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[211.29.132.246]) by mx.google.com with ESMTP id t24si32634478pgu.221.2019.07.31.03.22.04 for ; Wed, 31 Jul 2019 03:22:04 -0700 (PDT) Received-SPF: neutral (google.com: 211.29.132.246 is neither permitted nor denied by best guess record for domain of david@fromorbit.com) client-ip=211.29.132.246; Authentication-Results: mx.google.com; spf=neutral (google.com: 211.29.132.246 is neither permitted nor denied by best guess record for domain of david@fromorbit.com) smtp.mailfrom=david@fromorbit.com Received: from dread.disaster.area (pa49-195-139-63.pa.nsw.optusnet.com.au [49.195.139.63]) by mail104.syd.optusnet.com.au (Postfix) with ESMTPS id E23D943E0B2; Wed, 31 Jul 2019 20:22:00 +1000 (AEST) Received: from dave by dread.disaster.area with local (Exim 4.92) (envelope-from ) id 1hslj3-0005u5-Se; Wed, 31 Jul 2019 20:20:53 +1000 Date: Wed, 31 Jul 2019 20:20:53 +1000 From: Dave Chinner To: William Kucharski Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Dave Hansen , Song Liu , Bob Kasten , Mike Kravetz , Chad Mynhier , "Kirill A. Shutemov" , Johannes Weiner , Matthew Wilcox Subject: Re: [PATCH v3 0/2] mm,thp: Add filemap_huge_fault() for THP Message-ID: <20190731102053.GZ7689@dread.disaster.area> References: <20190731082513.16957-1-william.kucharski@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190731082513.16957-1-william.kucharski@oracle.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.2 cv=D+Q3ErZj c=1 sm=1 tr=0 cx=a_idp_d a=fNT+DnnR6FjB+3sUuX8HHA==:117 a=fNT+DnnR6FjB+3sUuX8HHA==:17 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=kj9zAlcOel0A:10 a=0o9FgrsRnhwA:10 a=7-415B0cAAAA:8 a=BDTIUSf9NILoYbXAtJgA:9 a=CjuIK1q_8ugA:10 a=biEYGPWJfzWAr4FL6Ov7:22 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, Jul 31, 2019 at 02:25:11AM -0600, William Kucharski wrote: > This set of patches is the first step towards a mechanism for automatically > mapping read-only text areas of appropriate size and alignment to THPs > whenever possible. > > For now, the central routine, filemap_huge_fault(), amd various support > routines are only included if the experimental kernel configuration option > > RO_EXEC_FILEMAP_HUGE_FAULT_THP > > is enabled. > > This is because filemap_huge_fault() is dependent upon the > address_space_operations vector readpage() pointing to a routine that will > read and fill an entire large page at a time without poulluting the page > cache with PAGESIZE entries How is the readpage code supposed to stuff a THP page into a bio? i.e. Do bio's support huge pages, and if not, what is needed to stuff a huge page in a bio chain? Once you can answer that question, you should be able to easily convert the iomap_readpage/iomap_readpage_actor code to support THP pages without having to care about much else as iomap_readpage() is already coded in a way that will iterate IO over the entire THP for you.... Cheers, Dave. -- Dave Chinner david@fromorbit.com