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

From: Hugh Dickins
Date: Thu Nov 10 2005 - 08:22:27 EST


On Thu, 10 Nov 2005, Michael S. Tsirkin wrote:
> Quoting Gleb Natapov <gleb@xxxxxxxxxxxxx>:
> > On Thu, Nov 10, 2005 at 02:48:53PM +0200, Michael S. Tsirkin wrote:
> > > > Also perhapse we should skip VM_SHARED VMAs?
> > >
> > > Why?
> > >
> > They will work correctly across fork().
>
> So why would I call madvise on such a VMA?

To avoid the overhead of forking it e.g. if it's a large nonlinear vma,
a lot of time may be wasted on copying its ptes for fork. That's one
of the reasons I came to like your DONTCOPY.

So, it may not be useful for your particular RDMA issue, but I see no
reason to exclude VM_SHARED vmas from the madvise, and good reason to
include them.

Hugh
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