Messages in this thread | | | Date | Fri, 27 Mar 2009 13:32:05 +0900 | Subject | Re: Question about PRIVATE_FUTEX | From | Minchan Kim <> |
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Hmm, It seems even shared futex, too.
After calling get_user_pages_fast, get_futex_key calls unlock, put_page, too. Then futex_wait calls get_futex_value_locked. Wouldn't kernel reclaim the page between get_fuex_key and get_futex_value_locked ?
How do we make sure this race condition ?
On Fri, Mar 27, 2009 at 11:12 AM, Minchan Kim <minchan.kim@gmail.com> wrote: > Hi, Peter and Eric. > > I am not expert about futex. > I am sorry if this is dumb question. > > If we use private futex, get_futex_key don't call get_user_pages_fast > which pins page at page table. > Then, get_futex_value_locked calls __cpy_from_user_inatomic with > pagefault_disable. > > Who make sure the user page is mapped at app's page table ? > > -- > Kinds regards, > Minchan Kim >
-- Kinds regards, Minchan Kim
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