Re: Change in functionality of futex() system call.

[KOSAKI Motohiro]

(2011/06/09 21:05), Peter Zijlstra wrote:
> On Thu, 2011-06-09 at 20:37 +0900, KOSAKI Motohiro wrote:
>> 1) check the pte of the target address is RW attribute.
>>  2-1) if yes, it has no COW chance. we can safely use gup result.
>>  2-2) if no, we have to fallback slow vma walk. maybe, it's okey.
>>       both RO mappings and COW are rare situation. 
> 
> Not so, clean file pages are RO, even if the vma is writable. We use the
> fault to track dirty state with.

Right you are. Sigh. Please forget my previous mail.

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