Re: [PATCH 04/14] mm,migration: Allow the migration of PageSwapCache pages

[Minchan Kim]

Hi, Christoph.

On Fri, Apr 23, 2010 at 12:14 AM, Christoph Lameter <cl@xxxxxxxxx> wrote:
> On Thu, 22 Apr 2010, Minchan Kim wrote:
>
>> For further optimization, we can hold vma->adjust_lock if vma_address
>> returns -EFAULT. But I hope we redesigns it without new locking.
>> But I don't have good idea, now. :(
>
> You could make it atomic through the use of RCU.
>
> Create a new vma entry with the changed parameters and then atomically
> switch to the new vma.
> Problem is that you have some list_heads in there.

That's a good idea if we can do _simply_.
That's because there are many confusion anon_vma and vma handling nowadays.
(http://thread.gmane.org/gmane.linux.kernel/969907)
So I hope we solve the problem without rather complicated rcu locking
if it isn't critical path.

-- 
Kind regards,
Minchan Kim
--
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/