On Tue, 5 Feb 2008, Andrea Arcangeli wrote: > On Mon, Feb 04, 2008 at 11:09:01AM -0800, Christoph Lameter wrote: > > On Sun, 3 Feb 2008, Andrea Arcangeli wrote: > > > > > > Right but that pin requires taking a refcount which we cannot do. > > > > > > GRU can use my patch without the pin. XPMEM obviously can't use my > > > patch as my invalidate_page[s] are under the PT lock (a feature to fit > > > GRU/KVM in the simplest way), this is why an incremental patch adding > > > invalidate_range_start/end would be required to support XPMEM too. > > > > Doesnt the kernel in some situations release the page before releasing the > > pte lock? Then there will be an external pte pointing to a page that may > > now have a different use. Its really bad if that pte does allow writes. > > Sure the kernel does that most of the time, which is for example why I > had to use invalidate_page instead of invalidate_pages inside > zap_pte_range. Zero problems with that (this is also the exact reason > why I mentioned the tlb flushing code would need changes to convert > some page in pages).
Zero problems only if you find having a single callout for every page acceptable. So the invalidate_range in your patch is only working sometimes. And even if it works then it has to be used on 2M range. Seems to be a bit fragile and needlessly complex. "conversion of some page in pages"? A proposal to defer the freeing of the pages until after the pte_unlock? ------------------------------------------------------------------------- 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
