Re: page_launder() bug

Linus Torvalds
2001-05-13T19:34:42Z

On Sun, 13 May 2001, Rik van Riel wrote:
>
> Why the hell would we want this ?

You've missed about half the discussion, it seems..

> If the page is referenced, it should be moved back to the
> active list and should never be a candidate for writeout.

Wrong.

There are
(a) dead swap pages, where it doesn't matter one _whit_ whether it is
referenced or not, because we know with 100% certainty that nobody
will ever reference it again. This _may_ be true in other cases too,
but we know it is true for swap pages that have lost all references.
(b) filesystems and memory allocators that might want to get feedback on
the fact that we're even _looking_ at their pages, and that we're
aging them down. They might easily use these things for starting
background activity like deciding to close the logs..

The high-level VM layer simply doesn't have that kind of information.

Linus