Re: 2.4.10 VM: what avoids from having lots of unwriteable inactive pages

From: Marcelo Tosatti (marcelo@conectiva.com.br)
Date: Mon Sep 24 2001 - 17:39:38 EST


On Mon, 24 Sep 2001, Linus Torvalds wrote:

>
> On Mon, 24 Sep 2001, Marcelo Tosatti wrote:
> >
> > What avoids us from having a lot of unfreeable (eg mapped by ptes) pages
> > on the inactive list ?
>
> Nothing.
>
> If we can't shrink them, we'll fall out and do vmscanning.
>
> Which is exactly what we want to do - it automatically acts as a "uhhuh,
> we've got to do something now" thing.

Think about a case where the inactive list if _full_ of mapped pages.
(which can easily happen, because one fault (do_swap_page) will _not_ move
the page to the active list directly --- it has to be accessed (Referenced
bit) twice (mark_page_accessed)).

We _think_ we don't have a shortage, so we won't call refill_inactive().

We keep calling swap_out(), which will not deactivate pages which _can_ be
written out, until we deactivate the pte's from the pages which are on the
inactive list.

Nothing prevents that, right ?

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



This archive was generated by hypermail 2b29 : Sun Sep 30 2001 - 21:00:27 EST