netdev - Re: [PATCH bpf-next] selftests/xsk: fix munmap for hugepage allocated umem

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Message-ID: <CAHApi-=NkvNvbDJTwLcPfo_ZkRg9vfVNmQN50_LzA3K8t7Q4JQ@mail.gmail.com>
Date:   Thu, 20 Apr 2023 12:09:56 +0200
From:   Kal Cutter Conley <kal.conley@...tris.com>
To:     Magnus Karlsson <magnus.karlsson@...il.com>
Cc:     magnus.karlsson@...el.com, bjorn@...nel.org, ast@...nel.org,
        daniel@...earbox.net, netdev@...r.kernel.org,
        maciej.fijalkowski@...el.com, tirthendu.sarkar@...el.com,
        bpf@...r.kernel.org
Subject: Re: [PATCH bpf-next] selftests/xsk: fix munmap for hugepage allocated umem

> It was a conscious decision to require a hugepage size of 2M. I want
> it to fail if you do not have it since the rest of the code will not
> work if you are using some other size. Yes, it is possible to discover
> what hugepage sizes exist and act on that, but I want to keep the code
> simple.

Yes. I understood that and I think the solution is reasonable. Sadly,
it's not trivial to query the default hugepage size from userspace
AFAIK. Is parsing /proc/meminfo the only way?

What I meant was: "the tests may still fail _with the old mode of
failure (out of memory)_ if the default hugepage size is > 2MB".