Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH v5 3/9] mm: Add write-protect and clean utilities for
 address space ranges
To:     Christoph Hellwig <hch@infradead.org>
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 <thellstrom@vmware.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Matthew Wilcox <willy@infradead.org>,
        Will Deacon <will.deacon@arm.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Rik van Riel <riel@surriel.com>,
        Minchan Kim <minchan@kernel.org>,
        Michal Hocko <mhocko@suse.com>,
        Huang Ying <ying.huang@intel.com>,
        Souptick Joarder <jrdr.linux@gmail.com>,
        =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= <jglisse@redhat.com>,
        linux-mm@kvack.org, Ralph Campbell <rcampbell@nvidia.com>
References: <20190612064243.55340-1-thellstrom@vmwopensource.org>
 <20190612064243.55340-4-thellstrom@vmwopensource.org>
 <20190612112349.GA20226@infradead.org>
From:   =?UTF-8?Q?Thomas_Hellstr=c3=b6m_=28VMware=29?= 
        <thellstrom@vmwopensource.org>
Organization: VMware Inc.
Message-ID: <a004e1a5-bdc5-6508-039e-8d97a9d3cb68@vmwopensource.org>
Date:   Wed, 12 Jun 2019 14:20:03 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.6.1
MIME-Version: 1.0
In-Reply-To: <20190612112349.GA20226@infradead.org>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 8bit
Content-Language: en-US
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 6/12/19 1:23 PM, Christoph Hellwig wrote:
> On Wed, Jun 12, 2019 at 08:42:37AM +0200, Thomas Hellström (VMware) wrote:
>> From: Thomas Hellstrom <thellstrom@vmware.com>
>>
>> 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.

Sounds reasonable if this uses already EXPORT_SYMBOL_GPL'd 
functionality. I'll respin.

>    Also in general new core functionality like this should go
> along with the actual user, we don't need to repeat the hmm disaster.

I see in your later message that you noticed the other patches. There's 
also user-space functionality in mesa that excercises this.

/Thomas