linux-kernel - Re: [PATCH v3 30/48] mm/damon: Stop using vma_mas

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Message-ID: <20230117224734.c4lo4spezufwsims@revolver>
Date:   Tue, 17 Jan 2023 22:47:36 +0000
From:   Liam Howlett <liam.howlett@...cle.com>
To:     Daniel Latypov <dlatypov@...gle.com>
CC:     SeongJae Park <sj@...nel.org>,
        "brendanhiggins@...gle.com" <brendanhiggins@...gle.com>,
        "kunit-dev@...glegroups.com" <kunit-dev@...glegroups.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>,
        "damon@...ts.linux.dev" <damon@...ts.linux.dev>,
        kernel test robot <lkp@...el.com>
Subject: Re: [PATCH v3 30/48] mm/damon: Stop using vma_mas_store() for maple
 tree store

* Daniel Latypov <dlatypov@...gle.com> [230117 17:20]:
> On Tue, Jan 17, 2023 at 11:11 AM SeongJae Park <sj@...nel.org> wrote:
> >
> > Cc-ing kunit people.
> >
> > Hi Liam,
> >
> >
> > Could we put touching file name on the summary?
> > E.g., mm/damon/vaddr-test: Stop using ...
> >
> > On Tue, 17 Jan 2023 02:34:19 +0000 Liam Howlett <liam.howlett@...cle.com> wrote:
> >
> > > From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
> > >
> > > Prepare for the removal of the vma_mas_store() function by open coding
> > > the maple tree store in this test code.  Set the range of the maple
> > > state and call the store function directly.
> > >
> > > Cc: SeongJae Park <sj@...nel.org>
> > > Cc: damon@...ts.linux.dev
> > > Reported-by: kernel test robot <lkp@...el.com>
> > > Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
> > > ---
> > >  mm/damon/vaddr-test.h | 19 +++++++++++++------
> > >  1 file changed, 13 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/mm/damon/vaddr-test.h b/mm/damon/vaddr-test.h
> > > index bce37c487540..6098933d3272 100644
> > > --- a/mm/damon/vaddr-test.h
> > > +++ b/mm/damon/vaddr-test.h
> > > @@ -14,19 +14,26 @@
> > >
> > >  #include <kunit/test.h>
> > >
> > > -static void __link_vmas(struct maple_tree *mt, struct vm_area_struct *vmas,
> > > +static int __link_vmas(struct maple_tree *mt, struct vm_area_struct *vmas,
> > >                       ssize_t nr_vmas)
> > >  {
> > > -     int i;
> > > +     int i, ret = -ENOMEM;
> > >       MA_STATE(mas, mt, 0, 0);
> > >
> > >       if (!nr_vmas)
> > > -             return;
> > > +             return -ENOENT;
> 
> We could pass in the `test` object here and give more detailed info, e.g.
>   (if !nr_vmas)
>      kunit_skip(test, "...");
> 
> And below could be
> 
> bool stored_all = false; // instead of ret
> ...
> for (...) {
> 
> }
> stored_all = true;
> 
> failed:
>   mas_unlock(&mas);
>   if (!stored_all) kunit_skip(test, "failed to...");
> 
> > >
> > >       mas_lock(&mas);
> > > -     for (i = 0; i < nr_vmas; i++)
> > > -             vma_mas_store(&vmas[i], &mas);
> > > +     for (i = 0; i < nr_vmas; i++) {
> > > +             mas_set_range(&mas, vmas[i].vm_start, vmas[i].vm_end - 1);
> > > +             if (mas_store_gfp(&mas, &vmas[i], GFP_KERNEL))
> > > +                     goto failed;
> > > +     }
> > > +     ret = 0;
> > > +
> > > +failed:
> > >       mas_unlock(&mas);
> > > +     return ret;
> > >  }
> > >
> > >  /*
> > > @@ -71,7 +78,7 @@ static void damon_test_three_regions_in_vmas(struct kunit *test)
> > >       };
> > >
> > >       mt_init_flags(&mm.mm_mt, MM_MT_FLAGS);
> > > -     __link_vmas(&mm.mm_mt, vmas, ARRAY_SIZE(vmas));
> > > +     KUNIT_EXPECT_EQ(test, __link_vmas(&mm.mm_mt, vmas, ARRAY_SIZE(vmas)), 0);
> >
> > In case of the __link_vmas() failure, I think we should skip this test using
> > 'kunit_skip()', rather marking this test failed.
> 
> As noted above, I'd suggest we also pass in the `test` object to
> __link_vmas() and call kunit_skip() from there.

My thoughts were if we are testing adding nothing to the list, then
there is probably a problem with the test and so that should be
highlighted with a failure.

I really don't mind either way.