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SubjectRe: [openib-general] Re: madvise MADV_DONTFORK/MADV_DOFORK
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    Linus> Why?

Linus> That VM_DONTCOPY _is_ DONTFORK.

Linus> Don't add a new useless DONTFORK that doesn't have any
Linus> value.

VM_DONTCOPY is hardly used in the kernel, so the semantics aren't very
precisely defined. But the idea is that a driver setting VM_DONTCOPY
probably has a good reason for doing it, and we don't want userspace
to be able to erase that flag through madvise().

As Hugh said in his suggestion for a better changelog entry:

> Explain that MADV_DONTFORK should be reversible, hence
> MADV_DOFORK; but should not be reversible on areas a driver has
> so marked, hence VM_DONTFORK distinct from VM_DONTCOPY.

Perhaps we don't care for now, and we should wait and add
VM_KERNEL_DONTCOPY later if we really need it. I honestly don't know.

- Roland
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