linux-kernel - Re: [PATCH v2 4/4] userfaultfd: selftest: Cope if shmem doesn't support zeropage

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Date:   Tue, 28 Aug 2018 09:15:11 +0300
From:   Mike Rapoport <rppt@...ux.vnet.ibm.com>
To:     Thiago Jung Bauermann <bauerman@...ux.ibm.com>
Cc:     linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
        Shuah Khan <shuah@...nel.org>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Prakash Sangappa <prakash.sangappa@...cle.com>
Subject: Re: [PATCH v2 4/4] userfaultfd: selftest: Cope if shmem doesn't
 support zeropage

On Mon, Aug 27, 2018 at 11:46:33PM -0300, Thiago Jung Bauermann wrote:
> 
> Hello Mike,
> 
> Mike Rapoport <rppt@...ux.vnet.ibm.com> writes:
> 
> > Hi,
> >
> > On Fri, Aug 03, 2018 at 07:00:46PM -0300, Thiago Jung Bauermann wrote:
> >> If userfaultfd runs on a system that doesn't support UFFDIO_ZEROPAGE for
> >> shared memory, it currently ends with error code 1 which indicates test
> >> failure:
> >>
> >>   # ./userfaultfd shmem 10 10
> >>   nr_pages: 160, nr_pages_per_cpu: 80
> >>   bounces: 9, mode: rnd poll, unexpected missing ioctl for anon memory
> >>   # echo $?
> >>   1
> >>
> >> Change userfaultfd_zeropage_test() to return KSFT_SKIP to indicate that
> >> the test is being skipped.
> >
> > I took a deeper look at what userfaultfd_zeropage_test() does and,
> > apparently, I've mislead you. The test checks if the range has
> > UFFDIO_ZEROPAGE and verifies that it works if yes; otherwise the test
> > verifies that EINVAL is returned.
> >
> > Can you please check if the patch below works in your environment?
> >
> > From 7a34c84c0461b5073742275638c44b6535d19166 Mon Sep 17 00:00:00 2001
> > From: Mike Rapoport <rppt@...ux.vnet.ibm.com>
> > Date: Tue, 7 Aug 2018 09:44:19 +0300
> > Subject: [PATCH] userfaultfd: selftest: make supported range ioctl
> >  verification more robust
> >
> > When userfaultfd tests runs on older kernel that does not support
> > UFFDIO_ZEROPAGE for shared memory it fails at the ioctl verification.
> >
> > Split out the verification that supported ioctls are superset of the
> > expected ioctls and relax the checks for UFFDIO_ZEROPAGE for shared memory
> > areas.
> >
> > Signed-off-by: Mike Rapoport <rppt@...ux.vnet.ibm.com>
> > ---
> >  tools/testing/selftests/vm/userfaultfd.c | 63 +++++++++++++++++---------------
> >  1 file changed, 34 insertions(+), 29 deletions(-)
> 
> I'm sorry to take this long to respond, I was only able to get back to
> this today.

No problem :)

> Your patch does solve my problem. Thank you very much!
> 
> It has a trivial conflict in the second hunk with patch 3 in my series.
> Should I repost the series with your patch in place of patch 4?

Yep.
 
> --
> Thiago Jung Bauermann
> IBM Linux Technology Center

-- 
Sincerely yours,
Mike.