Re: [PATCH 3.2 056/185] mm: ensure get_unmapped_area() returnshigher address than mmap_min_addr

From: Luis Henriques
Date: Mon Jan 06 2014 - 07:32:22 EST


On Mon, Jan 06, 2014 at 07:19:10PM +0900, Akira Takeuchi wrote:
> On Fri, 03 Jan 2014 04:26:43 +0000
> Ben Hutchings <ben@xxxxxxxxxxxxxxx> wrote:
>
> > On Sun, 2013-12-29 at 03:08 +0100, Ben Hutchings wrote:
> > > 3.2.54-rc1 review patch. If anyone has any objections, please let me know.
> > >
> > > ------------------
> > >
> > > From: Akira Takeuchi <takeuchi.akr@xxxxxxxxxxxxxxxx>
> > >
> > > commit 2afc745f3e3079ab16c826be4860da2529054dd2 upstream.
> > [...]
> > > [bwh: Backported to 3.2:
> > > As we do not have vm_unmapped_area(), make arch_get_unmapped_area_topdown()
> > > calculate the lower limit for the new area's end address and then compare
> > > addresses with this instead of with len. In the process, fix an off-by-one
> > > error which could result in returning 0 if mm->mmap_base == len.]
> >
> > I'm dropping this as I have no good way to test the backport (it's not
> > used on x86) and I didn't get any confirmation that it's right.
>
> I'm sorry for delayed reply.
>
> Your backport seems right.
> Additionally, I've confirmed the problem is resolved by your backport patch.

Sorry I'm also late for this review.

I guess this means the backport I made for the 3.5 kernel (and released on
3.5.7.26) is incorrect:

http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=commitdiff;h=745545489d25d1b9ecf2d78a8f9a31a362806d2d

Akira, could you please confirm if this is the case so that I revert it in
next release?

Cheers,
--
Luis
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