[7ca0fdf] Disable munmap() if it causes VM map holes

[Mike Hommey]

On Mon, Apr 16, 2012 at 12:07:58PM -0700, Jason Evans wrote:
> On Apr 16, 2012, at 8:08 AM, Mike Hommey wrote:
> > I noticed something "interesting" with the test for VM map holes: If
> > I compile it manually, it fails:
> > 
> >  Hoped for 0x7f835133d000, got 0x7f8350b3d000
> >  0x7f835173d000..0x7f835133d000..0x7f8350f3d000..0x7f835073d000..0x7f8350b3d000
> > 
> > Apparently, this happens when *not* linking libm to the testcase. It
> > also does happen when linking libm and some other library (tried
> > pthread and stdc++).
> 
> What OS is this on?  The test should fail on Linux, but not OS X or
> FreeBSD.  Linux has a VM map management quirk (on at least x86) that
> causes accumulation of VM map holes under normal operation.

Linux x64. Kernel 3.2.

So, you are saying that this error is the "expected" behaviour, except I
actually don't get it under "normal" conditions (those of configure.ac)

Mike