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Date:   Sat, 3 Jun 2023 16:48:10 -0700
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Subject: Re: [PATCH 11/12] selftests/mm: fix missing UFFDIO_CONTINUE_MODE_WP
 and similar build failures
Content-Language: en-US
To:     David Hildenbrand <david@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>
Cc:     Peter Xu <peterx@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>
References: <20230602013358.900637-1-jhubbard@nvidia.com>
 <20230602013358.900637-12-jhubbard@nvidia.com>
 <7a999b80-e266-2b7e-f198-869b1ac7cde7@redhat.com>
 <993773ab-7f5b-241f-b532-ee79a03b371f@nvidia.com>
 <a4fbc191-9acb-5db8-a375-96c0c1ba3fcd@redhat.com>
From:   John Hubbard <jhubbard@nvidia.com>
In-Reply-To: <a4fbc191-9acb-5db8-a375-96c0c1ba3fcd@redhat.com>
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On 6/3/23 01:27, David Hildenbrand wrote:
> On 03.06.23 00:20, John Hubbard wrote:
>> On 6/2/23 03:23, David Hildenbrand wrote:
>> ...
>>> Unfortunately, that seems to be the ugly way to handle this because
>>> including the in-tree headers seems to not work and I yet haven't
>>> figured out why (there were some changes back and forth so I lost track).
>>
>> Yes, ugly, and based on Muhammad's response, I plan on dropping this patch
>> entirely, in fact.
> 
> Ah, finally I know why it sometimes worked and sometimes didn't ... yes, 
> let's document that somehow.
> 
> Maybe we can even warn from the Makefile when the in-tree headers are 
> not installed yet?
> 

Yes. And in fact, after some fooling around getting reacquainted with
selftest Makefiles, it turns out that fussy part was setting up to
detect the missing header files. And that seems to be working reliably
now.

So from there, it's just as easy to automatically build any missing
header files and continue as it is to warn about it.

I'll post a patch.


thanks,
-- 
John Hubbard
NVIDIA