Re: [PATCH 0/5] mm improvements

Hugh Dickins
2004-02-04T20:54:35Z

On Wed, 4 Feb 2004, Andrew Morton wrote:
> Hugh Dickins <hugh@veritas.com> wrote:
> >
> > Sorry, that BUG_ON is there for very good reason. It's no disgrace
> > that your testing didn't notice the effect of passing a mapped page
> > down to shmem_writepage, but it is a serious breakage of tmpfs.
>
> hm. Can't I force writepage-of-a-mapped-page with msync()?

I hope not, __filemap_fdatawrite still starts off with:

if (mapping->backing_dev_info->memory_backed)
return 0;

Once upon a time you did have vmscan.c calling ->writepages, rather
the effect that Nikita is trying for. It was that writepages which
led me to insert the BUG_ON and give tmpfs a dummy writepages.
Later on you dropped the ->writepages from vmscan.c:
do you remember why? would be useful info for Nikita.

Hugh