Re: Does get_user_pages_fast lock the user pages in memory in my case?

[Minchan Kim <minchan.kim@gmail.com>]

On Wed, Apr 22, 2009 at 3:08 PM, Huang Shijie <shijie8@gmail.com> wrote:
>
>>> I read the kernel code again. In my case ,the kernel will pin the pages
>>> in memory.
>>> I missed function is_page_cache_freeable() in the pageout().
>>>
>>> In my case, is_page_cache_freeable()will return false ,for
>>> page_count(page) is 3 now:
>>> <1> one is from alloc_page_* in page fault.
>>> <2> one is from get_usr_pages()
>>> <3> one is from add_to_swap() in shrink_page_list()
>>>
>>
>> One more, try_to_unmap will call page_cache_release. So, count is 2.
>>
>
> I found I missed something.When code reachs is_page_cache_freeable().
> page_count(page) is 3:
>
> <1> alloc_page_* in page fault . [page count is 1]
> <2> get_usr_pages().             [page count is 2]
> <3> isolate_pages_global()       [page count is 3]
> <4> add_to_swap()                [page count is 4]
> <5> try_to_unmap()               [page count is 3]
>
Yes. It seems you're right.
I missed isolate. ;-;
Thanks for fixing me.

> so it not a bug, just a vicious circle.
>
> Do i miss something?
>
>
>



-- 
Kinds regards,
Minchan Kim

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