Re: [RFC PATCH] asynchronous page fault.

[KAMEZAWA Hiroyuki]

Peter Zijlstra さんは書きました：
> On Mon, 2009-12-28 at 09:36 +0900, KAMEZAWA Hiroyuki wrote:
>>
>> > The idea is to let the RCU lock span whatever length you need the vma
>> > for, the easy way is to simply use PREEMPT_RCU=y for now,
>>
>> I tried to remove his kind of reference count trick but I can't do that
>> without synchronize_rcu() somewhere in unmap code. I don't like that and
>> use this refcnt.
>
> Why, because otherwise we can access page tables for an already unmapped
> vma? Yeah that is the interesting bit ;-)
>
Without that
  vma->a_ops->fault()
and
  vma->a_ops->unmap()
can be called at the same time. and vma->vm_file can be dropped while
vma->a_ops->fault() is called. etc...
Ah, I may miss something. I'll consider in the next year.

Thanks,
-Kame

--
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/