Re: [PATCH] NOMMU: Fix MAP_PRIVATE mmap() of objects where the data can be mapped directly

[Andrew Morton <akpm@linux-foundation.org>]

On Thu, 24 Sep 2009 15:13:10 +0100
David Howells <dhowells@redhat.com> wrote:

> Fix MAP_PRIVATE mmap() of files and devices where the data in the backing store
> might be mapped directly.  Use the BDI_CAP_MAP_DIRECT capability flag to govern
> whether or not we should be trying to map a file directly.  This can be used to
> determine whether or not a region has been filled in at the point where we call
> do_mmap_shared() or do_mmap_private().
> 
> The BDI_CAP_MAP_DIRECT capability flag is cleared by validate_mmap_request() if
> there's any reason we can't use it.  It's also cleared in do_mmap_pgoff() if
> f_op->get_unmapped_area() fails.
> 

The patch seems -stable-worthy but I see no cc:stable here?

> Note that this fix does the following commit differently:
> 
> 	commit a190887b58c32d19c2eee007c5eb8faa970a69ba
> 	Author: David Howells <dhowells@redhat.com>
> 	Date:   Sat Sep 5 11:17:07 2009 -0700
> 	nommu: fix error handling in do_mmap_pgoff()

I don't understand what you're saying here.

> Reported-by: Graff Yang <graff.yang@gmail.com>
> Signed-off-by: David Howells <dhowells@redhat.com>
> Cc: Pekka Enberg <penberg@cs.helsinki.fi>
> Cc: Paul Mundt <lethal@linux-sh.org>
> Cc: Mel Gorman <mel@csn.ul.ie>
> Cc: Greg Ungerer <gerg@snapgear.com>