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Date:   Wed, 18 Apr 2018 12:43:32 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Chengguang Xu <cgxu519@gmx.com>
Cc:     linux-fsdevel@vger.kernel.org, dhowells@redhat.com,
        kstewart@linuxfoundation.org, gregkh@linuxfoundation.org,
        tglx@linutronix.de, pombredanne@nexb.com,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] hfsplus: fix potential refcnt problem of nls module
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        <1523948733-8537-2-git-send-email-cgxu519@gmx.com>
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On Tue, 17 Apr 2018 15:05:33 +0800 Chengguang Xu <cgxu519@gmx.com> wrote:

> When specifying nls option multiple times in a mount,
> current option parsing will cause inaccurate refcount of nls
> module. Hence, call unload_nls for previous one in this case.
> 
> --- a/fs/hfsplus/options.c
> +++ b/fs/hfsplus/options.c
> @@ -171,8 +171,10 @@ int hfsplus_parse_options(char *input, struct hfsplus_sb_info *sbi)
>  				return 0;
>  			}
>  			p = match_strdup(&args[0]);
> -			if (p)
> +			if (p) {
> +				unload_nls(sbi->nls);
>  				sbi->nls = load_nls(p);
> +			}
>  			if (!sbi->nls) {
>  				pr_err("unable to load nls mapping \"%s\"\n",
>  				       p);

Same problem as in [patch 1/2]