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bh=K7QsNx354p5UJb+W0jt0jJmIo1DtPxXeGq1FHy48xWw=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=KTNvxPinFizEuJn1y1ca+OL7HSvTz45fSL1nS4DIvD+mRfKBSBF+XQsXofn0uAWLw Cm9GZS4khbbCdQlp00yyEJPPiS6HTZ5LXu/afx0eqEv2zq4yCcTz2jcQkzb3crBfLf mwoI4754n1XsqP8Oqd8DCAaT0ZMyvzV3fKt5xAJg= Date: Wed, 7 Jun 2023 14:00:01 -0700 From: Andrew Morton To: Mike Kravetz Cc: Gerd Hoffmann , Junxiao Chang , kirill.shutemov@linux.intel.com, mhocko@suse.com, jmarchan@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, muchun.song@linux.dev, Vivek Kasireddy , Dongwon Kim , James Houghton , dri-devel@lists.freedesktop.org, Greg Kroah-Hartman Subject: Re: [PATCH] mm: fix hugetlb page unmap count balance issue Message-Id: <20230607140001.6685b0a058511f125a005da4@linux-foundation.org> In-Reply-To: <20230607205310.GA4122@monkey> References: <20230512072036.1027784-1-junxiao.chang@intel.com> <20230512232947.GA3927@monkey> <20230515170259.GA3848@monkey> <20230516223440.GA30624@monkey> <20230607120312.6da5cea7677ec1a3da35b92c@linux-foundation.org> <20230607205310.GA4122@monkey> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 874A440021 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: gn5sr98r81pab441o47w75ctx933resq X-HE-Tag: 1686171604-461084 X-HE-Meta: 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 8O+qp1za qB8ATWTebSD8n3HQQmXI8BAdpAIYFMmNmbj4eBbx0kj5O/+4e5k6tmBmMd/mTfcOHpqKQsXXJnTTQGwv5ETeLHsEB4PHbFIGVTFpSv5mssIxEzI/KQze4YPGtcjpc3+Jyj85CycVioqBnwDq3o1M63hxjUY7/y4KhjDH/duJqfCCtID7pJDhfpn/tiLlG3E07K+sdfrhS3mJr1+zhU0obK7vrr1u59r89Rqs/PumEOxmp5ZMvWD/jC+LMtxQ22/C5J7yrYMIRgY2osHzGMLcduEt4wTyfmGWdWHOCdqkaWzCI1S+hHKp9kM2pkH/z72siWiuRdvffLk6OPmuHpcD3jH4jHN1ePMij3CdEtqG1mSqC6s6bl9D7cYjf3i4T8p13/1HaT7mTq3clklzIe0FvoaVD2EsvdJVx0syO 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 Wed, 7 Jun 2023 13:53:10 -0700 Mike Kravetz wrote: > > > > BUGs aren't good. Can we please find a way to push this along? > > > > Have we heard anything from any udmabuf people? > > > > I have not heard anything. When this issue popped up, it took me by surprise. > > udmabuf maintainer (Gerd Hoffmann), the people who added hugetlb support and > the list where udmabuf was developed (dri-devel@lists.freedesktop.org) have > been on cc. Maybe Greg can suggest a way forward. > My 'gut reaction' would be to remove hugetlb support from udmabuf. From a > quick look, if we really want this support then there will need to be some > API changes. For example UDMABUF_CREATE should be hugetlb page aligned > and a multiple of hugetlb page size if using a hugetlb mapping. > > It would be good to know about users of the driver. So disabling "hugetlb=on" (and adding an explanatory printk) would suffice for now?