linux-kernel - Re: [PATCH v2 15/26] userfaultfd: wp: drop _PAGE_UFFD

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Message-ID: <20190222153615.GF7783@redhat.com>
Date:   Fri, 22 Feb 2019 10:36:15 -0500
From:   Jerome Glisse <jglisse@...hat.com>
To:     Peter Xu <peterx@...hat.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        David Hildenbrand <david@...hat.com>,
        Hugh Dickins <hughd@...gle.com>,
        Maya Gokhale <gokhale2@...l.gov>,
        Pavel Emelyanov <xemul@...tuozzo.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Martin Cracauer <cracauer@...s.org>, Shaohua Li <shli@...com>,
        Marty McFadden <mcfadden8@...l.gov>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Denis Plotnikov <dplotnikov@...tuozzo.com>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Mel Gorman <mgorman@...e.de>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        "Dr . David Alan Gilbert" <dgilbert@...hat.com>
Subject: Re: [PATCH v2 15/26] userfaultfd: wp: drop _PAGE_UFFD_WP properly
 when fork

On Fri, Feb 22, 2019 at 05:09:19PM +0800, Peter Xu wrote:
> On Thu, Feb 21, 2019 at 01:06:31PM -0500, Jerome Glisse wrote:
> > On Tue, Feb 12, 2019 at 10:56:21AM +0800, Peter Xu wrote:
> > > UFFD_EVENT_FORK support for uffd-wp should be already there, except
> > > that we should clean the uffd-wp bit if uffd fork event is not
> > > enabled.  Detect that to avoid _PAGE_UFFD_WP being set even if the VMA
> > > is not being tracked by VM_UFFD_WP.  Do this for both small PTEs and
> > > huge PMDs.
> > > 
> > > Signed-off-by: Peter Xu <peterx@...hat.com>
> > 
> > This patch must be earlier in the serie, before the patch that introduce
> > the userfaultfd API so that bisect can not end up on version where this
> > can happen.
> 
> Yes it should be now? Since the API will be introduced until patch
> 21/26 ("userfaultfd: wp: add the writeprotect API to userfaultfd
> ioctl").

No i was confuse when reading this patch i had the feeling it was
after the ioctl ignore my comment.

> 
> > 
> > Otherwise the patch itself is:
> > 
> > Reviewed-by: Jérôme Glisse <jglisse@...hat.com>
> 
> Unless I found anything I've missed above... I'll temporarily pick
> this R-b for now then.

It is fine, the patch ordering was my confusion.

Cheers,
Jérôme