Re: [PATCH] mm/hwpoison: fix page refcount of unkown non LRU page

[Wanpeng Li <wanpeng.li@hotmail.com>]

On 8/7/15 3:46 PM, Naoya Horiguchi wrote:
> On Thu, Aug 06, 2015 at 04:09:37PM +0800, Wanpeng Li wrote:
>> After try to drain pages from pagevec/pageset, we try to get reference
>> count of the page again, however, the reference count of the page is 
>> not reduced if the page is still not on LRU list. This patch fix it by 
>> adding the put_page() to drop the page reference which is from 
>> __get_any_page().
>>
>> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> 
> This fix is correct. Thanks you for catching this, Wanpeng!
>
> Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>

Thanks, :)

>
> BTW, I think this patch is worth sending to stable tree. It seems that
> the latest change around this code is given by the following commit:
>
>   commit af8fae7c08862bb85c5cf445bf9b36314b82111f
>   Author: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
>   Date:   Fri Feb 22 16:34:03 2013 -0800
>   
>       mm/memory-failure.c: clean up soft_offline_page()
>
> . I think that this bug existed before this commit, but this patch is
> cleanly applicable only after this patch, so I think tagging
> "Cc: stable@vger.kernel.org # 3.9+" is good.

I will add this in v2.

Regards,
Wanpeng Li

>
> Thanks,
> Naoya Horiguchi
>
>> ---
>>  mm/memory-failure.c |    2 ++
>>  1 files changed, 2 insertions(+), 0 deletions(-)
>>
>> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
>> index c53543d..23163d0 100644
>> --- a/mm/memory-failure.c
>> +++ b/mm/memory-failure.c
>> @@ -1535,6 +1535,8 @@ static int get_any_page(struct page *page, unsigned long pfn, int flags)
>>  		 */
>>  		ret = __get_any_page(page, pfn, 0);
>>  		if (!PageLRU(page)) {
>> +			/* Drop page reference which is from __get_any_page() */
>> +			put_page(page);
>>  			pr_info("soft_offline: %#lx: unknown non LRU page type %lx\n",
>>  				pfn, page->flags);
>>  			return -EIO;
>> -- 
>> 1.7.1

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