Re: [RFC] [PATCH] Include LRU in page count

Christian Ehrhardt
2002-09-02T17:18:53Z

On Sat, Aug 31, 2002 at 09:47:29PM +0200, Daniel Phillips wrote:
> > Also there may be lru only pages on the active list, i.e. refill
> > inactive should have this hunk as well:
> >
> > > +#if LRU_PLUS_CACHE==2
> > > + BUG_ON(!page_count(page));
> > > + if (unlikely(page_count(page) == 1)) {
> > > + mmstat(vmscan_free_page);
> > > + BUG_ON(!TestClearPageLRU(page)); // side effect abuse!!
> > > + put_page(page);
> > > + continue;
> > > + }
> > > +#endif
>
> If we have orphans on the active list, we'd probably better just count
> them and figure out what we're doing wrong to put them there in the first
> place. In time they will migrate to the inactive list and get cleaned
> up.

Hm, think of your favourite memory hog being killed with lots of anon
pages on the active list while someone else holds the lru lock.
Won't all these anon pages legally end up orphaned on the active list
(due to the trylock in page_cache_release)?

regards Christian

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