Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752584Ab3HUTVl (ORCPT ); Wed, 21 Aug 2013 15:21:41 -0400 Received: from relay.parallels.com ([195.214.232.42]:44196 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752089Ab3HUTVk (ORCPT ); Wed, 21 Aug 2013 15:21:40 -0400 Message-ID: <5215133D.90005@parallels.com> Date: Wed, 21 Aug 2013 23:21:33 +0400 From: Pavel Emelyanov User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120605 Thunderbird/13.0 MIME-Version: 1.0 To: Andy Lutomirski CC: Cyrill Gorcunov , "H. Peter Anvin" , David Vrabel , Jan Beulich , Andrew Morton , Linus Torvalds , , Boris Ostrovsky , Konrad Rzeszutek Wilk , Ingo Molnar , "linux-kernel@vger.kernel.org" Subject: Re: Regression: x86/mm: new _PTE_SWP_SOFT_DIRTY bit conflicts with existing use References: <5214C524.1050900@citrix.com> <20130821141223.GS18673@moon> <5214F09002000078000ED5C3@nat28.tlf.novell.com> <20130821154238.GV18673@moon> <521500E102000078000ED65C@nat28.tlf.novell.com> <20130821161946.GW18673@moon> <5214F128.1000901@citrix.com> <20130821172547.GY18673@moon> <20130821181733.GC3814@moon> <4fec3e5b-695c-438b-ad6d-55ca50becc4c@email.android.com> <20130821190307.GB18673@moon> In-Reply-To: Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [89.169.95.100] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1410 Lines: 36 On 08/21/2013 11:07 PM, Andy Lutomirski wrote: > On Wed, Aug 21, 2013 at 12:03 PM, Cyrill Gorcunov wrote: >> On Wed, Aug 21, 2013 at 08:50:26PM +0200, H. Peter Anvin wrote: >>> But is there a manifest bug or not? What is the deal with Xen? >>> >> >> I personally don't see bug here because >> >> - this swapped page soft dirty bit is set for non-present entries only, >> never for present ones, just at moment we form swap pte entry >> >> - i don't find any code which would test for this bit directly without >> is_swap_pte call >> >> but the use of paw bit itself is confusing, so I'm working on patch which >> won't use it. Again, if someone knows where exactly access to pse bit when >> pte keeps swap entry may happen (for any purpose other than dirty page >> tracking) please share. > > I doubt that there are cacheability issues here, since the swap type > already overlaps with PWT and PCD. > > What happens if the page being swapped is a THP page? (I have no idea > how, or even if, this works, but presumably PSE is important.) Huge-page is splitted into small ones, then the smaller ones get swapped out. > --Andy > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/