Re: [LTP] [PATCH v4 1/4] syscalls/madvise04: new test for madvise(MADV_DONTNEED)

[Richard Palethorpe <rpalethorpe@suse.de>]

Hello,

Zhao Gongyi via ltp <ltp@lists.linux.it> writes:

> Check that madvise(2) MADV_DONTNEED operation applied to Huge
> TLB pages successfully after kernel version 5.18, and will result
> in zero-fill-on-demand pages for anonymous private mappings.
>
> Signed-off-by: Zhao Gongyi <zhaogongyi@huawei.com>
> ---
>  runtest/syscalls                              |  1 +
>  testcases/kernel/syscalls/madvise/.gitignore  |  1 +
>  testcases/kernel/syscalls/madvise/madvise04.c | 62 +++++++++++++++++++
>  3 files changed, 64 insertions(+)
>  create mode 100644 testcases/kernel/syscalls/madvise/madvise04.c
>
> diff --git a/runtest/syscalls b/runtest/syscalls
> index c81764df4..eb1910cec 100644
> --- a/runtest/syscalls
> +++ b/runtest/syscalls
> @@ -941,6 +941,7 @@ mincore04 mincore04
>  madvise01 madvise01
>  madvise02 madvise02
>  madvise03 madvise03
> +madvise04 madvise04
>  madvise05 madvise05
>  madvise06 madvise06
>  madvise07 madvise07
> diff --git a/testcases/kernel/syscalls/madvise/.gitignore b/testcases/kernel/syscalls/madvise/.gitignore
> index f4bfdfefe..db8ce47c1 100644
> --- a/testcases/kernel/syscalls/madvise/.gitignore
> +++ b/testcases/kernel/syscalls/madvise/.gitignore
> @@ -1,6 +1,7 @@
>  /madvise01
>  /madvise02
>  /madvise03
> +/madvise04
>  /madvise05
>  /madvise06
>  /madvise07
> diff --git a/testcases/kernel/syscalls/madvise/madvise04.c b/testcases/kernel/syscalls/madvise/madvise04.c
> new file mode 100644
> index 000000000..a970fb33e
> --- /dev/null
> +++ b/testcases/kernel/syscalls/madvise/madvise04.c
> @@ -0,0 +1,62 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) Huawei Technologies Co., Ltd. 2022. All rights reserved.
> + * Author: Zhao Gongyi <zhaogongyi@huawei.com>
> + */
> +
> +/*\
> + * [Description]
> + *
> + * Check that madvise(2) MADV_DONTNEED operation applied to Huge TLB pages
> + * successfully after kernel version 5.18, and will result in
> + * zero-fill-on-demand pages for anonymous private mappings.
> + */
> +
> +#include "tst_test.h"
> +
> +#define MAP_SIZE (8 * 1024)
> +
> +static char *addr;
> +static int mapsz;
> +
> +static void run(void)
> +{
> +	TST_EXP_PASS(madvise(addr, mapsz, MADV_DONTNEED));
> +	for (int i = 0; i < mapsz; i++) {
> +		if (addr[i]) {
> +			tst_res(TFAIL,
> +				"There are no zero-fill-on-demand pages "
> +				"for anonymous private mappings");
> +			return;
> +		}
> +	}
> +
> +	tst_res(TPASS, "There are zero-fill-on-demand pages "
> +		       "for anonymous private mappings");
> +}
> +
> +static void setup(void)
> +{
> +	mapsz = tst_get_hugepage_size();
> +	addr = SAFE_MMAP(NULL, mapsz,
> +			PROT_READ | PROT_WRITE,
> +			MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB,
> +			-1, 0);
> +	memset(addr, 1, mapsz);

If we only do memset here then we are only testing the zero-fill feature
on the first iteration.

> +}
> +
> +static void cleanup(void)
> +{
> +	if (addr)
> +		SAFE_MUNMAP(addr, mapsz);
> +}
> +
> +static struct tst_test test = {
> +	.test_all = run,
> +	.setup = setup,
> +	.cleanup = cleanup,
> +	.min_kver = "5.18",

What happens before 5.18? Could we try applying MADV_DONTNEED and return
TCONF instead?

> +	.needs_root = 1,

Why does this need root?

> +	.hugepages = {1, TST_NEEDS},
> +};
> +
> --
> 2.17.1


-- 
Thank you,
Richard.

-- 
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