Re: [PATCH v1] selftest mm/mseal: fix test_seal_mremap_move_dontunmap_anyaddr

[Pedro Falcato]

On Wed, Aug 7, 2024 at 7:03 PM Jeff Xu <jeffxu@xxxxxxxxxx> wrote:
<snip>
>
> test_seal_mremap_move_dontunmap use 0 as new_addr, 0 indicates
> allocating a new memory.
> test_seal_mremap_move_dontunmap_anyaddr uses any arbitrary address as
> a new address.

No, MREMAP_DONTUNMAP uses the address you pass as a hint, aka you're
just testing get_unmapped_area, not any mseal capability.
There's no forced moving here.

>
> > You also don't know if 0xdead0000 is a valid page (hexagon for
> > instance seems to support 256KiB and 1MiB pages, so does ppc32, and
> > this is not something that should be hardcoded).
> >
> usually hardcode value is not good practice, but the point of this
> test is to show
> mremap can really relocate the mapping to an arbitrary address.

That's what test_seal_mremap_move_dontunmap does, no?

>
> Do you have any suggestions here ? I can think of two options to choose from:
>
> 1> use 0xd0000000
> 2> allocate a memory then free it, reuse the ptr.

Personally I'd prefer 2, if you really want to keep the test. It's
also a strategy used elsewhere (e.g mremap_dontunmap.c).

FWIW I don't have the mental strength to bikeshed over this any more,
so please do what you think is best!

-- 
Pedro