[LTP] [PATCH 1/1] lib: Skip tst_{disable, enable}_oom_protection() for non-root

[Li Wang]

Hi Xu, Petr,

On Wed, Dec 22, 2021 at 10:26 AM xuyang2018.jy@fujitsu.com <
xuyang2018.jy@fujitsu.com> wrote:

> Hi Petr
> > If needed to set value also for non-root, use set_oom_score_adj().
> If so, why not rename set_oom_score_adj to tst_set_oom_score_adj and add
> declartion to tst_memutils.h?
>

Yes, it makes sense to expose this function to users to cover
more oom test scenarios. For instance, set a high (>0) or low (<0)
score in child_alloc() to verify if OOM-Killer still works well.
But so far, we don't have such tests.


> ps: also have a word typo in set_oom_score_adj, adjustement => adjustment.
>
> Best Regards
> Yang Xu
> >
> > Fixes: 8a0827766d ("lib: add functions to adjust oom score")
> >
> > Signed-off-by: Petr Vorel<pvorel@suse.cz>
> > ---
> >   include/tst_memutils.h | 11 ++++++++++-
> >   lib/tst_memutils.c     |  6 ++++++
> >   2 files changed, 16 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/tst_memutils.h b/include/tst_memutils.h
> > index 68a6e37714..e6f946ac0c 100644
> > --- a/include/tst_memutils.h
> > +++ b/include/tst_memutils.h
> > @@ -30,11 +30,15 @@ long long tst_available_mem(void);
> >    *   echo -1000>/proc/$PID/oom_score_adj
> >    * If the pid is 0 which means it will set on current(self) process.
> >    *
> > + * WARNING:
> > + *  Do nothing for non-root, because setting value<  0 requires root.
> > +    If you want to set value also for non-root, use set_oom_score_adj().
> > + *
> >    * Note:
> >    *  This exported tst_enable_oom_protection function can be used at
> anywhere
> >    *  you want to protect, but please remember that if you do enable
> protection
> >    *  on a process($PID) that all the children will inherit its score
> and be
> > - *  ignored by OOM Killer as well. So that's why
> tst_disable_oom_protection
> > + *  ignored by OOM Killer as well. So that's why
> tst_disable_oom_protection()
> >    *  to be used in combination.
> >    */
> >   void tst_enable_oom_protection(pid_t pid);
> > @@ -42,6 +46,11 @@ void tst_enable_oom_protection(pid_t pid);
> >   /*
> >    * Disable the OOM protection for the process($PID).
> >    *   echo 0>/proc/$PID/oom_score_adj
> > + *
> > + * WARNING:
> > + *  Do nothing for non-root, because it's expected to be cleanup after
> > + *  tst_enable_oom_protection(). Use set_oom_score_adj(), if you want
> to set
> > + *  value also for non-root.
> >    */
> >   void tst_disable_oom_protection(pid_t pid);
> >
> > diff --git a/lib/tst_memutils.c b/lib/tst_memutils.c
> > index 4346508d9a..f0695e026a 100644
> > --- a/lib/tst_memutils.c
> > +++ b/lib/tst_memutils.c
> > @@ -126,10 +126,16 @@ static void set_oom_score_adj(pid_t pid, int value)
> >
> >   void tst_enable_oom_protection(pid_t pid)
> >   {
> > +     if (geteuid() != 0)
>

This is not working as expected in Github CI. I'm still looking at the
problem.
https://github.com/wangli5665/ltp/runs/4602025797?check_suite_focus=true

And the worth mentioning, maybe better to do this check
in set_oom_score_adj() if we do not decide to expose
that function to user.

-- 
Regards,
Li Wang
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