On Fri, 1 Feb 2008, Robin Holt wrote: > On Fri, Feb 01, 2008 at 03:19:32PM -0800, Christoph Lameter wrote: > > On Fri, 1 Feb 2008, Robin Holt wrote: > > > > > We are getting this callout when we transition the pte from a read-only > > > to read-write. Jack and I can not see a reason we would need that > > > callout. It is causing problems for xpmem in that a write fault goes > > > to get_user_pages which gets back to do_wp_page that does the callout. > > > > Right. You placed it there in the first place. So we can drop the code > > from do_wp_page? > > No, we need a callout when we are becoming more restrictive, but not > when becoming more permissive. I would have to guess that is the case > for any of these callouts. It is for both GRU and XPMEM. I would > expect the same is true for KVM, but would like a ruling from Andrea on > that.
do_wp_page is entered when the pte shows that the page is not writeable and it makes the page writable in some situations. Then we do not invalidate the remote reference. However, when we do COW then a *new* page is put in place of the existing readonly page. At that point we need to remove the remote pte that is readonly. Then we install a new pte pointing to a *different* page that is writable. Are you saying that you get the callback when transitioning from a read only to a read write pte on the *same* page? ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
