Re: How to reclaim inode pages on demand

[Mel Gorman <mel@csn.ul.ie>]

On Mon, 8 Aug 2005, Andrew Morton wrote:

> Mel Gorman <mel@csn.ul.ie> wrote:
> >
> > Hi,
> >
> > I am working on a direct reclaim strategy to free up large blocks of
> > contiguous pages. The part I have is working fine, but I am finding a
> > hundreds of pages that are being used for inodes that I need to reclaim. I
> > tried purging the inode lists using a variation of prune_icache() but it
> > is not working out.
> >
> > Given a struct page, that one knows is an inode, can anyone suggest the
> > best way to find the inode using it and free it?
>
> Simple answer: invalidate_mapping_pages(page->mapping, start, end).
>

The majority of pages I am seeing no longer have page->mapping set. Does
this mean they are in the process of being cleared up?

> Problem: races.  If you pick a random page up off the LRU and start playing
> with its mapping, what stops that mapping from getting freed under your
> feet?
>

Nothing at all, which explains why I occasionally got oops when I was
trying to free pages with the mapping set. I am going to follow your
suggestions and see how I get on.

If it is still not working out, I will try reclaiming when the workload is
something other than a large number of kernel compiles to see if I am on
the right track at all.

Thanks a lot