From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E7420C433E1 for ; Fri, 14 Aug 2020 12:47:36 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9B0AC2087D for ; Fri, 14 Aug 2020 12:47:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=citrix.com header.i=@citrix.com header.b="PJtz4UOp" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9B0AC2087D Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=citrix.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 19BE36B0005; Fri, 14 Aug 2020 08:47:36 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 14C736B0007; Fri, 14 Aug 2020 08:47:36 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 013FA6B0008; Fri, 14 Aug 2020 08:47:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0225.hostedemail.com [216.40.44.225]) by kanga.kvack.org (Postfix) with ESMTP id E055C6B0005 for ; Fri, 14 Aug 2020 08:47:35 -0400 (EDT) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 9C748180AD802 for ; Fri, 14 Aug 2020 12:47:35 +0000 (UTC) X-FDA: 77149150470.08.money34_190131726ffc Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin08.hostedemail.com (Postfix) with ESMTP id 70F801819E785 for ; Fri, 14 Aug 2020 12:47:35 +0000 (UTC) X-HE-Tag: money34_190131726ffc X-Filterd-Recvd-Size: 5033 Received: from esa6.hc3370-68.iphmx.com (esa6.hc3370-68.iphmx.com [216.71.155.175]) by imf18.hostedemail.com (Postfix) with ESMTP for ; Fri, 14 Aug 2020 12:47:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=citrix.com; s=securemail; t=1597409254; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=vqjMOLWnURMtkyVmLKBVLJihqVbQncODXADZyEOQvAk=; b=PJtz4UOpB6clDELaDb6ZI6pYZdOgQbLMZWb/nkw1XwxImClpjYmCfjXE 6R7meuerV1AUV+yh5JrImShIDtGXjalFHi+m4cRsl0aAXPNj/Dmt02nMF J4uayLnDgKXIq0jTr69nHXixg/2CMpAv7pB4XRKDFg/olz7S0TC4Wuuda Y=; Authentication-Results: esa6.hc3370-68.iphmx.com; dkim=none (message not signed) header.i=none IronPort-SDR: w0A6Vy4ueaWrF7WgfuyBrSR1ACS+hknjc95m+9zhN7fc2SAsmovKRsi3m41T/jo7eaFuu78C7Z S5MTDLXuflc0oQ1pEQ7/9xHjpo5CwxYh3w/78O9M19ZBSjqnsDO5hTI/QpYfLCVTsqY3rO+TdA lbC/WWyTBQbMerqZS+yaBvI3Y+TDQgr/7/ffkMR3MsIWS/vtCi8ou01AxoCZ+/N/T1DSOpRv+J GZhylUerYrKxWKmzDSfQJlY510XRbTKxifOc5UaGesqqi1ipL3B/WtYRbgtGC/JNVtACLQ8jDM CR0= X-SBRS: 2.7 X-MesageID: 24855572 X-Ironport-Server: esa6.hc3370-68.iphmx.com X-Remote-IP: 162.221.158.21 X-Policy: $RELAYED X-IronPort-AV: E=Sophos;i="5.76,312,1592884800"; d="scan'208";a="24855572" Date: Fri, 14 Aug 2020 14:47:25 +0200 From: Roger Pau =?utf-8?B?TW9ubsOp?= To: =?utf-8?B?SsO8cmdlbiBHcm/Dnw==?= CC: Christoph Hellwig , , Oleksandr Andrushchenko , David Airlie , Daniel Vetter , Boris Ostrovsky , Stefano Stabellini , Dan Carpenter , Wei Liu , "Yan Yankovskyi" , , , , David Hildenbrand , Michal Hocko , Dan Williams Subject: Re: [PATCH v4 2/2] xen: add helpers to allocate unpopulated memory Message-ID: <20200814124724.GK975@Air-de-Roger> References: <20200811094447.31208-1-roger.pau@citrix.com> <20200811094447.31208-3-roger.pau@citrix.com> <20200813073337.GA16160@infradead.org> <20200813075420.GC975@Air-de-Roger> <20200814072920.GA6126@infradead.org> <20200814095629.GJ975@Air-de-Roger> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: AMSPEX02CAS02.citrite.net (10.69.22.113) To AMSPEX02CL02.citrite.net (10.69.22.126) X-Rspamd-Queue-Id: 70F801819E785 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Aug 14, 2020 at 12:27:32PM +0200, J=C3=BCrgen Gro=C3=9F wrote: > On 14.08.20 11:56, Roger Pau Monn=C3=A9 wrote: > > On Fri, Aug 14, 2020 at 08:29:20AM +0100, Christoph Hellwig wrote: > > > On Thu, Aug 13, 2020 at 09:54:20AM +0200, Roger Pau Monn?? wrote: > > > > On Thu, Aug 13, 2020 at 08:33:37AM +0100, Christoph Hellwig wrote= : > > > > > On Tue, Aug 11, 2020 at 11:44:47AM +0200, Roger Pau Monne wrote= : > > > > > > If enabled (because ZONE_DEVICE is supported) the usage of th= e new > > > > > > functionality untangles Xen balloon and RAM hotplug from the = usage of > > > > > > unpopulated physical memory ranges to map foreign pages, whic= h is the > > > > > > correct thing to do in order to avoid mappings of foreign pag= es depend > > > > > > on memory hotplug. > > > > >=20 > > > > > So please just select ZONE_DEVICE if this is so much better rat= her > > > > > than maintaining two variants. > > > >=20 > > > > We still need to other variant for Arm at least, so both need to = be > > > > maintained anyway, even if we force ZONE_DEVICE on x86. > > >=20 > > > Well, it still really helps reproducability if you stick to one > > > implementation of x86. > > >=20 > > > The alternative would be an explicit config option to opt into it, > > > but just getting a different implementation based on a random > > > kernel option is strange. > >=20 > > Would adding something like the chunk below to the patch be OK? > >=20 > > ---8<--- > > diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig > > index 018020b91baa..5f321a1319e6 100644 > > --- a/drivers/xen/Kconfig > > +++ b/drivers/xen/Kconfig > > @@ -328,7 +328,14 @@ config XEN_FRONT_PGDIR_SHBUF > > tristate > > config XEN_UNPOPULATED_ALLOC > > - bool > > - default y if ZONE_DEVICE && !ARM && !ARM64 > > + bool "Use unpopulated memory ranges for guest mappings" > > + depends on X86 > > + select ZONE_DEVICE > > + default y >=20 > I'd rather use "default XEN_BACKEND" here, as mappings of other guest's > memory is rarely used for non-backend guests. There's also the privcmd and gnt devices which make heavy use of this, so I'm not sure only selecting by default on XEN_BACKEND is the best option. Thanks, Roger.