Re: [LTP] [PATCH v1 3/3] Add process_madvise03 test

[Richard Palethorpe <rpalethorpe@suse.de>]

Hello,

Andrea Cervesato via ltp <ltp@lists.linux.it> writes:

> Test for checking MADV_PAGEOUT functionality over memory-mapped file
> in process_madvise syscall.

So this one doesn't need swap, but it has some other issues.

>
> Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>
> ---
>  testcases/kernel/syscalls/cma/.gitignore      |   1 +
>  .../kernel/syscalls/cma/process_madvise03.c   | 139 ++++++++++++++++++
>  2 files changed, 140 insertions(+)
>  create mode 100644 testcases/kernel/syscalls/cma/process_madvise03.c
>
> diff --git a/testcases/kernel/syscalls/cma/.gitignore b/testcases/kernel/syscalls/cma/.gitignore
> index 47ae3e445..147b03c48 100644
> --- a/testcases/kernel/syscalls/cma/.gitignore
> +++ b/testcases/kernel/syscalls/cma/.gitignore
> @@ -4,3 +4,4 @@
>  /process_vm_writev02
>  /process_madvise01
>  /process_madvise02
> +/process_madvise03
> diff --git a/testcases/kernel/syscalls/cma/process_madvise03.c b/testcases/kernel/syscalls/cma/process_madvise03.c
> new file mode 100644
> index 000000000..3f12ef530
> --- /dev/null
> +++ b/testcases/kernel/syscalls/cma/process_madvise03.c
> @@ -0,0 +1,139 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (C) 2022 SUSE LLC Andrea Cervesato <andrea.cervesato@suse.com>
> + */
> +
> +/*\
> + * [Description]
> + *
> + * Spawn child inside cgroup and set max memory. Allocate file-backed memory
> + * pages inside child and reclaim it with MADV_PAGEOUT. Then check if memory
> + * pages have been written back to the backing storage.
> + *
> + * The advice might be ignored for some pages in the range when it is
> + * not applicable, so test passes if pages mapped in RAM decrease after
> + * reclaiming memory with MADV_PAGEOUT and RAM doesn't contain
> + * reclaimed memory anymore.
> + */
> +
> +#define _GNU_SOURCE
> +
> +#include <sys/mman.h>
> +#include "tst_test.h"
> +#include "lapi/mmap.h"
> +#include "lapi/syscalls.h"
> +#include "cma.h"
> +
> +#define MEM_CHILD	(10 * 1024 * 1024)
> +
> +static char *filename = "file.bin";
> +static void **data_ptr;
> +
> +static void child_alloc(void)
> +{
> +	int fd;
> +	char *ptr;
> +	int freed = 1;
> +	struct addr_mapping map_before;
> +	struct addr_mapping map_after;
> +
> +	tst_res(TINFO, "Allocate file-backed memory");
> +
> +	fd = SAFE_OPEN(filename, O_CREAT | O_RDWR);
> +	SAFE_FTRUNCATE(fd, MEM_CHILD);
> +
> +	*data_ptr = SAFE_MMAP(NULL, MEM_CHILD,
> +			PROT_READ | PROT_WRITE,
> +			MAP_SHARED, fd, 0);
> +
> +	tst_res(TINFO, "Dirty memory");
> +	memset(*data_ptr, 'a', MEM_CHILD);
> +
> +	read_address_mapping((unsigned long)*data_ptr, &map_before);
> +
> +	TST_CHECKPOINT_WAKE_AND_WAIT(0);
> +
> +	for (ptr = *data_ptr; *ptr != '\0'; ptr++) {
> +		if (*ptr == 'a') {
> +			freed = 0;
> +			break;
> +		}
> +	}

This will loop once, or?

> +
> +	if (freed) {
> +		tst_res(TFAIL, "Memory has been freed");

We'll probably get a segfault or sigbus if its unmapped somehow. I guess
you could do a memcmp on the range to test that it didn't randomly
change though.

Otherwise this one looks good.

-- 
Thank you,
Richard.

-- 
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