Re: [PATCH v5 12/18] x86/sgx: Add EPC OOM path to forcefully reclaim EPC

[Dave Hansen]

On 10/18/23 08:26, Haitao Huang wrote:
> Maybe not in sense of killing something. My understanding memory.reclaim
> does not necessarily invoke the OOM killer. But what I really intend to
> say is we can have a separate knob for user to express the need for
> reducing the current usage explicitly and keep "misc.max' non-preemptive
> semantics intact. When we implement that new knob, then we can define
> what kind of reclaim for that. Depending on vEPC implementation, it may
> or may not involve killing VMs. But at least that semantics will be
> explicit for user.

I'm really worried that you're going for "perfect" semantics here.  This
is SGX.  It's *NOT* getting heavy use and even fewer folks will ever
apply cgroup controls to it.

Can we please stick to simple, easily-coded rules here?  I honestly
don't think these corner cases matter all that much and there's been
*WAY* too much traffic in this thread for what is ultimately not that
complicated.  Focus on *ONE* thing:

1. Admin sets a limit
2. Enclave is created
3. Enclave hits limit, allocation fails

Nothing else matters.  What if the admin lowers the limit on an
already-created enclave?  Nobody cares.  Seriously.  What about inducing
reclaim?  Nobody cares.  What about vEPC?  Doesn't matter, an enclave
page is an enclave page.