Re: [PATCH v3 7/8] selftests/mm: refactor uffd_poll_thread to allow custom fault handlers

Peter Xu
2023-07-07T21:01:55Z

On Fri, Jul 07, 2023 at 01:38:16PM -0700, Axel Rasmussen wrote:
> Ah, so I tried switching back to the {0} initializer, and was reminded
> why I didn't do that in v1. :) Ignoring the missing braces warning I
> talked about before, using {0} here is actually an error
> ("variable-sized object may not be initialized") because this is a
> variable sized array (nr_cpus isn't constant). So, that option is out.
>
> I'm not a huge fan of adding the free() cleanup and dealing with all
> of the err() calls this function has.

Oh, that's definitely not needed - as long as we know we're going to quit,
we let kernel clean everything is fine.

I just worry in the future there can be a loop of userfaultfd_stress() so
it can OOM a host even if no err() hit but by looping. I hope I explained
what I meant.. so it's still good we make sure things freed properly when
in success paths and when we're at it.

>
> Originally I switched to calloc() because I'm not a big fan of VLAs
> anyway. But, as a compromise in v4 I'll leave it a VLA, and switch to
> memset() for initializing it.

That'll be good enough to me. Thanks a lot,

--
Peter Xu