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[2607:7c80:54:e::133]) by mx.google.com with ESMTPS id q4si16238615pfb.272.2019.06.12.04.24.16 for (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Wed, 12 Jun 2019 04:24:16 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of batv+eeb336ffa9092f1fc134+5771+infradead.org+hch@bombadil.srs.infradead.org designates 2607:7c80:54:e::133 as permitted sender) client-ip=2607:7c80:54:e::133; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=pu7FtOXG; spf=pass (google.com: best guess record for domain of batv+eeb336ffa9092f1fc134+5771+infradead.org+hch@bombadil.srs.infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=BATV+eeb336ffa9092f1fc134+5771+infradead.org+hch@bombadil.srs.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Transfer-Encoding :Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=KJAXvYM0DI4vnD/0tu+larrshBV1A0aACdJmWI9kxzw=; b=pu7FtOXG6wwPz8NJqGleP0ENqZ mWOWq7bfIS7I5pJndBO7Iorv4+OVLhztJH0MIESlmLmmGgHrX5hLbLEBOu5/+LynDGtoTdbcUkwHz m+0nmPp8W2Zntos4QTutZ9PdRPfjOaERnezAPGG3G6HwOydPr0nIyh6ofXteGyBhSrbeCM90amEhl OvRad6uKCL5pbwCDcWfUThMqxLI35Q+Iv2FUvjxoK6yPof3pP/uGWUbgh7SyFzGn2D06ZiXnMuLmo FR8QqLtcf0RpwhAoW7YZQpMmHjkcYzS44RCzNLkzUQGIM1bRdNtGmin0BBuQtePw75gHO3CRPmO21 BHvzeyqQ==; Received: from hch by bombadil.infradead.org with local (Exim 4.92 #3 (Red Hat Linux)) id 1hb1M6-0005io-1P; Wed, 12 Jun 2019 11:23:50 +0000 Date: Wed, 12 Jun 2019 04:23:50 -0700 From: Christoph Hellwig To: Thomas =?iso-8859-1?Q?Hellstr=F6m_=28VMware=29?= Cc: dri-devel@lists.freedesktop.org, linux-graphics-maintainer@vmware.com, pv-drivers@vmware.com, linux-kernel@vger.kernel.org, nadav.amit@gmail.com, Thomas Hellstrom , Andrew Morton , Matthew Wilcox , Will Deacon , Peter Zijlstra , Rik van Riel , Minchan Kim , Michal Hocko , Huang Ying , Souptick Joarder , =?iso-8859-1?B?Suly9G1l?= Glisse , linux-mm@kvack.org, Ralph Campbell Subject: Re: [PATCH v5 3/9] mm: Add write-protect and clean utilities for address space ranges Message-ID: <20190612112349.GA20226@infradead.org> References: <20190612064243.55340-1-thellstrom@vmwopensource.org> <20190612064243.55340-4-thellstrom@vmwopensource.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190612064243.55340-4-thellstrom@vmwopensource.org> User-Agent: Mutt/1.11.4 (2019-03-13) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html 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, Jun 12, 2019 at 08:42:37AM +0200, Thomas Hellström (VMware) wrote: > From: Thomas Hellstrom > > Add two utilities to a) write-protect and b) clean all ptes pointing into > a range of an address space. > The utilities are intended to aid in tracking dirty pages (either > driver-allocated system memory or pci device memory). > The write-protect utility should be used in conjunction with > page_mkwrite() and pfn_mkwrite() to trigger write page-faults on page > accesses. Typically one would want to use this on sparse accesses into > large memory regions. The clean utility should be used to utilize > hardware dirtying functionality and avoid the overhead of page-faults, > typically on large accesses into small memory regions. Please use EXPORT_SYMBOL_GPL, just like for apply_to_page_range and friends. Also in general new core functionality like this should go along with the actual user, we don't need to repeat the hmm disaster.