Re: MM patches against 2.5.31

[Andrew Morton]

Daniel Phillips wrote:
> 
> ...
> So there's no question that the race is lurking in 2.4.  I noticed several
> more paths besides the one above that look suspicious as well.  The bottom
> line is, 2.4 needs a fix along the lines of my suggestion or Christian's,
> something that can actually be proved.
> 
> It's a wonder that this problem manifests so rarely in practice.

I sort-of glanced through the 2.4 paths and it appears that in all of the
places where it could do a page_cache_get/release, that would never happen
because of other parts of the page state.

Like: it can't be in pagecache, so we won't run writepage, and
it can't have buffers, so we won't run try_to_release_page().

Of course, I might have missed a path.  And, well, generally: ugh.