Re: Nick's core remove PageReserved broke vmware...

[Michael S. Tsirkin]

Quoting Gleb Natapov <gleb@xxxxxxxxxxxxx>:
> Subject: Re: Nick's core remove PageReserved broke vmware...
> 
> On Mon, Nov 14, 2005 at 02:25:35PM +0200, Michael S. Tsirkin wrote:
> > Quoting Hugh Dickins <hugh@xxxxxxxxxxx>:
> > > Subject: Re: Nick's core remove PageReserved broke vmware...
> > > 
> > > On Tue, 8 Nov 2005, Michael S. Tsirkin wrote:
> > > > 
> > > > Hugh, did you have something like the following in mind
> > > > (this is only boot-tested and only on x86-64)?
> > > 
> > > Yes, that looks pretty good to me, a few comments below.
> > > Only another twenty or so architectures to go ;)
> > 
> > There's one thing that I have thought about: what happens
> > if I set DONTFORK on a page which already has COW set
> > (e.g. after fork)?
> > 
> > It seems that the right thing would be to force a page copy -
> > otherwise the page can get copied on write.
>
> I thought about it. It should not happen for OpenIB since get_user_pages
> will break COW for us and I don't think we should complicate DONTFORK
> implementation by doing break during madvise().

Hmm, I assumed we call madvise before driver does get_user_pages,
otherwise an application could fork in between.
Should we worry about this?

-- 
MST
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