[dpdk-dev] [PATCH] eal/bsd: don't zero the pages during mmap in contigmem

[Bruce Richardson]

On Mon, May 08, 2017 at 08:09:16AM +0000, Tiwei Bie wrote:
> Don't zero the pages during mmap in contigmem. Instead, zero the
> pages after mmap in primary process. Otherwise, the multi-process
> support will be broken, as the pages will be zeroed when secondary
> processes map the memory.
> 
> Fixes: 82f931805506 ("contigmem: zero all pages during mmap")
> Cc: stable at dpdk.org
> 
> Signed-off-by: Tiwei Bie <tiwei.bie at intel.com>
> ---
I agree there is a problem here, but I'm not sure about the solution to
it. I still think that the kernel should zero the pages before they get
given to userspace. Is there any way to keep that working e.g

* have them zeroed on mmap only when they are not already mmaped into
  another process?
* have them zeroed on init, and again on unmap by the last process to
  have them mapped?

/Bruce