Re: [Xen-devel] [PATCH XEN v6 30/32] tools/libs/call: linux: avoid forking between mmap and madvise

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Wed, 2015-12-09 at 16:18 +0000, Ian Jackson wrote:
> Ian Campbell writes ("[PATCH XEN v6 30/32] tools/libs/call: linux: avoid
> forking between mmap and madvise"):
> > Use pthread_atfork to prevent the application from forking before the
> > madvisoe(), which would result in CoW mappings getting passed to
> > hypercalls.
> 
> OMG.
> 
> Is it not possible (not effective) to use mlock/madvise in the parent
> ?
> 
> pthread_atfork is a very big hammer to be using in libxc.

I think we decided in our RL conversation the other day that this was
indeed unnecessary and the docs updates (just sent) together with a bug fix
(touch the memory after madvise to un-cow it) would be sufficient for now.

Ian.

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