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Subject: Re: [PATCH 1/2] mm: introduce put_user_page*(), placeholder versions
To:     Mike Rapoport <rppt@linux.ibm.com>, <john.hubbard@gmail.com>
CC:     Andrew Morton <akpm@linux-foundation.org>, <linux-mm@kvack.org>,
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References: <20190208075649.3025-1-jhubbard@nvidia.com>
 <20190208075649.3025-2-jhubbard@nvidia.com>
 <20190208103211.GD11096@rapoport-lnx>
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From:   John Hubbard <jhubbard@nvidia.com>
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Date:   Fri, 8 Feb 2019 12:44:48 -0800
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On 2/8/19 2:32 AM, Mike Rapoport wrote:
> On Thu, Feb 07, 2019 at 11:56:48PM -0800, john.hubbard@gmail.com wrote:
>> From: John Hubbard <jhubbard@nvidia.com>
[...]
>> +/**
>> + * put_user_page() - release a gup-pinned page
>> + * @page:            pointer to page to be released
>> + *
>> + * Pages that were pinned via get_user_pages*() must be released via
>> + * either put_user_page(), or one of the put_user_pages*() routines
>> + * below. This is so that eventually, pages that are pinned via
>> + * get_user_pages*() can be separately tracked and uniquely handled. In
>> + * particular, interactions with RDMA and filesystems need special
>> + * handling.
>> + *
>> + * put_user_page() and put_page() are not interchangeable, despite this early
>> + * implementation that makes them look the same. put_user_page() calls must
> 
> I just hope we'll remember to update when the real implementation will be
> merged ;-)
> 
> Other than that, feel free to add
> 
> Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>	# docs
> 

Thanks for the review!

Yes, the follow-on patch that turns this into a real implementation is
posted [1], and its documentation is updated accordingly.

(I've already changed "@Returns" to "@Return" locally in that patch, btw.)

[1] https://lore.kernel.org/r/20190204052135.25784-5-jhubbard@nvidia.com

thanks,
-- 
John Hubbard
NVIDIA