linux-kernel - Re: [PATCH] mm:Make the function zap_huge

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Message-ID: <20150702072621.GB12547@dhcp22.suse.cz>
Date:	Thu, 2 Jul 2015 09:26:21 +0200
From:	Michal Hocko <mhocko@...e.cz>
To:	Nicholas Krause <xerofoify@...il.com>
Cc:	akpm@...ux-foundation.org, mgorman@...e.de,
	n-horiguchi@...jp.nec.com, sasha.levin@...cle.com,
	Yalin.Wang@...ymobile.com, jmarchan@...hat.com,
	kirill@...temov.name, rientjes@...gle.com, vbabka@...e.cz,
	aneesh.kumar@...ux.vnet.ibm.com, ebru.akagunduz@...il.com,
	hannes@...xchg.org, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [PATCH] mm:Make the function zap_huge_pmd bool

On Wed 01-07-15 14:27:57, Nicholas Krause wrote:
> This makes the function zap_huge_pmd have a return type of bool
> now due to this particular function always returning one or zero
> as its return value.

How does this help anything? IMO this just generates a pointless churn
in the code without a good reason.

> Signed-off-by: Nicholas Krause <xerofoify@...il.com>
> ---
>  include/linux/huge_mm.h | 2 +-
>  mm/huge_memory.c        | 6 +++---
>  2 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> index f10b20f..e83174e 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -19,7 +19,7 @@ extern struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
>  					  unsigned long addr,
>  					  pmd_t *pmd,
>  					  unsigned int flags);
> -extern int zap_huge_pmd(struct mmu_gather *tlb,
> +extern bool zap_huge_pmd(struct mmu_gather *tlb,
>  			struct vm_area_struct *vma,
>  			pmd_t *pmd, unsigned long addr);
>  extern int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index c107094..32b1993 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1384,11 +1384,11 @@ out:
>  	return 0;
>  }
>  
> -int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
> +bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
>  		 pmd_t *pmd, unsigned long addr)
>  {
>  	spinlock_t *ptl;
> -	int ret = 0;
> +	int ret = false;
>  
>  	if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
>  		struct page *page;
> @@ -1419,7 +1419,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
>  			tlb_remove_page(tlb, page);
>  		}
>  		pte_free(tlb->mm, pgtable);
> -		ret = 1;
> +		ret = true;
>  	}
>  	return ret;
>  }
> -- 
> 2.1.4
> 

-- 
Michal Hocko
SUSE Labs
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