[Question] Why PageReadahead is not migrated by migration code?

[Yang Shi]

Hi folks,


Recently we saw some PageReadahead related bugs, so I did a quick check 
about the use of PageReadahead. I just found the state is *not* migrated 
by migrate_page_states().


Since migrate_page() won't migrate writeback page, so if PageReadahead 
is set it should just mean PG_readahead rather than PG_reclaim. So, I 
didn't think of why it is not migrated.


I dig into the history a little bit, but the change in migration code is 
too overwhelming. But, it looks PG_readahead was added after migration 
was introduced. Is it just a simple omission?


Thanks,

Yang