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Date:   Fri, 2 Jun 2023 18:38:29 -0400
From:   Peter Xu <peterx@redhat.com>
To:     John Hubbard <jhubbard@nvidia.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        David Hildenbrand <david@redhat.com>,
        Shuah Khan <shuah@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>, linux-mm@kvack.org,
        linux-kselftest@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 10/12] selftests/mm: move uffd* routines from vm_util.c
 to uffd-common.c
Message-ID: <ZHpvZcdik7VPsEcL@x1n>
References: <20230602013358.900637-1-jhubbard@nvidia.com>
 <20230602013358.900637-11-jhubbard@nvidia.com>
 <ZHoR+3v+zUENBhi4@x1n>
 <68549f29-fe41-04d4-f648-245f399c350b@nvidia.com>
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On Fri, Jun 02, 2023 at 03:11:52PM -0700, John Hubbard wrote:
> On 6/2/23 08:59, Peter Xu wrote:
> > On Thu, Jun 01, 2023 at 06:33:56PM -0700, John Hubbard wrote:
> > > This is where they belong, and this makes it cleaner to apply a
> > > follow-up fix to the uffd builds.
> > > 
> > > Signed-off-by: John Hubbard <jhubbard@nvidia.com>
> > 
> > Thanks for further looking into this.
> > 
> > I'm fine to move it over if you think proper, but just to mention I had
> > those in vm_utils.h just because I left all uffd specific tests shared code
> > in uffd-common.h, so my plan was uffd-common.h shouldn't be included in
> > most test cases except uffd tests.
> 
> I think we're in agreement that we want to only include uffd-common.h
> where it's actually required. Likewise with the uffd*() routines. So I
> would like to still move this over, yes, just to have things in their
> best-named location.

Sorry I didn't get it - e.g. I'm confused why we need to export
uffd_test_ops into ksm unit test, it doesn't make much sense to me..

If you think vm_util.h is a name too common to contain uffd helpers, shall
we create another vm_util_uffd.h just to put the uffd helpers?

Just see what's there in uffd-common.h, which is still ugly (I could look
into it some other day):

extern unsigned long nr_cpus, nr_pages, nr_pages_per_cpu, page_size;
extern char *area_src, *area_src_alias, *area_dst, *area_dst_alias, *area_remap;
extern int uffd, uffd_flags, finished, *pipefd, test_type;
extern bool map_shared;
extern bool test_uffdio_wp;
extern unsigned long long *count_verify;
extern volatile bool test_uffdio_copy_eexist;

extern uffd_test_ops_t anon_uffd_test_ops;
extern uffd_test_ops_t shmem_uffd_test_ops;
extern uffd_test_ops_t hugetlb_uffd_test_ops;
extern uffd_test_ops_t *uffd_test_ops;

and more.

That's why I think this header should not better be included by anyone else
besides uffd-stress.c and uffd-unit-tests.c for now.

> 
> > 
> > I'm not sure whether we can just make your next patch of "ifndef.." into
> > vm_utils.h to avoid the movement, or is it a must?
> > 
> 
> Actually, I think I can drop the next patch entirely, based on
> Muhammad's observation that we should be doing a "make headers"
> to pull in those items. I'll have more to say over on that thread.

Sure, great if the local headers will work.  Thanks.

-- 
Peter Xu