Re: [PATCH v3] mm: add mremap flag for preserving the old mapping

From: Daniel Micay
Date: Tue Sep 30 2014 - 22:32:41 EST

On 30/09/14 01:49 PM, Andy Lutomirski wrote:
> I think it might pay to add an explicit vm_op to authorize
> duplication, especially for non-cow mappings. IOW this kind of
> extension seems quite magical for anything that doesn't have the
> normal COW semantics, including for plain old read-only mappings.

This sounds like the best way forwards.

Setting up the op for private, anonymous mappings and having it check
vm_flags & VM_WRITE dynamically seems like it would be enough for the
intended use case in general purpose allocators. It can be extended to
other mapping types later if there's a compelling use case.
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