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=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, 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 80829C433DB for ; Thu, 18 Feb 2021 17:28:08 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id F217864E3E for ; Thu, 18 Feb 2021 17:28:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F217864E3E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=nvidia.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 498916B0006; Thu, 18 Feb 2021 12:28:07 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 44C5A6B006E; Thu, 18 Feb 2021 12:28:07 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 360B76B0070; Thu, 18 Feb 2021 12:28:07 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0206.hostedemail.com [216.40.44.206]) by kanga.kvack.org (Postfix) with ESMTP id 208636B0006 for ; Thu, 18 Feb 2021 12:28:07 -0500 (EST) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id CEF6F18016C91 for ; Thu, 18 Feb 2021 17:28:06 +0000 (UTC) X-FDA: 77832071772.16.part41_0f0185327656 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin16.hostedemail.com (Postfix) with ESMTP id B0356100E6903 for ; Thu, 18 Feb 2021 17:28:06 +0000 (UTC) X-HE-Tag: part41_0f0185327656 X-Filterd-Recvd-Size: 5151 Received: from hqnvemgate24.nvidia.com (hqnvemgate24.nvidia.com [216.228.121.143]) by imf40.hostedemail.com (Postfix) with ESMTP for ; Thu, 18 Feb 2021 17:28:05 +0000 (UTC) Received: from hqmail.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate24.nvidia.com (using TLS: TLSv1.2, AES256-SHA) id ; Thu, 18 Feb 2021 09:28:04 -0800 Received: from [10.2.58.214] (172.20.145.6) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 18 Feb 2021 17:27:59 +0000 From: Zi Yan To: Jason Gunthorpe CC: Matthew Wilcox , Andrew Morton , Mike Kravetz , , , Davidlohr Bueso , "Kirill A . Shutemov" , Andrea Arcangeli , Oscar Salvador , Joao Martins , Subject: Re: [PATCH 1/2] hugetlb: fix update_and_free_page contig page struct assumption Date: Thu, 18 Feb 2021 12:27:58 -0500 X-Mailer: MailMate (1.14r5757) Message-ID: <19612088-4856-4BE9-A731-BB903511F352@nvidia.com> In-Reply-To: <20210218172500.GA4718@ziepe.ca> References: <20210217184926.33567-1-mike.kravetz@oracle.com> <20210217110252.185c7f5cd5a87c3f7b0c0144@linux-foundation.org> <20210218144554.GS2858050@casper.infradead.org> <20210218172500.GA4718@ziepe.ca> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=_MailMate_558FA73B-66C7-4EF3-8577-3AD3907969DF_="; micalg=pgp-sha512; protocol="application/pgp-signature" X-Originating-IP: [172.20.145.6] X-ClientProxiedBy: HQMAIL107.nvidia.com (172.20.187.13) To HQMAIL107.nvidia.com (172.20.187.13) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1613669284; bh=9i8X4BkS+6JMlt9uLwPOgCZEdNoO9x5NgxB0zDcM9zU=; h=From:To:CC:Subject:Date:X-Mailer:Message-ID:In-Reply-To: References:MIME-Version:Content-Type:X-Originating-IP: X-ClientProxiedBy; b=OdmCK3vPYH0iZUNtOEgsO9l1n48Eh99gQAK6DBapsxOS2PCsZNKmsmbicg7JXpMJg eB6zvlgh1jHO0etZ9npkgt5MX2ooUL7+FPl9mBYwD0T1QafkyWzi66oiSfnNqDNUI8 elekzQ80xiRQHhImZHr9Khol9CQV1iuvF2xZ41Zo6muOl5p5lO8gQLznIsrgB8zLTh c/ZUJh3eCH8OvwiIr1IKvkT7uEc1IrEWWVT7Y2oxr9QGZhvP6Gfs3He6zRkcX4KmNj 0E14XYgIQwU4ZUaMaJ4dvI7nmVjrUu6aIP4VPFFXydATrnXdYsO7UTBPKtedsbKlcZ RrUvobJ2HYs/Q== 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: --=_MailMate_558FA73B-66C7-4EF3-8577-3AD3907969DF_= Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On 18 Feb 2021, at 12:25, Jason Gunthorpe wrote: > On Thu, Feb 18, 2021 at 02:45:54PM +0000, Matthew Wilcox wrote: >> On Wed, Feb 17, 2021 at 11:02:52AM -0800, Andrew Morton wrote: >>> On Wed, 17 Feb 2021 10:49:25 -0800 Mike Kravetz wrote: >>>> page structs are not guaranteed to be contiguous for gigantic pages.= The >>> >>> June 2014. That's a long lurk time for a bug. I wonder if some late= r >>> commit revealed it. >> >> I would suggest that gigantic pages have not seen much use. Certainly= >> performance with Intel CPUs on benchmarks that I've been involved with= >> showed lower performance with 1GB pages than with 2MB pages until quit= e >> recently. > > I suggested in another thread that maybe it is time to consider > dropping this "feature" You mean dropping gigantic page support in hugetlb? > > If it has been slightly broken for 7 years it seems a good bet it > isn't actually being used. > > The cost to fix GUP to be compatible with this will hurt normal > GUP performance - and again, that nobody has hit this bug in GUP > further suggests the feature isn't used.. A easy fix might be to make gigantic hugetlb page depends on CONFIG_SPARSEMEM_VMEMMAP, which guarantee all struct pages are contiguous= =2E =E2=80=94 Best Regards, Yan Zi --=_MailMate_558FA73B-66C7-4EF3-8577-3AD3907969DF_= Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQJDBAEBCgAtFiEEh7yFAW3gwjwQ4C9anbJR82th+ooFAmAuo54PHHppeUBudmlk aWEuY29tAAoJEJ2yUfNrYfqK/24QALC+b77e4YBi0DHXfoLMxqHcTGx4G5nnkWoH jke0UQcm48KZ1zsNRUGaHLo7USjCjbwysuQEqfwOciYE5DwH5bHANtzqdu+MLd83 uilXzQzBuSG1ePUnFFKJSoEV8j8JQDaz+7wFpvn0ZlHgi7HSVHgMup+/s+uGxluO 5FiiYcwRuBjY3wApNCTc+UT908QwAGwKdY5RIDM6CWrVkYIsq7nobQA9F8JIeQ38 bSsdz043bLAMdd5Z/XZoNEBOhk++XGuzs+2C1WY0ptC0vgH/dCE0Vvoo8KV92u3O MqKOBx518zeWjgRfvA7NuCn63wqHvhMHwSLiosg5Wa9dJ9Na70U0hX9065WvqU72 294yb7wv6GqidGNl0T97hSlagtmBER1zIYm3nZxsKNL9qCnHljTYvyQv+NFYuZcW Y1tN5INvJwm5qrVju2YEGvC+8lo9RWKUlf8w6mpY55m6Ru/ERRmj6DesPNRr3pSY ajbRJmCxaOZg3f3Vhy8l4E0WpJpWHJOH8LCvQ2EAFwhDiELmYB3ZXIqje2Cvzikn MsD1fCzPKFb4UdcvFLhSt2ry8FboJ/LxLa2nXKWBFsONJe67yEa6TzZdkuBELcMN pFfaOKb64PlNcarGmpTBkxolKP6/W+1oiZFNRnJoPvln+UArPFL0uu0NqK5B03Lc aGUrtfH4 =mXEE -----END PGP SIGNATURE----- --=_MailMate_558FA73B-66C7-4EF3-8577-3AD3907969DF_=--