linux-kernel - Re: [PATCH] mm/rmap.c: remove set but not used variable 'cstart'

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Message-ID: <10d2821c-cc56-961b-8f43-ae9097ed0621@oracle.com>
Date:   Wed, 24 Jul 2019 11:24:10 -0700
From:   Mike Kravetz <mike.kravetz@...cle.com>
To:     YueHaibing <yuehaibing@...wei.com>, akpm@...ux-foundation.org,
        jglisse@...hat.com, kirill.shutemov@...ux.intel.com,
        rcampbell@...dia.com, ktkhai@...tuozzo.com,
        colin.king@...onical.com
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH] mm/rmap.c: remove set but not used variable 'cstart'

On 7/24/19 7:14 AM, YueHaibing wrote:
> Fixes gcc '-Wunused-but-set-variable' warning:
> 
> mm/rmap.c: In function page_mkclean_one:
> mm/rmap.c:906:17: warning: variable cstart set but not used [-Wunused-but-set-variable]
> 
> It is not used any more since
> commit cdb07bdea28e ("mm/rmap.c: remove redundant variable cend")

It appears Commit 0f10851ea475 ("mm/mmu_notifier: avoid double notification
when it is useless") is what removed the use of cstart and cend.  And, they
should have been removed then.

> Reported-by: Hulk Robot <hulkci@...wei.com>
> Signed-off-by: YueHaibing <yuehaibing@...wei.com>

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

> ---
>  mm/rmap.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/mm/rmap.c b/mm/rmap.c
> index ec1af8b..40e4def 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -903,10 +903,9 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
>  	mmu_notifier_invalidate_range_start(&range);
>  
>  	while (page_vma_mapped_walk(&pvmw)) {
> -		unsigned long cstart;
>  		int ret = 0;
>  
> -		cstart = address = pvmw.address;
> +		address = pvmw.address;
>  		if (pvmw.pte) {
>  			pte_t entry;
>  			pte_t *pte = pvmw.pte;
> @@ -933,7 +932,6 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
>  			entry = pmd_wrprotect(entry);
>  			entry = pmd_mkclean(entry);
>  			set_pmd_at(vma->vm_mm, address, pmd, entry);
> -			cstart &= PMD_MASK;
>  			ret = 1;
>  #else
>  			/* unexpected pmd-mapped page? */
>