linux-kernel - Re: [PATCH v2 10/20] mm, hugetlb: remove resv_map

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Date:	Wed, 21 Aug 2013 16:19:20 +0530
From:	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To:	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Rik van Riel <riel@...hat.com>, Mel Gorman <mgorman@...e.de>,
	Michal Hocko <mhocko@...e.cz>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Hugh Dickins <hughd@...gle.com>,
	Davidlohr Bueso <davidlohr.bueso@...com>,
	David Gibson <david@...son.dropbear.id.au>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Joonsoo Kim <js1304@...il.com>,
	Wanpeng Li <liwanp@...ux.vnet.ibm.com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Hillf Danton <dhillf@...il.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH v2 10/20] mm, hugetlb: remove resv_map_put()

Joonsoo Kim <iamjoonsoo.kim@....com> writes:

> In following patch, I change vma_resv_map() to return resv_map
> for all case. This patch prepares it by removing resv_map_put() which
> doesn't works properly with following change, because it works only for
> HPAGE_RESV_OWNER's resv_map, not for all resv_maps.
>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 73034dd..869c3e0 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -2212,15 +2212,6 @@ static void hugetlb_vm_op_open(struct vm_area_struct *vma)
>  		kref_get(&resv->refs);
>  }
>
> -static void resv_map_put(struct vm_area_struct *vma)
> -{
> -	struct resv_map *resv = vma_resv_map(vma);
> -
> -	if (!resv)
> -		return;
> -	kref_put(&resv->refs, resv_map_release);
> -}

Why not have seperate functions to return vma_resv_map for
HPAGE_RESV_OWNER and one for put ? That way we could have something like

resv_map_hpage_resv_owner_get()
resv_map_hpge_resv_put() 

Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>

> -
>  static void hugetlb_vm_op_close(struct vm_area_struct *vma)
>  {
>  	struct hstate *h = hstate_vma(vma);
> @@ -2237,7 +2228,7 @@ static void hugetlb_vm_op_close(struct vm_area_struct *vma)
>  		reserve = (end - start) -
>  			region_count(resv, start, end);
>
> -		resv_map_put(vma);
> +		kref_put(&resv->refs, resv_map_release);
>
>  		if (reserve) {
>  			hugetlb_acct_memory(h, -reserve);
> @@ -3164,8 +3155,8 @@ int hugetlb_reserve_pages(struct inode *inode,
>  		region_add(resv_map, from, to);
>  	return 0;
>  out_err:
> -	if (vma)
> -		resv_map_put(vma);
> +	if (vma && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
> +		kref_put(&resv_map->refs, resv_map_release);

for this

    if (alloc)
           resv_map_hpage_resv_put();

>  	return ret;
>  }
>
> -- 
> 1.7.9.5

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