Re: [PATCH 4/8] vmscan: Do not writeback filesystem pages in direct reclaim

Johannes Weiner
2010-07-21T14:40:05Z

On Wed, Jul 21, 2010 at 03:31:19PM +0100, Mel Gorman wrote:
> On Wed, Jul 21, 2010 at 04:28:44PM +0200, Johannes Weiner wrote:
> > On Wed, Jul 21, 2010 at 02:38:57PM +0100, Mel Gorman wrote:
> > > @@ -858,7 +872,7 @@ keep:
> > >
> > > free_page_list(&free_pages);
> > >
> > > - list_splice(&ret_pages, page_list);
> >
> > This will lose all retry pages forever, I think.
> >
>
> Above this is
>
> while (!list_empty(page_list)) {
> ...
> }
>
> page_list should be empty and keep_locked is putting the pages on ret_pages
> already so I think it's ok.

But ret_pages is function-local. Putting them back on the then-empty
page_list is to give them back to the caller, otherwise they are lost
in a dead stack slot.