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Date:   Thu, 8 Dec 2022 15:21:55 -0500
From:   Peter Xu <peterx@redhat.com>
To:     David Hildenbrand <david@redhat.com>
Cc:     linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Ives van Hoorne <ives@codesandbox.io>,
        stable@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>,
        Hugh Dickins <hugh@veritas.com>,
        Alistair Popple <apopple@nvidia.com>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>,
        Nadav Amit <nadav.amit@gmail.com>,
        Andrea Arcangeli <aarcange@redhat.com>
Subject: Re: [PATCH v1] mm/userfaultfd: enable writenotify while
 userfaultfd-wp is enabled for a VMA
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References: <20221208114137.35035-1-david@redhat.com>
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On Thu, Dec 08, 2022 at 03:06:06PM -0500, Peter Xu wrote:
> On Thu, Dec 08, 2022 at 05:44:35PM +0100, David Hildenbrand wrote:
> > I'll wait for some more (+retest) before I resend tomorrow.
> 
> One more thing just to double check:
> 
> It's 6a56ccbcf6c6 ("mm/autonuma: use can_change_(pte|pmd)_writable() to
> replace savedwrite", 2022-11-30) that just started to break uffd-wp on
> numa, am I right?
> 
> With the old code, pte_modify() will persist uffd-wp bit, afaict, and we
> used to do savedwrite for numa hints.  That all look correct to me until
> the savedwrite removal patchset with/without vm_page_prot changes.
> 
> If that's the case, we'd better also mention that in the commit message and
> has another Fixes: for that one to be clear.

Nah, never mind.  I think the savedwrite will not guarantee pte write
protected just like the migration path.  The commit message is correct.

-- 
Peter Xu