[RFC PATCH] ARM: mm: lazy cache flushing on non-mapped pages

[Catalin Marinas]

On Wed, May 22, 2013 at 12:55:11PM +0100, Ming Lei wrote:
> Currently flush_dcache_page() thinks pages as non-mapped if
> mapping_mapped(mapping) return false. This approach is very
> coase:
> 	- mmap on part of file may cause all pages backed on
> 	the file being thought as mmaped
> 
> 	- file-backed pages aren't mapped into user space actually
> 	if the memory mmaped on the file isn't accessed

That's the meaning of mapping_mapped(), it doesn't tell whether the page
has a user virtual address.

> This patch also uses page_mapcount() to decide if the page has been
> mapped.

Better use page_mapped() instead.

-- 
Catalin