Date:   Mon, 30 Jan 2023 12:14:04 +0200
From:   Mike Rapoport <rppt@kernel.org>
To:     Hyunmin Lee <hn.min.lee@gmail.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Uladzislau Rezki <urezki@gmail.com>,
        Christoph Hellwig <hch@infradead.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] replace BUG_ON to WARN_ON
Message-ID: <Y9eYbPuq5Nw9Njxf@kernel.org>
References: <20230127115844.GA1124261@min-iamroot>
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In-Reply-To: <20230127115844.GA1124261@min-iamroot>
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Hi,

On Fri, Jan 27, 2023 at 08:58:44PM +0900, Hyunmin Lee wrote:
> Replace unnacessary BUG_ON to WARN_ON. These BUG_ONs verify aruguments of a function. Thus, the WARN_ONs return an EINVAL error when their condition is true.

Some users enable panic_on_warn, so for them WARN_ON will still crash a
machine.

I think a simple if() will be sufficient.
 
> Co-Developed-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
> Co-Developed-by: Jeungwoo Yoo <casionwoo@gmail.com>
> Co-Developed-by: Sangyun Kim <sangyun.kim@snu.ac.kr>
> Signed-off-by: Hyunmin Lee <hn.min.lee@gmail.com>
> Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
> Signed-off-by: Jeungwoo Yoo <casionwoo@gmail.com>
> Signed-off-by: Sangyun Kim <sangyun.kim@snu.ac.kr>
> Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
> ---
>  mm/vmalloc.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 74afa2208558..9f9dba3132c5 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1587,9 +1587,14 @@ static struct vmap_area *alloc_vmap_area(unsigned long size,
>  	int purged = 0;
>  	int ret;
>  
> -	BUG_ON(!size);
> -	BUG_ON(offset_in_page(size));
> -	BUG_ON(!is_power_of_2(align));
> +	if (WARN_ON(!size))
> +		return ERR_PTR(-EINVAL);
> +
> +	if (WARN_ON(offset_in_page(size)))
> +		return ERR_PTR(-EINVAL);
> +
> +	if (WARN_ON(!is_power_of_2(align)))
> +		return ERR_PTR(-EINVAL);
>  
>  	if (unlikely(!vmap_initialized))
>  		return ERR_PTR(-EBUSY);
> -- 
> 2.25.1
> 
> 

-- 
Sincerely yours,
Mike.