On 21 Feb 2019, at 13:10, Jerome Glisse wrote: > On Fri, Feb 15, 2019 at 02:08:26PM -0800, Zi Yan wrote: >> From: Zi Yan <ziy@xxxxxxxxxx> >> >> In stead of using two migrate_pages(), a single exchange_pages() would >> be sufficient and without allocating new pages. > > So i believe it would be better to arrange the code differently instead > of having one function that special case combination, define function for > each one ie: > exchange_anon_to_share() > exchange_anon_to_anon() > exchange_share_to_share() > > Then you could define function to test if a page is in correct states: > can_exchange_anon_page() // return true if page can be exchange > can_exchange_share_page() > > In fact both of this function can be factor out as common helpers with the > existing migrate code within migrate.c This way we would have one place > only where we need to handle all the special casing, test and exceptions. > > Other than that i could not spot anything obviously wrong but i did not > spent enough time to check everything. Re-architecturing the code like > i propose above would make this a lot easier to review i believe. > Thank you for reviewing the patch. Your suggestions are very helpful. I will restructure the code to help people review it. >> + from_page_count = page_count(from_page); >> + from_map_count = page_mapcount(from_page); >> + to_page_count = page_count(to_page); >> + to_map_count = page_mapcount(to_page); >> + from_flags = from_page->flags; >> + to_flags = to_page->flags; >> + from_mapping = from_page->mapping; >> + to_mapping = to_page->mapping; >> + from_index = from_page->index; >> + to_index = to_page->index; > > Those are not use anywhere ... Will remove them. Thanks. -- Best Regards, Yan Zi
