arm32 binaries work with CONFIG_COMPAT as root but not as user?

[Catalin Marinas]

On Wed, Jan 28, 2015 at 11:42:55AM +0000, Riku Voipio wrote:
> On 28 January 2015 at 13:22, Catalin Marinas <catalin.marinas at arm.com> wrote:
> > On Wed, Jan 28, 2015 at 10:52:21AM +0000, Riku Voipio wrote:
> > What does this say:
> cat /proc/sys/vm/mmap_min_addr
> 65536
> 
> > # cat /proc/sys/vm/mmap_min_addr
> >
> > If it is 64K, it won't run 32-bit apps as non-root.
> 
> echo 32768 > /proc/sys/vm/mmap_min_addr
> 
> and indeed binaries work as expected.
> 
> The ubuntu LTS 3.13 kernel has:
> 
> /boot/config-3.13.0-39-generic:CONFIG_DEFAULT_MMAP_MIN_ADDR=65536
> 
> I need to check how the value ended up wrong on the 3.19-rc3 I tested.

It may be set by some boot script on arm64 Ubuntu (so entirely in user
space).

-- 
Catalin