Re: [PATCH 2/2] selftests/mm: Add a new test for madv and hugetlb

[Breno Leitao <leitao@debian.org>]

On Wed, Oct 04, 2023 at 08:22:08PM -0400, Rik van Riel wrote:
> On Wed, 2023-10-04 at 10:11 -0700, Breno Leitao wrote:
> > 
> > +char *huge_ptr;
> > +
> > +/* Touch the memory while it is being madvised() */
> > +void *touch(void *unused)
> > +{
> > +       char *ptr = (char *)huge_ptr;
> > +
> > +       if (!ptr) {
> > +               fprintf(stderr, "Failed to allocate memory\n");
> > +               perror("");
> > +       }
> 
> I'm not sure this error message makes a lot of sense
> away from where the huge page gets allocated.

Right. I think I don't need this whole "if" clause at all. Let me remove
it.

> > 
> > +       while (max--) {
> > +               huge_ptr = mmap(NULL, MMAP_SIZE, PROT_READ |
> > PROT_WRITE,
> > +                               MAP_PRIVATE | MAP_ANONYMOUS |
> > MAP_HUGETLB, -1, 0);
> > +
> > +               if ((unsigned long)huge_ptr == -1) {
> > +                       perror("Failed to allocate\n");
> > +                       continue;
> > +               }
> 
> Should the test case just exit with an error here, when
> the allocation fails?

Yes, probably skip the test if we are not able to allocate the memory.
I just found I can use something as `ksft_exit_skip()` for this purpose.

Thanks for the great feedbacks!