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

From: Andrew Morton
Date: Thu Sep 24 2009 - 18:11:04 EST


On Thu, 24 Sep 2009 15:13:10 +0100
David Howells <dhowells@xxxxxxxxxx> 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@xxxxxxxxxx>
> 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@xxxxxxxxx>
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> Cc: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
> Cc: Paul Mundt <lethal@xxxxxxxxxxxx>
> Cc: Mel Gorman <mel@xxxxxxxxx>
> Cc: Greg Ungerer <gerg@xxxxxxxxxxxx>

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