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d=linuxfoundation.org; s=korg; t=1686290959; bh=VymAURH6DqwhMHojBPt5ZuPQYK69zpD8+HmhzERJHQs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=BUcm9vafTjmhcgggePjJmaz/CH0W+mbeHr5qrrQwiB0h1f0JVSlBxyQKzOgMopEnY lFRs6FwN6lXiIizorV33KI6IMNKLqQPxpXoK4tRUII5GGb3Z08TYo2zB8FwXnZmiP8 Hwt8ucnJj7jNCiplSapmsMgpbeFiRHshdQZliN6g= Date: Fri, 9 Jun 2023 08:09:17 +0200 From: Greg Kroah-Hartman To: Mike Kravetz Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, dri-devel@lists.freedesktop.org, qemu-devel@nongnu.org, Gerd Hoffmann , 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 , Andrew Morton , stable@vger.kernel.org Subject: Re: [PATCH] udmabuf: revert 'Add support for mapping hugepages (v4)' Message-ID: <2023060908-pretender-boastful-cbb9@gregkh> 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-Rspamd-Queue-Id: 9AE874000C X-Rspam-User: X-Stat-Signature: s5sw3koqaes3tht99g637zqjgwpgstyw X-Rspamd-Server: rspam01 X-HE-Tag: 1686290961-515071 X-HE-Meta: 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 bDIos70Q GDzHjcFT1JWSQjnn4xmB2o7Oya8ZEgoD7J490icq0W7GJjDr9sPTfP325/F8jb/iSrM9u39d9DMDnlY4EDHMY73aP9c0yqswFFBSzYHJGoitUVJyDHLxpAgqR+MeG7aZemUqejJzW2Tk9OEZ2+oDQ2FCbHLfgCtU6oxfsbA9HkkLBgSlB6NevxNfWwM90ICmY7/YDeG3bAnDbFaDC9Npn9a4ToHcq75gEROsC03GjfwBSG1lTTj/tnsVCwwrGgSbJAnX/nfLyBZmDcg15xuRlfNhZNisjR1Lp0I69qs58feXtsMKM/BPKYnGy54jR5uoxF4wmVKY7CtsquPfivOCt0KkTgiprXQv56nFCf+8F6u55cW4mL6khFH9YJ2FAsUVX/46p4G7TXdcKBWhngHwXA4Qz9OgVXofwjCdxnjKETnEDDUAVOimNHrXpQBwju1sNjKubkCY2SEixzg8vUi1Xtvd8xfibxnRZomh/ 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: Greg Kroah-Hartman