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

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Message-ID: <fe4337c7-0ede-dfa3-13ac-2cb225904ef4@csgroup.eu>
Date:   Wed, 1 Feb 2023 11:59:06 +0000
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Hyunmin Lee <hn.min.lee@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Uladzislau Rezki <urezki@...il.com>,
        Christoph Hellwig <hch@...radead.org>
CC:     "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.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>
Subject: Re: [PATCH v4] mm/vmalloc: replace BUG_ON to a simple if statement



Le 01/02/2023 à 12:51, Hyunmin Lee a écrit :
> 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>

Reviewed-by: Christophe Leroy <christophe.leroy@...roup.eu>

> ---
> 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);