linux-kernel - Re: [PATCH] mm/page_reporting: the "page" must not be the list head

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Message-ID: <20200818030343.GB29756@L-31X9LVDL-1304.local>
Date:   Tue, 18 Aug 2020 11:03:43 +0800
From:   Wei Yang <richard.weiyang@...ux.alibaba.com>
To:     David Hildenbrand <david@...hat.com>
Cc:     Wei Yang <richard.weiyang@...ux.alibaba.com>,
        alexander.h.duyck@...ux.intel.com, akpm@...ux-foundation.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/page_reporting: the "page" must not be the list head

On Mon, Aug 17, 2020 at 11:35:29AM +0200, David Hildenbrand wrote:
>On 17.08.20 10:48, Wei Yang wrote:
>> If "page" is the list head, list_for_each_entry_safe() would stop
>> iteration.
>> 
>> Signed-off-by: Wei Yang <richard.weiyang@...ux.alibaba.com>
>> ---
>>  mm/page_reporting.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/mm/page_reporting.c b/mm/page_reporting.c
>> index 3bbd471cfc81..aaaa3605123d 100644
>> --- a/mm/page_reporting.c
>> +++ b/mm/page_reporting.c
>> @@ -178,7 +178,7 @@ page_reporting_cycle(struct page_reporting_dev_info *prdev, struct zone *zone,
>>  		 * the new head of the free list before we release the
>>  		 * zone lock.
>>  		 */
>> -		if (&page->lru != list && !list_is_first(&page->lru, list))
>> +		if (!list_is_first(&page->lru, list))
>>  			list_rotate_to_front(&page->lru, list);
>>  
>>  		/* release lock before waiting on report processing */
>> 
>
>Is this a fix or a cleanup? If it's a fix, can this be reproduced easily
>and what ere the effects?
>

I think this is a cleanup.

I am not sure why you ask this, since the check must be true when the
iteration continues.

>-- 
>Thanks,
>
>David / dhildenb

-- 
Wei Yang
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