[LTP] mmapstress06: Convert to new API

[linuxtestproject.agent@gmail.com]

Hi Wei,

On Fri, 05 Jun 2026, Wei Gao wrote:
> mmapstress06: Convert to new API

> +/*\
> + * Test ``:manpage:`mmap(2)``` with swap behavior.

The RST role is malformed. Other tests in the tree use it without
the surrounding double-backticks, e.g.:

  * Test :manpage:`mmap(2)` with swap behavior.

> +#include "tst_test.h"
> +#include "tst_safe_macros.h"

tst_test.h already includes tst_safe_macros.h; the second include
is redundant.

> +	if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)

WIFEXITED() and WEXITSTATUS() require <sys/wait.h>. That header is
not included, and nothing in the include chain pulls it in. Every
other test in testcases/kernel/mem/ that uses these macros includes
<sys/wait.h> explicitly (ksm05.c, vma01.c, mmapstress09.c).

> +	sysinfo(&s);
> +	total_swap = (unsigned long long)s.totalswap * s.mem_unit;
> +
> +	if (total_swap < map_size) {

This checks total (configured) swap, not available (free) swap. On a
system with 1 GB of total swap where 800 MB is already in use, the
check passes but the test would fail at runtime when only 200 MB of
free swap remains.

The tst_test framework provides .min_swap_avail (in megabytes) in
struct tst_test to guard against this; that field also removes the
need for the hand-rolled sysinfo() block. The swap check should also
test against the amount actually needed (map_size - mem_limit, around
500 MB), not against map_size (1000 MB).

The commit message also says "forcing the kernel to swap out exactly
500MB of memory", but the test only checks that cg_swap_after is
larger than cg_swap_before -- any non-zero increase would pass. The
word "exactly" is inaccurate.

Verdict: Needs revision

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