linux-kernel - Re: [PATCH v4] mm/vmalloc: replace BUG

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Date:   Wed, 1 Feb 2023 15:22:25 +0100
From:   Uladzislau Rezki <urezki@...il.com>
To:     Hyunmin Lee <hn.min.lee@...il.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Uladzislau Rezki <urezki@...il.com>,
        Christoph Hellwig <hch@...radead.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Gwan-gyeong Mun <gwan-gyeong.mun@...el.com>,
        Jeungwoo Yoo <casionwoo@...il.com>,
        Sangyun Kim <sangyun.kim@....ac.kr>,
        Mike Rapoport <rppt@...nel.org>,
        Christophe Leroy <christophe.leroy@...roup.eu>
Subject: Re: [PATCH v4] mm/vmalloc: replace BUG_ON to a simple if statement

On Wed, Feb 01, 2023 at 08:51:42PM +0900, Hyunmin Lee wrote:
> As per the coding standards, in the event of an abnormal condition that
> should not occur under normal circumstances, the kernel should attempt
> recovery and proceed with execution, rather than halting the machine.
> 
> Specifically, in the alloc_vmap_area() function, use a simple if()
> instead of using BUG_ON() halting the machine.
> 
> Co-Developed-by: Gwan-gyeong Mun <gwan-gyeong.mun@...el.com>
> Co-Developed-by: Jeungwoo Yoo <casionwoo@...il.com>
> Co-Developed-by: Sangyun Kim <sangyun.kim@....ac.kr>
> Signed-off-by: Hyunmin Lee <hn.min.lee@...il.com>
> Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@...el.com>
> Signed-off-by: Jeungwoo Yoo <casionwoo@...il.com>
> Signed-off-by: Sangyun Kim <sangyun.kim@....ac.kr>
> Cc: Hyeonggon Yoo <42.hyeyoo@...il.com>
> ---
> v1->v2 : Add commit description
> v2->v3 : Change WARN_ON() to if()
> v3->v4 : Use only one if() for three conditions
> ---
>  mm/vmalloc.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 74afa2208558..3b7e8856be35 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1587,9 +1587,8 @@ 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 (unlikely(!size || offset_in_page(size) || !is_power_of_2(align)))
> +		return ERR_PTR(-EINVAL);
>  
>  	if (unlikely(!vmap_initialized))
>  		return ERR_PTR(-EBUSY);
> -- 
> 2.25.1
> 
Makes sense to me.

Reviewed-by: Uladzislau Rezki (Sony) <urezki@...il.com>

--
Uladzislau Rezki