linux-kernel - Re: [PATCH 4/4] mm/hwpoison: fix the lack of one reference count against poisoned page

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Date:	Mon, 02 Sep 2013 14:34:30 -0400
From:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
To:	Wanpeng Li <liwanp@...ux.vnet.ibm.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Andi Kleen <andi@...stfloor.org>,
	Fengguang Wu <fengguang.wu@...el.com>,
	Tony Luck <tony.luck@...el.com>, gong.chen@...ux.intel.com,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/4] mm/hwpoison: fix the lack of one reference count
 against poisoned page

On Mon, Sep 02, 2013 at 08:33:44PM +0800, Wanpeng Li wrote:
> The lack of one reference count against poisoned page for hwpoison_inject w/o 
> hwpoison_filter enabled result in hwpoison detect -1 users still referenced 
> the page, however, the number should be 0 except the poison handler held one 
> after successfully unmap. This patch fix it by hold one referenced count against 
> poisoned page for hwpoison_inject w/ and w/o hwpoison_filter enabled.
> 
> Before patch:
> 
> [   71.902112] Injecting memory failure at pfn 224706
> [   71.902137] MCE 0x224706: dirty LRU page recovery: Failed
> [   71.902138] MCE 0x224706: dirty LRU page still referenced by -1 users
> 
> After patch:
> 
> [   94.710860] Injecting memory failure at pfn 215b68
> [   94.710885] MCE 0x215b68: dirty LRU page recovery: Recovered
> 
> Signed-off-by: Wanpeng Li <liwanp@...ux.vnet.ibm.com>

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

> ---
>  mm/hwpoison-inject.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/hwpoison-inject.c b/mm/hwpoison-inject.c
> index afc2daa..4c84678 100644
> --- a/mm/hwpoison-inject.c
> +++ b/mm/hwpoison-inject.c
> @@ -20,8 +20,6 @@ static int hwpoison_inject(void *data, u64 val)
>  	if (!capable(CAP_SYS_ADMIN))
>  		return -EPERM;
>  
> -	if (!hwpoison_filter_enable)
> -		goto inject;
>  	if (!pfn_valid(pfn))
>  		return -ENXIO;
>  
> @@ -33,6 +31,9 @@ static int hwpoison_inject(void *data, u64 val)
>  	if (!get_page_unless_zero(hpage))
>  		return 0;
>  
> +	if (!hwpoison_filter_enable)
> +		goto inject;
> +
>  	if (!PageLRU(p) && !PageHuge(p))
>  		shake_page(p, 0);
>  	/*
> -- 
> 1.8.1.2
>
--
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