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Date:   Fri, 7 Apr 2023 12:48:32 +0300
From:   Mike Rapoport <rppt@linux.ibm.com>
To:     Peter Xu <peterx@redhat.com>
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        David Hildenbrand <david@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Leonardo Bras Soares Passos <lsoaresp@redhat.com>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>,
        Nadav Amit <nadav.amit@gmail.com>
Subject: Re: [PATCH 11/29] selftests/mm: Drop test_uffdio_zeropage_eexist
Message-ID: <ZC/m8PLFWQ8bGk6q@linux.ibm.com>
References: <20230330155707.3106228-1-peterx@redhat.com>
 <20230330160717.3107010-1-peterx@redhat.com>
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On Thu, Mar 30, 2023 at 12:07:17PM -0400, 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@redhat.com>

Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>

> ---
>  tools/testing/selftests/mm/userfaultfd.c | 20 +++++++++++---------
>  1 file changed, 11 insertions(+), 9 deletions(-)
> 
> diff --git a/tools/testing/selftests/mm/userfaultfd.c b/tools/testing/selftests/mm/userfaultfd.c
> index d724f1c78847..3487ec0bfcc8 100644
> --- a/tools/testing/selftests/mm/userfaultfd.c
> +++ b/tools/testing/selftests/mm/userfaultfd.c
> @@ -88,7 +88,6 @@ static bool test_dev_userfaultfd;
>  /* exercise the test_uffdio_*_eexist every ALARM_INTERVAL_SECS */
>  #define ALARM_INTERVAL_SECS 10
>  static volatile bool test_uffdio_copy_eexist = true;
> -static volatile bool test_uffdio_zeropage_eexist = true;
>  /* Whether to test uffd write-protection */
>  static bool test_uffdio_wp = true;
>  /* Whether to test uffd minor faults */
> @@ -1114,7 +1113,7 @@ static void retry_uffdio_zeropage(int ufd,
>  	}
>  }
> 
> -static int __uffdio_zeropage(int ufd, unsigned long offset, bool retry)
> +static int __uffdio_zeropage(int ufd, unsigned long offset)
>  {
>  	struct uffdio_zeropage uffdio_zeropage;
>  	int ret;
> @@ -1138,11 +1137,8 @@ static int __uffdio_zeropage(int ufd, unsigned long offset, bool retry)
>  		if (res != page_size) {
>  			err("UFFDIO_ZEROPAGE unexpected size");
>  		} else {
> -			if (test_uffdio_zeropage_eexist && retry) {
> -				test_uffdio_zeropage_eexist = false;
> -				retry_uffdio_zeropage(ufd, &uffdio_zeropage,
> -						      offset);
> -			}
> +			retry_uffdio_zeropage(ufd, &uffdio_zeropage,
> +					      offset);
>  			return 1;
>  		}
>  	} else
> @@ -1153,7 +1149,7 @@ static int __uffdio_zeropage(int ufd, unsigned long offset, bool retry)
> 
>  static int uffdio_zeropage(int ufd, unsigned long offset)
>  {
> -	return __uffdio_zeropage(ufd, offset, false);
> +	return __uffdio_zeropage(ufd, offset);
>  }
> 
>  /* exercise UFFDIO_ZEROPAGE */
> @@ -1177,6 +1173,13 @@ static int userfaultfd_zeropage_test(void)
>  	assert_expected_ioctls_present(
>  		uffdio_register.mode, uffdio_register.ioctls);
> 
> +	if (area_dst_alias) {
> +		/* Needed this to test zeropage-retry on shared memory */
> +		uffdio_register.range.start = (unsigned long) area_dst_alias;
> +		if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register))
> +			err("register failure");
> +	}
> +
>  	if (uffdio_zeropage(uffd, 0))
>  		if (my_bcmp(area_dst, zeropage, page_size))
>  			err("zeropage is not zero");
> @@ -1763,7 +1766,6 @@ static void sigalrm(int sig)
>  	if (sig != SIGALRM)
>  		abort();
>  	test_uffdio_copy_eexist = true;
> -	test_uffdio_zeropage_eexist = true;
>  	alarm(ALARM_INTERVAL_SECS);
>  }
> 
> -- 
> 2.39.1
> 

-- 
Sincerely yours,
Mike.