Re: [PATCH bpf-next v3 3/6] selftests/vm: extend test_vmalloc to test execmem_* APIs

[Song Liu <song@kernel.org>]

On Wed, Nov 16, 2022 at 5:49 PM Luis Chamberlain <mcgrof@kernel.org> wrote:
>
> On Wed, Nov 16, 2022 at 05:06:18PM -0800, Song Liu wrote:
> > Add logic to test execmem_[alloc|fill|free] in test_vmalloc.c.
> > No need to change tools/testing/selftests/vm/test_vmalloc.sh.
> >
> > Signed-off-by: Song Liu <song@kernel.org>
> > ---
> >  lib/test_vmalloc.c | 30 ++++++++++++++++++++++++++++++
> >  1 file changed, 30 insertions(+)
> >
> > diff --git a/lib/test_vmalloc.c b/lib/test_vmalloc.c
> > index cf7780572f5b..6591c4932c3c 100644
> > --- a/lib/test_vmalloc.c
> > +++ b/lib/test_vmalloc.c
> > @@ -50,6 +50,7 @@ __param(int, run_test_mask, INT_MAX,
> >               "\t\tid: 128,  name: pcpu_alloc_test\n"
> >               "\t\tid: 256,  name: kvfree_rcu_1_arg_vmalloc_test\n"
> >               "\t\tid: 512,  name: kvfree_rcu_2_arg_vmalloc_test\n"
> > +             "\t\tid: 1024, name: execmem_alloc_test\n"
> >               /* Add a new test case description here. */
> >  );
> >
> > @@ -352,6 +353,34 @@ kvfree_rcu_2_arg_vmalloc_test(void)
> >       return 0;
> >  }
> >
> > +static int
> > +execmem_alloc_test(void)
> > +{
> > +     void *p, *tmp;
> > +     int i;
> > +
> > +     for (i = 0; i < test_loop_count; i++) {
> > +             /* allocate variable size, up to 64kB */
> > +             size_t size = (i % 1024 + 1) * 64;
> > +
> > +             p = execmem_alloc(size, 64);
> > +             if (!p)
> > +                     return -1;
> > +
> > +             tmp = execmem_fill(p, "a", 1);
> > +             if (tmp != p)
> > +                     return -1;
> > +
> > +             tmp = execmem_fill(p + size - 1, "b", 1);
> > +             if (tmp != p + size - 1)
> > +                     return -1;
> > +
> > +             execmem_free(p);
> > +     }
> > +
> > +     return 0;
> > +}
> > +
>
> This is a basic test and it is useful.
>
> But given all those WARN_ON() and WARN_ON_ONCE() I think the real value
> test here would be to race 1000 threads doing this at the same time.

test_vmalloc supports parallel tests. We can do something like

  tools/testing/selftests/vm/test_vmalloc.sh nr_threads=XXX run_test_mask=1024

Thanks,
Song