linux-kernel - Re: [PATCH v2 1/2] mm/migrate: Fix read-only page got writable when recover pte

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Message-ID: <Y3PWP9RPjg5FObMN@x1n>
Date:   Tue, 15 Nov 2022 13:11:11 -0500
From:   Peter Xu <peterx@...hat.com>
To:     David Hildenbrand <david@...hat.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Andrea Arcangeli <aarcange@...hat.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Ives van Hoorne <ives@...esandbox.io>,
        Nadav Amit <nadav.amit@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>, stable@...r.kernel.org
Subject: Re: [PATCH v2 1/2] mm/migrate: Fix read-only page got writable when
 recover pte

On Tue, Nov 15, 2022 at 06:54:09PM +0100, David Hildenbrand wrote:
> No it isn't natural. But sneaking such a change into your fix seems wrong.
> Touching !uffd-wp code should be separate, if we want to do this at all (as
> we discussed, maybe the better/cleaner approach is to eliminate writable
> migration entries if possible).

If you see I made the subject as mm/migrate, because I took it as a
migration change, not uffd-wp specific.  I also added the Fixes to the uffd
patch because afaict that's the only thing that it affects, but I can't
tell either.

As I said, I'm trying to follow the rule where we have read entry I want to
make sure write bit removed.

I hope we have this patch land soon, because it affects users.  I'm not
against further rework on migration entries as I replied in the other
email, but for this patch I keep the same thoughts as when I posted.

Thanks,

-- 
Peter Xu