Re: [PATCH] NOMMU: Pages allocated to a ramfs inode's pagecache may get wrongly discarded

From: KOSAKI Motohiro
Date: Thu Mar 12 2009 - 22:03:19 EST


Hi

> > Which as Peter points out:
> >
> > The ramfs stuff is rather icky in that it adds the pages to the aging
> > list, marks them dirty, but does not provide a writeout method.
> >
> > This will make the paging code scan over them (continuously) trying to
> > clean them, failing that (lack of writeout method) and putting them back
> > on the list.
> >
> > Not requiring the pages to be added to the LRU would be a really good idea.
> > They are not discardable, be it in MMU or NOMMU mode, except when the inode
> > itself is discarded.
>
> Yep, these pages shouldn't be on the LRU at all. I guess that will
> require some tweaks to core filemap.c code.

IMHO, UNEVICTABLE_LRU already does lru isolation.
only rest prblem is, getting rid of "depends on MMU" line in mm/Kconfig.

Am I missing anything?




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