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From:   Yuanchu Xie <yuanchu@google.com>
Date:   Mon, 16 May 2022 21:07:25 -0400
Message-ID: <CAJj2-QGk9DmGhjPsjHwL5uj+cQs6=12iKEffpq+Vxv3=CrMPBA@mail.gmail.com>
Subject: Re: [PATCH v3] selftests/damon: suppress compiler warnings for huge_count_read_write
To:     SeongJae Park <sj@kernel.org>
Cc:     Shuah Khan <shuah@kernel.org>, Markus Boehme <markubo@amazon.de>,
        David Rientjes <rientjes@google.com>,
        Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org
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SeongJae,

Do you have a preference on how this should be handled?

Thanks,
Yuanchu

On Wed, May 4, 2022 at 6:12 PM Yuanchu Xie <yuanchu@google.com> wrote:
>
> Hi SeongJae,
>
> On Wed, May 4, 2022 at 11:45 AM SeongJae Park <sj@kernel.org> wrote:
> >
> > Hi Yuanchu,
> >
> > On Wed, 4 May 2022 18:29:08 +0000 Yuanchu Xie <yuanchu@google.com> wrot=
e:
> >
> > > The test case added in commit db7a347b26fe ("mm/damon/dbgfs:
> > > use '__GFP_NOWARN' for user-specified size buffer allocation")
> > > intentionally writes and reads with a large count to cause
> > > allocation failure and check for kernel warnings. We suppress
> > > the compiler warnings for these calls as they work as intended.
> > >
> > > Signed-off-by: Yuanchu Xie <yuanchu@google.com>
> > > ---
> >
> > It would be a good practice to mention the changes from the previous ve=
rsion of
> > this patch here[1].
> >
> > [1] https://docs.kernel.org/process/submitting-patches.html#the-canonic=
al-patch-format
> >
> Thank you, I missed this when trying to figure out how to add
> additional comments for a revision.
>
> > >  tools/testing/selftests/damon/huge_count_read_write.c | 2 ++
> > >  1 file changed, 2 insertions(+)
> > >
> > > diff --git a/tools/testing/selftests/damon/huge_count_read_write.c b/=
tools/testing/selftests/damon/huge_count_read_write.c
> > > index ad7a6b4cf338..91bd80c75cd9 100644
> > > --- a/tools/testing/selftests/damon/huge_count_read_write.c
> > > +++ b/tools/testing/selftests/damon/huge_count_read_write.c
> > > @@ -2,6 +2,8 @@
> > >  /*
> > >   * Author: SeongJae Park <sj@kernel.org>
> > >   */
> > > +#pragma GCC diagnostic ignored "-Wstringop-overflow"
> > > +#pragma GCC diagnostic ignored "-Wstringop-overread"
> >
> > I agree that this must be the cleaner way than v2.  But, I get below wa=
rning
> > after applying this:
> >
> >     $ sudo make -C tools/testing/selftests/damon run_tests
> >     make: Entering directory '/home/sjpark/linux/tools/testing/selftest=
s/damon'
> >     gcc     huge_count_read_write.c  -o /home/sjpark/linux/tools/testin=
g/selftests/damon/huge_count_read_write
> >     huge_count_read_write.c:6:32: warning: unknown option after =E2=80=
=98#pragma GCC diagnostic=E2=80=99 kind [-Wpragmas]
> >         6 | #pragma GCC diagnostic ignored "-Wstringop-overread"
> >           |                                ^~~~~~~~~~~~~~~~~~~~~
> >
> > My gcc version is:
> >
> >     $ gcc --version
> >     gcc (Ubuntu 9.4.0-1ubuntu1~20.04.1) 9.4.0
> I see, I'm running
>
>     $ gcc --version
>     gcc (Debian 11.2.0-16+build1) 11.2.0
>
> I believe this is a new warning for gcc-11 [1], and somewhat
> unfortunate that it results in a warning for gcc-9.4. I'm not sure
> what the preference is here.
> [1] https://gcc.gnu.org/onlinedocs/gcc-10.3.0/gcc/Warning-Options.html
>
> Thanks,
> Yuanchu