[LTP] [PATCH v2] move_pages12: Make sure hugepages are available

[Cyril Hrubis]

Hi!
> > > I'm sporadically running into SIGBUS in this testcase, not sure if it's
> > > because of low memory or something else. Do you see it too?
> > 
> > None so far, but I haven't been running the test on anything else than
> > machines with just two numa nodes so far.
> > 
> > > I wonder if we should replace memset with MAP_POPULATE.
> > 
> > Isn't MAP_POPULATE best effort only?
> 
> It's a readahead for file mappings, not sure about anonymous.

See:

http://www.serverphorums.com/read.php?12,1204538,1204539#msg-1204539

As far as I remember the discussion MAP_POPULATE does not work in low
memory condition and mmap() returns without any error.

> As alternative commit [1] gave me idea to try mlock, and that seems
> to work too. If a node doesn't have enough memory I get ENOMEM.
> 
> diff --git a/testcases/kernel/syscalls/move_pages/move_pages12.c b/testcases/kernel/syscalls/move_pages/move_pages12.c
> index e1d956dba67e..4c7d5c2c01b0 100644
> --- a/testcases/kernel/syscalls/move_pages/move_pages12.c
> +++ b/testcases/kernel/syscalls/move_pages/move_pages12.c
> @@ -165,9 +165,15 @@ static void alloc_free_huge_on_node(unsigned int node, size_t size)
>                 tst_brk(TBROK | TERRNO, "mbind() failed");
>         }
>  
> -       numa_bitmask_free(bm);
> +       TEST(mlock(mem, size));
> +       if (TEST_RETURN) {
> +               SAFE_MUNMAP(mem, size);
> +               if (TEST_ERRNO == ENOMEM || TEST_ERRNO == EAGAIN)
> +                       tst_brk(TCONF, "Cannot lock huge pages");
> +               tst_brk(TBROK | TTERRNO, "mlock failed");
> +       }
>  
> -       memset(mem, 0, size);
> +       numa_bitmask_free(bm);
>  
>         SAFE_MUNMAP(mem, size);
>  }

LGTM.

-- 
Cyril Hrubis
chrubis@suse.cz