 20 Jul 2022 12:29:19 +0300 [thread overview]
Message-ID: <20220720092918.GD2316@kadam> (raw)
In-Reply-To: <CAJD7tkYCSY1C_iif4dxF9O3dAgZV4u8o9DFGsqeTyaq_FTT+mQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
On Tue, Jul 19, 2022 at 10:27:36AM -0700, Yosry Ahmed wrote:
>
> Nit: keep the cleanup_* naming for labels to make it obvious and to be
> consistent with the rest of the file (e.g. cleanup_free,
> cleanup_memcg, cleanup_file/cleanup_all). See
> test_memcg_subtree_control().
>
> I would honestly have one label to cleanup the memcg. Calling
> cg_destroy() on a non-existent memcg should be fine. rmdir() will just
> fail silently. All other tests do this and it's easier to read when we
> have fewer return paths. My advice would be cleanup_file and
> cleanup_memcg labels.
One error label handling is very bug prone. You always end up freeing
things which have not been initialized/allocated. Or dereferencing
pointers which are NULL. Or, since most kernel functions clean up
after themselves, you end up double freeing things.
regards,
dan carpenter
WARNING: multiple messages have this Message-ID (diff)
From: Dan Carpenter <dan.carpenter@oracle.com>
To: Yosry Ahmed <yosryahmed@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Shakeel Butt <shakeelb@google.com>,
Muchun Song <songmuchun@bytedance.com>, Tejun Heo <tj@kernel.org>,
Zefan Li <lizefan.x@bytedance.com>, Shuah Khan <shuah@kernel.org>,
David Rientjes <rientjes@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Cgroups <cgroups@vger.kernel.org>, Linux-MM <linux-mm@kvack.org>,
linux-kselftest@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [PATCH] selftests: memcg: uninitialized variable in test_memcg_reclaim()
Date: Wed, 20 Jul 2022 12:29:19 +0300 [thread overview]
Message-ID: <20220720092918.GD2316@kadam> (raw)
In-Reply-To: <CAJD7tkYCSY1C_iif4dxF9O3dAgZV4u8o9DFGsqeTyaq_FTT+mQ@mail.gmail.com>
On Tue, Jul 19, 2022 at 10:27:36AM -0700, Yosry Ahmed wrote:
>
> Nit: keep the cleanup_* naming for labels to make it obvious and to be
> consistent with the rest of the file (e.g. cleanup_free,
> cleanup_memcg, cleanup_file/cleanup_all). See
> test_memcg_subtree_control().
>
> I would honestly have one label to cleanup the memcg. Calling
> cg_destroy() on a non-existent memcg should be fine. rmdir() will just
> fail silently. All other tests do this and it's easier to read when we
> have fewer return paths. My advice would be cleanup_file and
> cleanup_memcg labels.
One error label handling is very bug prone. You always end up freeing
things which have not been initialized/allocated. Or dereferencing
pointers which are NULL. Or, since most kernel functions clean up
after themselves, you end up double freeing things.
regards,
dan carpenter
next prev parent reply other threads:[~2022-07-20 9:29 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-19 9:46 [PATCH] selftests: memcg: uninitialized variable in test_memcg_reclaim() Dan Carpenter
2022-07-19 9:46 ` Dan Carpenter
2022-07-19 17:27 ` Yosry Ahmed
2022-07-19 17:27 ` Yosry Ahmed
[not found] ` <CAJD7tkYCSY1C_iif4dxF9O3dAgZV4u8o9DFGsqeTyaq_FTT+mQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2022-07-20 9:29 ` Dan Carpenter [this message]
2022-07-20 9:29 ` Dan Carpenter
2022-07-20 17:35 ` Yosry Ahmed
2022-07-20 17:35 ` Yosry Ahmed
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