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Date:   Thu, 18 Aug 2022 08:25:11 +0200
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Axel Rasmussen <axelrasmussen@google.com>
Cc:     Alexander Viro <viro@zeniv.linux.org.uk>,
        Andrew Morton <akpm@linux-foundation.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "Dmitry V . Levin" <ldv@altlinux.org>,
        Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org>,
        Hugh Dickins <hughd@google.com>, Jan Kara <jack@suse.cz>,
        Jonathan Corbet <corbet@lwn.net>,
        Mel Gorman <mgorman@techsingularity.net>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Mike Rapoport <rppt@kernel.org>, Nadav Amit <namit@vmware.com>,
        Peter Xu <peterx@redhat.com>, Shuah Khan <shuah@kernel.org>,
        Suren Baghdasaryan <surenb@google.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        zhangyi <yi.zhang@huawei.com>, linux-doc@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-kselftest@vger.kernel.org, linux-mm@kvack.org,
        linux-security-module@vger.kernel.org,
        Mike Rapoport <rppt@linux.ibm.com>
Subject: Re: [PATCH v6 2/5] userfaultfd: add /dev/userfaultfd for fine
 grained access control
Message-ID: <Yv3bRwh/M8WVkQBs@kroah.com>
References: <20220817214728.489904-1-axelrasmussen@google.com>
 <20220817214728.489904-3-axelrasmussen@google.com>
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On Wed, Aug 17, 2022 at 02:47:25PM -0700, Axel Rasmussen wrote:
>  static int __init userfaultfd_init(void)
>  {
> +	WARN_ON(misc_register(&userfaultfd_misc));

Please no.

Spell this out and properly error out if there is an issue:
	int ret;

	ret = misc_register(&userfaultfd_misc);
	if (ret)
		return ret;

Handle issues properly, don't paper over them with WARN_ON().

thanks,

greg k-h