[LTP] memcg/functional: fix memcg_failcnt intermittent timeout by disabling swap

[Li Wang]

linuxtestproject.agent@gmail.com wrote:

> Hi Xuewen,
> 
> On Fri, Aug 7, 2026, Xuewen Wang wrote:
> > memcg/functional: fix memcg_failcnt intermittent timeout by disabling swap
> 
> > +do_setup()
> > +{
> > +	memcg_setup
> > +	swapoff -a
> > +}
> 
> Could this use ROD so a failed swapoff aborts the test? swapoff can fail
> when there is not enough memory to page the swap contents back in.
> _tst_run_iterations() ignores the setup function's return status, so the
> test proceeds with swap enabled and the original intermittent timeout
> remains.

Fair point that ignoring the return status defeats the purpose. But I'd
rather not TBROK on a swapoff failure, that's an environment limitation,
not a test failure. Especially swapoff here is an enhancement but not
a hard requirement for this test.

> 
> > +do_cleanup()
> > +{
> > +	swapon -a
> > +	memcg_cleanup
> > +}
> 
> Could cleanup restore only swap areas that were active before setup, and
> only if swapoff was attempted? TST_DO_CLEANUP is set before do_setup(), so
> a TCONF from memcg_setup() reaches this function before swapoff. swapon -a
> can then activate previously inactive fstab entries. Conversely, dynamically
> managed swap areas absent from fstab are disabled by swapoff -a but are not
> restored by swapon -a.

That is a bit over-engineering.

If an inactive fstab entry gets activated by swapon -a, that arguably
points to a misconfigured test host rather than something this test
should work around.


-- 
Regards,
Li Wang