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Date: Mon, 8 May 2017 17:13:34 +0800
From: Tiwei Bie <tiwei.bie@intel.com>
To: Bruce Richardson <bruce.richardson@intel.com>
Cc: dev@dpdk.org, stable@dpdk.org
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Subject: Re: [dpdk-dev] [PATCH] eal/bsd: don't zero the pages during mmap in
contigmem
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On Mon, May 08, 2017 at 09:53:57AM +0100, Bruce Richardson wrote:
> 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@dpdk.org
> >
> > Signed-off-by: Tiwei Bie <tiwei.bie@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?
>
I think it's the simplest way to fix it in userspace, so I just did it.
I'd like to fix it in kernel if you also prefer this.
Best regards,
Tiwei Bie