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

[KOSAKI Motohiro]

(2011/06/10 2:58), Peter Zijlstra wrote:
> On Thu, 2011-06-09 at 14:05 +0200, 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.
> 
> Why can't something like
> http://marc.info/?l=linux-kernel&m=130737669810421 work once you restore
> the rw argument?

Yeah, I agree this is best way. Private RO mappings is not sane and no real
world users.


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/