Re: [RFC 5/5] truncate: Remove unnecessary page release

[Minchan Kim]

On Mon, Dec 20, 2010 at 11:21 AM, KOSAKI Motohiro
<kosaki.motohiro@xxxxxxxxxxxxxx> wrote:
>> This patch series changes remove_from_page_cache's page ref counting
>> rule. page cache ref count is decreased in remove_from_page_cache.
>> So we don't need call again in caller context.
>>
>> Cc: Nick Piggin <npiggin@xxxxxxx>
>> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
>> Cc: linux-mm@xxxxxxxxx
>> Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx>
>> ---
>>  mm/truncate.c |    1 -
>>  1 files changed, 0 insertions(+), 1 deletions(-)
>>
>> diff --git a/mm/truncate.c b/mm/truncate.c
>> index 9ee5673..8decb93 100644
>> --- a/mm/truncate.c
>> +++ b/mm/truncate.c
>> @@ -114,7 +114,6 @@ truncate_complete_page(struct address_space *mapping, struct page *page)
>>        * calls cleancache_put_page (and note page->mapping is now NULL)
>>        */
>>       cleancache_flush_page(mapping, page);
>> -     page_cache_release(page);       /* pagecache ref */
>>       return 0;
>
> Do we _always_ have stable page reference here? IOW, I can assume

I think so.
Because the page is locked so caller have to hold a ref to unlock it.

> cleancache_flush_page() doesn't cause NULL deref?
>
>
>
>



-- 
Kind regards,
Minchan Kim
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