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Date:   Fri, 21 Jul 2023 13:29:20 +0200
From:   =?iso-8859-2?Q?Micha=B3_Miros=B3aw?= <mirq-linux@rere.qmqm.pl>
To:     Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc:     Andrei Vagin <avagin@gmail.com>,
        Danylo Mocherniuk <mdanylo@google.com>,
        Alex Sierra <alex.sierra@amd.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Andrew Morton <akpm@linux-foundation.org>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Christian Brauner <brauner@kernel.org>,
        Cyrill Gorcunov <gorcunov@gmail.com>,
        Dan Williams <dan.j.williams@intel.com>,
        David Hildenbrand <david@redhat.com>,
        Greg KH <gregkh@linuxfoundation.org>,
        "Gustavo A . R . Silva" <gustavoars@kernel.org>,
        "Liam R . Howlett" <Liam.Howlett@oracle.com>,
        Matthew Wilcox <willy@infradead.org>,
        =?iso-8859-2?Q?Micha=B3_Miros=B3aw?= <emmir@google.com>,
        Mike Rapoport <rppt@kernel.org>, Nadav Amit <namit@vmware.com>,
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        Yang Shi <shy828301@gmail.com>,
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        kernel@collabora.com
Subject: Re: fs/proc/task_mmu: Implement IOCTL for efficient page table
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On Fri, Jul 21, 2023 at 03:48:22PM +0500, Muhammad Usama Anjum wrote:
> On 7/21/23 12:28 AM, Michał Mirosław wrote:
> > This is a massaged version of patch by Muhammad Usama Anjum [1]
> > to illustrate my review comments and hopefully push the implementation
> > efforts closer to conclusion. The changes are:
> Thank you so much for this effort. I also want to reach conclusion. I'll
> agree with all the changes which don't affect me. But some requirements
> aren't being fulfilled with this current design.
[...]
> #define PAGE_IS_WPASYNC		(1 << 0)
> #define PAGE_IS_WRITTEN		(1 << 1)
> You have another new flag PAGE_IS_WPASYNC. But there is no application of
> PAGE_IS_WPASYNC. We must not add a flag which don't have any user.

BTW, I'm not sure I got the PAGE_IS_WPASYNC naming right - this is to
designate pages that can be write-protected (are UFFD-registered I believe).

Best Regards
Michał Mirosław