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Date: Mon, 29 Jul 2013 15:05:37 -0400
From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
To: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, Rik van Riel <riel@redhat.com>,
        Mel Gorman <mgorman@suse.de>, Michal Hocko <mhocko@suse.cz>,
        "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        Hugh Dickins <hughd@google.com>,
        Davidlohr Bueso <davidlohr.bueso@hp.com>,
        David Gibson <david@gibson.dropbear.id.au>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Joonsoo Kim <js1304@gmail.com>,
        Wanpeng Li <liwanp@linux.vnet.ibm.com>,
        Hillf Danton <dhillf@gmail.com>
Message-ID: <1375124737-9w10y4c4-mutt-n-horiguchi@ah.jp.nec.com>
In-Reply-To: <1375075929-6119-16-git-send-email-iamjoonsoo.kim@lge.com>
References: <1375075929-6119-1-git-send-email-iamjoonsoo.kim@lge.com>
 <1375075929-6119-16-git-send-email-iamjoonsoo.kim@lge.com>
Subject: Re: [PATCH 15/18] mm, hugetlb: move up anon_vma_prepare()
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On Mon, Jul 29, 2013 at 02:32:06PM +0900, Joonsoo Kim wrote:
> If we fail with a allocated hugepage, it is hard to recover properly.
> One such example is reserve count. We don't have any method to recover
> reserve count. Although, I will introduce a function to recover reserve
> count in following patch, it is better not to allocate a hugepage
> as much as possible. So move up anon_vma_prepare() which can be failed
> in OOM situation.
> 
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>

Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>

> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 683fd38..bb8a45f 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -2536,6 +2536,15 @@ retry_avoidcopy:
>  	/* Drop page_table_lock as buddy allocator may be called */
>  	spin_unlock(&mm->page_table_lock);
>  
> +	/*
> +	 * When the original hugepage is shared one, it does not have
> +	 * anon_vma prepared.
> +	 */
> +	if (unlikely(anon_vma_prepare(vma))) {
> +		ret = VM_FAULT_OOM;
> +		goto out_old_page;
> +	}
> +
>  	use_reserve = vma_has_reserves(h, vma, address);
>  	if (use_reserve == -ENOMEM) {
>  		ret = VM_FAULT_OOM;
> @@ -2590,15 +2599,6 @@ retry_avoidcopy:
>  		goto out_lock;
>  	}
>  
> -	/*
> -	 * When the original hugepage is shared one, it does not have
> -	 * anon_vma prepared.
> -	 */
> -	if (unlikely(anon_vma_prepare(vma))) {
> -		ret = VM_FAULT_OOM;
> -		goto out_new_page;
> -	}
> -
>  	copy_user_huge_page(new_page, old_page, address, vma,
>  			    pages_per_huge_page(h));
>  	__SetPageUptodate(new_page);
> @@ -2625,7 +2625,6 @@ retry_avoidcopy:
>  	spin_unlock(&mm->page_table_lock);
>  	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
>  
> -out_new_page:
>  	page_cache_release(new_page);
>  out_old_page:
>  	page_cache_release(old_page);
> -- 
> 1.7.9.5
> 
> --
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