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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_2 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 8691BC352A1 for ; Wed, 5 Feb 2020 11:37:22 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5914321741 for ; Wed, 5 Feb 2020 11:37:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="cdJvw1/D" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5914321741 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1izIzM-0004Ow-9M; Wed, 05 Feb 2020 11:37:00 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1izIzK-0004Or-QB for xen-devel@lists.xenproject.org; Wed, 05 Feb 2020 11:36:58 +0000 X-Inumbo-ID: cf444a12-480b-11ea-a933-bc764e2007e4 Received: from merlin.infradead.org (unknown [2001:8b0:10b:1231::1]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id cf444a12-480b-11ea-a933-bc764e2007e4; Wed, 05 Feb 2020 11:36:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=Mime-Version:Content-Type:References: In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=s+iA6jFWx4YzHjZA3QBx+qd2WeCyqqWk7eyt9ZEABZA=; b=cdJvw1/DeWElewC8EUMOQbI1di 5broFJU5qIZJvjEAHbB5MWZg9J8wVCNbcG3YkVv43sx3ffaUUZ60AynvmrE2bjiJWskGRrNfVVyEI m3tyZ7kTupSTGZlsuL6fF4QzZ0IEUk/J4FxUR0/xr6Rb+YnMFwvgDJ/mS+83/P0y+Yv2ONucngnf4 Fp7flNwzE1gnqUKwMf1dZMnpcFxi+GK2o+ASAOhUZtmFNXWz8Y1XOAQB+AXkejm9TZQzCXXS7gRhD 5LbXQktWZhvpgHyHMdPJGrhfoqEpZFXSVglU4bu3FcyuPcMA/7UU6szZKeYhAK2+UX4mAxKBwIciI oAgN+G1g==; Received: from 54-240-197-235.amazon.com ([54.240.197.235] helo=u3832b3a9db3152.ant.amazon.com) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1izIz7-0000dx-41; Wed, 05 Feb 2020 11:36:45 +0000 Message-ID: <5fb3a88ee20e7bea8418680f3353982424dd816b.camel@infradead.org> From: David Woodhouse To: Julien Grall , George Dunlap , Jan Beulich , Stewart Hildebrand Date: Wed, 05 Feb 2020 11:36:41 +0000 In-Reply-To: <9d1c6e2b-f155-96f9-deeb-1b1f30c94081@xen.org> References: <20200204151441.10626-1-stewart.hildebrand@dornerworks.com> <89f9cdc5-bd93-7c15-7832-740db273aca6@suse.com> <428eb589-ec3d-1527-02ce-92e2d4367a1a@citrix.com> <81c41a686f6a520936342f04b62d7c27c137f57e.camel@infradead.org> <9d1c6e2b-f155-96f9-deeb-1b1f30c94081@xen.org> X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.1 Mime-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by merlin.infradead.org. See http://www.infradead.org/rpr.html Subject: Re: [Xen-devel] [XEN PATCH v2 1/2] Check zone before merging adjacent blocks in heap X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Stefano Stabellini , Wei Liu , Konrad Rzeszutek Wilk , George Dunlap , Andrew Cooper , Ian Jackson , Jeff Kubascik , xen-devel@lists.xenproject.org Content-Type: multipart/mixed; boundary="===============1021311403999628389==" Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" --===============1021311403999628389== Content-Type: multipart/signed; micalg="sha-256"; protocol="application/x-pkcs7-signature"; boundary="=-6jfLynEfmUlpvNKEnfzW" --=-6jfLynEfmUlpvNKEnfzW Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2020-02-05 at 10:22 +0000, Julien Grall wrote: > However, I don't like the idea of relying on count_info =3D=3D 0. Indeed,= =20 > there are valid case where count_info =3D=3D 0 because it means the page = is=20 > inuse (PCC_state_inuse). >=20 > It might be best if we introduce a new page state that would be the=20 > default value set in the frametable. >=20 > 0 may be an option if we assign a different value to PGC_state_inuse but= =20 > we would need to check if there are places relying on PGC_state_inuse =3D= =3D=20 > 0. I know that assign_pages() does rely on it, I have sent a patch for= =20 > it yesterday. We'd need an extra bit for that. Perhaps we could recognise that PGC_broken is not valid in combination with some of the four PGC_state states, and take that bit back to turn PGC_state into a 3-bit field, which could hold 8 states of which I think we only currently need 7? { zero, inuse, offlining, offlining_broken, offline, offline_broken, free = } > Another option is to use an all 1s value and initialize the frametable= =20 > to all 1s. But I am not entirely sure whether the allocator would be=20 > able to cope with it. We'd zero it in init_heap_pages() for every page, and it would only be still set to all 1s for pages from the boot allocator; as long as all 1s *is* proven to be an invalid state (I think it is); then the same kind of trick checking unlikely(pg->count_info =3D=3D -1) in the free functions as in my earlier straw man, would probably work. I think I prefer zero being the "untouched" state though, rather than all 1s.=20 --=-6jfLynEfmUlpvNKEnfzW Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCECow ggUcMIIEBKADAgECAhEA4rtJSHkq7AnpxKUY8ZlYZjANBgkqhkiG9w0BAQsFADCBlzELMAkGA1UE BhMCR0IxGzAZBgNVBAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2FsZm9yZDEaMBgG A1UEChMRQ09NT0RPIENBIExpbWl0ZWQxPTA7BgNVBAMTNENPTU9ETyBSU0EgQ2xpZW50IEF1dGhl bnRpY2F0aW9uIGFuZCBTZWN1cmUgRW1haWwgQ0EwHhcNMTkwMTAyMDAwMDAwWhcNMjIwMTAxMjM1 OTU5WjAkMSIwIAYJKoZIhvcNAQkBFhNkd213MkBpbmZyYWRlYWQub3JnMIIBIjANBgkqhkiG9w0B AQEFAAOCAQ8AMIIBCgKCAQEAsv3wObLTCbUA7GJqKj9vHGf+Fa+tpkO+ZRVve9EpNsMsfXhvFpb8 RgL8vD+L133wK6csYoDU7zKiAo92FMUWaY1Hy6HqvVr9oevfTV3xhB5rQO1RHJoAfkvhy+wpjo7Q cXuzkOpibq2YurVStHAiGqAOMGMXhcVGqPuGhcVcVzVUjsvEzAV9Po9K2rpZ52FE4rDkpDK1pBK+ 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