linux-kernel - Re: [PATCH 11/29] selftests/mm: Drop test_uffdio_zeropage

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Message-ID: <20230401000317.GF12460@monkey>
Date:   Fri, 31 Mar 2023 17:03:17 -0700
From:   Mike Kravetz <mike.kravetz@...cle.com>
To:     Peter Xu <peterx@...hat.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        David Hildenbrand <david@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Leonardo Bras Soares Passos <lsoaresp@...hat.com>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Nadav Amit <nadav.amit@...il.com>
Subject: Re: [PATCH 11/29] selftests/mm: Drop test_uffdio_zeropage_eexist

On 03/30/23 12:07, Peter Xu wrote:
> The idea was trying to flip this var in the alarm handler from time to time
> to test -EEXIST of UFFDIO_ZEROPAGE, but firstly it's only used in the
> zeropage test so probably only used once, meanwhile we passed
> "retry==false" so it'll never got tested anyway.
> 
> Drop both sides so we always test UFFDIO_ZEROPAGE retries if has_zeropage
> is set (!hugetlb).
> 
> One more thing to do is doing UFFDIO_REGISTER for the alias buffer too,
> because otherwise the test won't even pass!  We were just lucky that this
> test never really got ran at all.
> 
> Signed-off-by: Peter Xu <peterx@...hat.com>
> ---
>  tools/testing/selftests/mm/userfaultfd.c | 20 +++++++++++---------
>  1 file changed, 11 insertions(+), 9 deletions(-)

Thanks!  With only passing "retry==false", that code is indeed dead.  I had
to read the code again to understand area_dst_alias.  Thanks for taking this
on as the code is difficult to understand.

Reviewed-by: Mike Kravetz <mike.kravetz@...cle.com>
-- 
Mike Kravetz