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Mon, 19 Jun 2023 08:35:23 -0400 X-MC-Unique: iZkqP-SwMrCQnSEB2MSuuw-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id A24D52A59570; Mon, 19 Jun 2023 12:35:22 +0000 (UTC) Received: from sirius.home.kraxel.org (unknown [10.39.194.241]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4644740C6F58; Mon, 19 Jun 2023 12:35:22 +0000 (UTC) Received: by sirius.home.kraxel.org (Postfix, from userid 1000) id E201218003AB; Mon, 19 Jun 2023 14:35:15 +0200 (CEST) Date: Mon, 19 Jun 2023 14:35:15 +0200 From: Gerd Hoffmann To: Mike Kravetz Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, dri-devel@lists.freedesktop.org, qemu-devel@nongnu.org, Vivek Kasireddy , Dongwon Kim , Junxiao Chang , kirill.shutemov@linux.intel.com, mhocko@suse.com, jmarchan@redhat.com, muchun.song@linux.dev, James Houghton , David Hildenbrand , Greg Kroah-Hartman , Andrew Morton , stable@vger.kernel.org Subject: Re: [PATCH] udmabuf: revert 'Add support for mapping hugepages (v4)' Message-ID: References: <20230608204927.88711-1-mike.kravetz@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230608204927.88711-1-mike.kravetz@oracle.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 X-Rspamd-Queue-Id: 43F904000B X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: sqop99dqnedacgmkkmafptr8ce4h154c X-HE-Tag: 1687178127-912921 X-HE-Meta: U2FsdGVkX1+qFD0hxlgBxj68oEStpFXNHII4caOdaApBCrOtpKRVyzduf0H/kfEnof4jojpPrtr7EsBgm79boriiVCdYVObFkZeAocCStHlFrrQNZ7t+rmrjbqEl1EOuFRPrxxJCx4buwQjaP1B3w6FZN0T2j6AzJrUv75Yu7yz+wKKY/D+jqT0/qJiOOOVEr+UCAwMUve2itsEBEp2W7tKCKpcfUgWyWKeIdnLv/y4IwaZyLgrGYfcTEStZt+78ZMufC+pOjb5FVHnxX0oXm54YQsZEMVm6ANXtAFV31+a8SlySJP9wSs2550vvT/qHGTE4XUMeI8TjDg77P3+TzP6WKqPoPsfVDJBFw12yD2VtW196W/82mEFahNfHOFl33N/PHxuTwjCeNynvNQlS7UOg6EPwCr7IVH+rbHRWAA4BsMvc1T2y0R5xrxuCqfW+wX9E1yjnYO6WCSRvRtJfOasIAzt+Tv2W9ykHnu4Y6Vp1ycsip69t5OuK6HXdhMTpDlvidws6NKnIndrDzV9+UqTSsy3hutKiJ/n+47wtywLot8G/3EMl7qcHUV+d8ASKRLF2zjU9KeW3/A2YtLa8U+ixT8FMsgPfKsfxg34KsTTeMMD9JaPKnkRkCi8qcFDmqC1JLa4C7Vuv88cZ2T33ttufuWg3MF6tS2EsNN1FuYHLdwoubyMjeHFqqTiCBP5fjkdhb7rDT3oQ1TiOFAjtyP2pycJZO4a8UqaoKnsLlkkQfxg0XO9pLXqKxqwyXqhYYY0QnzSMdRHtFB+85UQiQB7zdL6+PJgaqNht0nuAhua2zgFz1BkTmiXjaNTlr/HB1kEsRiC0Omuw3aLTPSYkyNDm5cXDC+lfKt42r8aer4Frxu0N6Qy719Bh9pJ3UsKZc0ZPdHBT6wi6uo2+1Lf0XpMrRwAsq+r6rORVaege5GxRu5pIQiQ1PGEgtIqi4n7CzRttCqzmytu+hy/KdK/ ZXfhSeyY JEO387BwEu/8w2X37IOdj7+uC2bPw5Cdp4knYgDjFEGx7g7EO0atJEV3/yPhdathBCQkAnrc8MtLxRtVEszkIikGkKg/+MTvDohCXJ4SwQn84110GLUdz5CKTXPUpArRgBcbOSW47JssqLv5XfjOqcnNyl5SJzYfcTBPN4FB5OXpBSrx3valfjNVS3VRGh4MXMEihaalHQhBPrV4kWrcc4Zz7PZZiG4aDeIm922/JBuVMjRbsGe7U6q/ZGPXTkndydlgqh0kj1xCZrBLUl3hhoIJecPDnIMLozDDN 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 Thu, Jun 08, 2023 at 01:49:27PM -0700, Mike Kravetz wrote: > This effectively reverts commit 16c243e99d33 ("udmabuf: Add support > for mapping hugepages (v4)"). Recently, Junxiao Chang found a BUG > with page map counting as described here [1]. This issue pointed out > that the udmabuf driver was making direct use of subpages of hugetlb > pages. This is not a good idea, and no other mm code attempts such use. > In addition to the mapcount issue, this also causes issues with hugetlb > vmemmap optimization and page poisoning. > > For now, remove hugetlb support. > > If udmabuf wants to be used on hugetlb mappings, it should be changed to > only use complete hugetlb pages. This will require different alignment > and size requirements on the UDMABUF_CREATE API. > > [1] https://lore.kernel.org/linux-mm/20230512072036.1027784-1-junxiao.chang@intel.com/ > > Fixes: 16c243e99d33 ("udmabuf: Add support for mapping hugepages (v4)") > Cc: > Signed-off-by: Mike Kravetz Acked-by: Gerd Hoffmann