Re: [LTP] [PATCH v1] mmapstress06: TCONF on systems without swap space

[Petr Vorel <pvorel@suse.cz>]

Hi all,

> Hi all,

> > mmapstress06 is designed to stress the mfile_swap kernel primitive, which
Uh, I overlooked "mfile_swap kernel primitive". Then the approach would make
sense, but is it really true? mfile_swap does not exist any more, not even in a
git log. Test was added in January 2003, e.g. even before 2.6.

> > manages shared anonymous memory. On architectures with large pages (like
> > 64KB on ppc64le), the test's hardcoded request for 32769 pages results
> > in a ~2GB mapping. So in suse test system configured with 2GB of RAM and
> > no swap space, the test will fails with following information:

I'm not really sure. if that's caused by missing swap or would it work on
machine with RAM big enough which has swap disabled (I guess you retest with
e.g. 8 GB RAM). Otherwise I'd prefer prefer to deal with errno ENOMEM (12)
instead (as I pointed out previously).

Kind regards,
Petr

> > mmapstress06: errno = 12; large mmap failed
> > for this test to run, it needs a mmap space of
> > 32769 pages

> > The failure occurs because the 2GB request cannot be fulfilled within
> > the 2GB RAM limit without swap backing. Since the test specifically
> > intends to exercise swap-related logic (mfile_swap), it should be skipped
> > with TCONF when the system lacks swap space.

> > Signed-off-by: Wei Gao <wegao@suse.com>
> > ---
> >  testcases/kernel/mem/mmapstress/mmapstress06.c | 8 ++++++++
...
> > +	if (tst_available_swap() <= 0) {
> > +		tst_resm(TCONF, "Test requires swap space to exercise mfile_swap logic");
> Why to require swap for the test instead of checking for ENOMEM later?

> > +		tst_exit();
> nit: I'd use tst_brkm() although it has ugly "Remaining cases broken" message as
> it will be more obvious when doing rewrite.

> > +	}

> How about this? (with cleanup of ugly printf).

> Kind regards,
> Petr

> +++ testcases/kernel/mem/mmapstress/mmapstress06.c
> @@ -89,10 +89,12 @@ int main(int argc, char *argv[])
>  	    (mmapaddr, (ANON_GRAN_PAGES_MAX * NMFPTEPG + 1) * pagesize,
>  	     PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_SHARED, 0,
>  	     0) == (caddr_t) - 1) {
> -		ERROR("large mmap failed");
> -		printf("for this test to run, it needs a mmap space of\n");
> -		printf("%d pages\n", (ANON_GRAN_PAGES_MAX * NMFPTEPG + 1));
> -		return 1;
> +		if (errno == ENOMEM) {
> +			tst_brkm(TCONF, NULL, "not enough memory or swap for mmap() %d pages",
> +					 ANON_GRAN_PAGES_MAX * NMFPTEPG + 1);
> +		}
> +
> +		tst_brkm(TBROK | TERRNO, NULL, "mmap() failed");
>  	}
>  	(void)sleep(sleep_time);
>  	(void)time(&t);

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