linux-kernel - Re: [PATCH] mm: rmap: use VM_BUG_ON() in __page_check_anon

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Message-ID: <20191106082848.eukf2jnjqxlvxgnx@box>
Date:   Wed, 6 Nov 2019 11:28:48 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Yang Shi <yang.shi@...ux.alibaba.com>
Cc:     akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: rmap: use VM_BUG_ON() in __page_check_anon_rmap()

On Wed, Nov 06, 2019 at 01:03:36AM +0800, Yang Shi wrote:
> The __page_check_anon_rmap() just calls two BUG_ON()s protected by
> CONFIG_DEBUG_VM, the #ifdef could be eliminated by using VM_BUG_ON().
> 
> Signed-off-by: Yang Shi <yang.shi@...ux.alibaba.com>
> ---
>  mm/rmap.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/rmap.c b/mm/rmap.c
> index d17cbf3..39178eb 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1055,7 +1055,6 @@ static void __page_set_anon_rmap(struct page *page,
>  static void __page_check_anon_rmap(struct page *page,
>  	struct vm_area_struct *vma, unsigned long address)
>  {
> -#ifdef CONFIG_DEBUG_VM
>  	/*
>  	 * The page's anon-rmap details (mapping and index) are guaranteed to
>  	 * be set up correctly at this point.
> @@ -1068,9 +1067,8 @@ static void __page_check_anon_rmap(struct page *page,
>  	 * are initially only visible via the pagetables, and the pte is locked
>  	 * over the call to page_add_new_anon_rmap.
>  	 */
> -	BUG_ON(page_anon_vma(page)->root != vma->anon_vma->root);
> -	BUG_ON(page_to_pgoff(page) != linear_page_index(vma, address));
> -#endif
> +	VM_BUG_ON(page_anon_vma(page)->root != vma->anon_vma->root);
> +	VM_BUG_ON(page_to_pgoff(page) != linear_page_index(vma, address));

Why not VM_BUG_ON_PAGE()?

-- 
 Kirill A. Shutemov