[LTP] [PATCH] lib/mem.c: handle the case oom0{3, 5} exit with EAGAIN situation

[Li Wang]

Hi,

On Wed, Sep 16, 2015 at 5:31 PM, Jan Stancek <jstancek@redhat.com> wrote:

>
>
>
>
> ----- Original Message -----
> > From: "Li Wang" <liwang@redhat.com>
> > To: "Jan Stancek" <jstancek@redhat.com>
> > Cc: ltp@lists.linux.it
> > Sent: Wednesday, 16 September, 2015 10:02:42 AM
> > Subject: Re: [PATCH] lib/mem.c: handle the case oom0{3,5} exit with
> EAGAIN situation
> > > Isn't this going to introduce infinite loop? Shouldn't we limit
> > > the number of retries by some finite number before we let it
> > > touch the pages (and hit OOM)?
> > >
> >
> > Hmm, at first I'm trying to use finite loop for the mlock(), but think
> > over, I feel it is not a big matter since  mlock() desen't need so much
> > memory to do the lock. and I did that.
> >
> > Anyway, for security consideration, finite loop is also has itself
> > advantages.
> >
> > If so, How about this:
>
> I think that's fine, I'd suggest we add some small usleep in the loop
> too (e.g. 250ms-500ms) to give it a moment before we give up on mlock().
>

Good. I will post v2.   Thank you for reviewing.


>
> Regards,
> Jan
>
> >
> > diff --git a/testcases/kernel/mem/lib/mem.c
> b/testcases/kernel/mem/lib/mem.c
> > index 8fe4bf0..99eeb04 100644
> > --- a/testcases/kernel/mem/lib/mem.c
> > +++ b/testcases/kernel/mem/lib/mem.c
> > @@ -30,6 +30,7 @@ static int alloc_mem(long int length, int testcase)
> >  {
> >         char *s;
> >         long i, pagesz = getpagesize();
> > +       int ln = 10;
> >
> >         tst_resm(TINFO, "thread (%lx), allocating %ld bytes.",
> >                 (unsigned long) pthread_self(), length);
> > @@ -39,8 +40,14 @@ static int alloc_mem(long int length, int testcase)
> >         if (s == MAP_FAILED)
> >                 return errno;
> >
> > -       if (testcase == MLOCK && mlock(s, length) == -1)
> > -               return errno;
> > +       if (testcase == MLOCK) {
> > +               while (mlock(s, length) == -1 && ln > 0) {
> > +                       if (EAGAIN != errno)
> > +                               return errno;
> > +                       ln--;
> > +               }
> > +       }
> >
> >
> >
> >
> > >
> > > Regards,
> > > Jan
> > >
> > > >  #ifdef HAVE_MADV_MERGEABLE
> > > >       if (testcase == KSM && madvise(s, length, MADV_MERGEABLE) ==
> -1)
> > > >               return errno;
> > > > --
> > > > 1.8.3.1
> > > >
> > > >
> > >
> >
> >
> >
> > --
> > Regards,
> > Li Wang
> > Email: liwang@redhat.com
> >
>



-- 
Regards,
Li Wang
Email: liwang@redhat.com
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