Re: [PATCH 5/5] Swapless V2: Revise main migration logic

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Mon, 17 Apr 2006 23:58:41 -0700 (PDT)
Christoph Lameter <clameter@sgi.com> wrote:

> Hmmm... Good ideas. I think it could be much simpler like the following 
> patch.
> 
> However, the problem here is how to know that we really took the anon_vma 
> lock and what to do about a page being unmmapped while migrating. This 
> could cause the anon_vma not to be unlocked.
> 
lock dependency here is page_lock(page) -> page's anon_vma->lock.
So, I guess  anon_vma->lock cannot be unlocked by other threads 
if we have page_lock(page).


> I guess we would need to have try_to_unmap return some state information.
What kind of information ?

> I also toyed around with writing an "install_migration_ptes" function 
> which would be called only for anonymous pages and would reduce the 
> changes to try_to_unmap(). However, that also got too complicated.
> 

-Kame


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