Re: [RFC PATCH] mm: fix mlock incorrent event account

[zhong jiang <zhongjiang@huawei.com>]

On 2017/5/25 16:13, Michal Hocko wrote:
> On Thu 25-05-17 15:59:39, zhongjiang wrote:
>> From: zhong jiang <zhongjiang@huawei.com>
>>
>> when clear_page_mlock call, we had finish the page isolate successfully,
>> but it fails to increase the UNEVICTABLE_PGMUNLOCKED account.
>>
>> The patch add the event account when successful page isolation.
> Could you describe _what_ is the problem, how it can be _triggered_
> and _how_ serious it is. Is it something that can be triggered from
> userspace? The mlock code is really tricky and it is far from trivial
> to see whether this is obviously right or a wrong assumption on your
> side. Before people go and spend time reviewing it is fair to introduce
> them to the problem.
>
> I believe this is not the first time I am giving you this feedback
> so I would _really_ appreciated if you tried harder with the changelog.
> It is much simpler to write a patch than review it in many cases.
 HI, MIchal
 
  I am sorry for that. I will keep in mind. 

  As for the above issue. I get the conclusin after reviewing the code.
  I will further prove wheher the issue is exist or not.

  Thanks
  zhongjiang
>> Signed-off-by: zhong jiang <zhongjiang@huawei.com>
>> ---
>>  mm/mlock.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/mm/mlock.c b/mm/mlock.c
>> index c483c5c..941930b 100644
>> --- a/mm/mlock.c
>> +++ b/mm/mlock.c
>> @@ -64,6 +64,7 @@ void clear_page_mlock(struct page *page)
>>  			    -hpage_nr_pages(page));
>>  	count_vm_event(UNEVICTABLE_PGCLEARED);
>>  	if (!isolate_lru_page(page)) {
>> +		count_vm_event(UNEVICTABLE_PGMUNLOCKED);
>>  		putback_lru_page(page);
>>  	} else {
>>  		/*
>> -- 
>> 1.8.3.1


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