linux-kernel - Re: [PATCH v5 5/5] selftests/mm: add UFFDIO

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Date:   Fri, 1 Dec 2023 09:29:23 +0000
From:   Ryan Roberts <ryan.roberts@....com>
To:     Suren Baghdasaryan <surenb@...gle.com>, akpm@...ux-foundation.org
Cc:     viro@...iv.linux.org.uk, brauner@...nel.org, shuah@...nel.org,
        aarcange@...hat.com, lokeshgidra@...gle.com, peterx@...hat.com,
        david@...hat.com, hughd@...gle.com, mhocko@...e.com,
        axelrasmussen@...gle.com, rppt@...nel.org, willy@...radead.org,
        Liam.Howlett@...cle.com, jannh@...gle.com, zhangpeng362@...wei.com,
        bgeffon@...gle.com, kaleshsingh@...gle.com, ngeoffray@...gle.com,
        jdduke@...gle.com, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org, kernel-team@...roid.com
Subject: Re: [PATCH v5 5/5] selftests/mm: add UFFDIO_MOVE ioctl test

On 21/11/2023 17:16, Suren Baghdasaryan wrote:
> Add tests for new UFFDIO_MOVE ioctl which uses uffd to move source
> into destination buffer while checking the contents of both after
> the move. After the operation the content of the destination buffer
> should match the original source buffer's content while the source
> buffer should be zeroed. Separate tests are designed for PMD aligned and
> unaligned cases because they utilize different code paths in the kernel.
> 
> Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>
> ---
>  tools/testing/selftests/mm/uffd-common.c     |  24 +++
>  tools/testing/selftests/mm/uffd-common.h     |   1 +
>  tools/testing/selftests/mm/uffd-unit-tests.c | 189 +++++++++++++++++++
>  3 files changed, 214 insertions(+)
> 
> diff --git a/tools/testing/selftests/mm/uffd-common.c b/tools/testing/selftests/mm/uffd-common.c
> index fb3bbc77fd00..b0ac0ec2356d 100644
> --- a/tools/testing/selftests/mm/uffd-common.c
> +++ b/tools/testing/selftests/mm/uffd-common.c
> @@ -631,6 +631,30 @@ int copy_page(int ufd, unsigned long offset, bool wp)
>  	return __copy_page(ufd, offset, false, wp);
>  }
>  
> +int move_page(int ufd, unsigned long offset, unsigned long len)
> +{
> +	struct uffdio_move uffdio_move;
> +
> +	if (offset + len > nr_pages * page_size)
> +		err("unexpected offset %lu and length %lu\n", offset, len);
> +	uffdio_move.dst = (unsigned long) area_dst + offset;
> +	uffdio_move.src = (unsigned long) area_src + offset;
> +	uffdio_move.len = len;
> +	uffdio_move.mode = UFFDIO_MOVE_MODE_ALLOW_SRC_HOLES;
> +	uffdio_move.move = 0;
> +	if (ioctl(ufd, UFFDIO_MOVE, &uffdio_move)) {
> +		/* real retval in uffdio_move.move */
> +		if (uffdio_move.move != -EEXIST)
> +			err("UFFDIO_MOVE error: %"PRId64,
> +			    (int64_t)uffdio_move.move);

Hi Suren,

FYI this error is triggering in mm-unstable (715b67adf4c8):

Testing move-pmd on anon... ERROR: UFFDIO_MOVE error: -16 (errno=16,
@uffd-common.c:648)

I'm running in a VM on Apple M2 (arm64). I haven't debugged any further, but
happy to go deeper if you can direct.

Thanks,
Ryan


> +		wake_range(ufd, uffdio_move.dst, len);
> +	} else if (uffdio_move.move != len) {
> +		err("UFFDIO_MOVE error: %"PRId64, (int64_t)uffdio_move.move);
> +	} else
> +		return 1;
> +	return 0;
> +}