linux-kernel - Re: [PATCH 4/4] hugetlb: Remove redundant VM_BUG_ON() in add_reservation_in

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Date:   Fri, 22 Oct 2021 16:57:15 -0700
From:   Mike Kravetz <mike.kravetz@...cle.com>
To:     Baolin Wang <baolin.wang@...ux.alibaba.com>,
        akpm@...ux-foundation.org
Cc:     mhocko@...nel.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/4] hugetlb: Remove redundant VM_BUG_ON() in
 add_reservation_in_range()

On 10/20/21 11:31 PM, Baolin Wang wrote:
> When calling hugetlb_resv_map_add(), we've guaranteed that the parameter
> 'to' is always larger than 'from', so it never returns a negative value
> from hugetlb_resv_map_add(). Thus remove the redundant VM_BUG_ON().
> 
> Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
> ---
>  mm/hugetlb.c | 1 -
>  1 file changed, 1 deletion(-)

Thanks!  You are correct, we could never trigger that VM_BUG_ON.

Reviewed-by: Mike Kravetz <mike.kravetz@...cle.com>

-- 
Mike Kravetz

> 
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 5922629..166cfa1 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -446,7 +446,6 @@ static long add_reservation_in_range(struct resv_map *resv, long f, long t,
>  		add += hugetlb_resv_map_add(resv, rg, last_accounted_offset,
>  					    t, h, h_cg, regions_needed);
>  
> -	VM_BUG_ON(add < 0);
>  	return add;
>  }
>  
>