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Date:   Mon, 11 Dec 2023 12:11:23 -0800
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Subject: Re: [PATCH v6 5/5] selftests/mm: add UFFDIO_MOVE ioctl test
To:     Mark Brown <broonie@kernel.org>,
        David Hildenbrand <david@redhat.com>
Cc:     Suren Baghdasaryan <surenb@google.com>, akpm@linux-foundation.org,
        viro@zeniv.linux.org.uk, brauner@kernel.org, shuah@kernel.org,
        aarcange@redhat.com, lokeshgidra@google.com, peterx@redhat.com,
        ryan.roberts@arm.com, hughd@google.com, mhocko@suse.com,
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        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-kselftest@vger.kernel.org, kernel-team@android.com,
        Peter Zijlstra <peterz@infradead.org>
References: <CAJuCfpHRYi4S9c+KKQqtE6Faw1e0E0ENMMRE17zXsqv_CftTGw@mail.gmail.com>
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 <CAJuCfpEcbcO0d5WPDHMqiEJws9k_5c30pE-J+E_VxO_fpTf_mw@mail.gmail.com>
 <3240f4b5-081b-4075-851a-7d1cd86f4333@redhat.com>
 <1368c558-c58c-4574-907e-36b07dee31bb@sirena.org.uk>
 <6ee5d68a-fa54-4ed6-bc41-2bff0d9eb12f@redhat.com>
 <052dc756-cc05-4aa8-9724-14d42853089c@sirena.org.uk>
 <8a2ce635-58f4-44e1-a646-6527936c5836@redhat.com>
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From:   John Hubbard <jhubbard@nvidia.com>
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On 12/11/23 12:01, Mark Brown wrote:
> On Mon, Dec 11, 2023 at 07:00:32PM +0100, David Hildenbrand wrote:
>> On 11.12.23 18:32, Mark Brown wrote:
>>> On Mon, Dec 11, 2023 at 05:53:59PM +0100, David Hildenbrand wrote:
> 
>>>> https://lkml.kernel.org/r/20231209020144.244759-1-jhubbard@nvidia.com
> 
>>> I mean, I guess people who don't want to install the headers are just
>>> not going to be able to build a bunch of tests?  There definitely are a
>>> bunch of tests where it's not needed so I can see why people would not
>>> like being forced to do the headers step if they're only interested in
>>> those tests.
> 
>> Yes. And before that, people mostly had no clue that headers had to be
>> installed in order to compile successfully.
> 
>> So maybe a warning to give at least some hint might be reasonable.
> 
> That sounds sensible, especially if we could arrange to flag when the
> specific tests being built need it.


But the end result is messy: not everything builds in some cases. If
instead we went back to the little ifdef snippets, such as this (from
v5.1):

hugepage-shm.c:

     #ifndef SHM_HUGETLB
     #define SHM_HUGETLB 04000
     #endif

...then with a bit of one-time, manual effort, we could get everything
to work at all times. And that seems better, doesn't it?


thanks,
-- 
John Hubbard
NVIDIA