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Date: Mon, 14 May 2018 15:34:18 +0000
From: Christopher Lameter <cl@linux.com>
Subject: Re: Copy-on-write with vmalloc
In-Reply-To: <alpine.LRH.2.11.1805072224360.31774@mail.ewheeler.net>
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To: Eric Wheeler <linux-mm@lists.ewheeler.net>
Cc: linux-mm@kvack.org

On Mon, 7 May 2018, Eric Wheeler wrote:

> I would like to clone a virtual address space so that the address spaces
> share physical pages until a write happens, at which point it would copy
> to a new physical page.  I've looked around and haven't found any
> documentation. Certainly fork() already does this, but is there already
> simple way to do it with a virtual address space?

The clone() syscall does it (since it is the underlying basis for fork).

The same effect can also be had by using mmap with
MAP_PRIVATE on a shared memory segment.