Re: [PATCH v17 18/23] platform/x86: Intel SGX driver

[Jarkko Sakkinen]

On Mon, Dec 17, 2018 at 10:36:13AM -0800, Sean Christopherson wrote:
> I'm pretty sure doing mmget() would result in circular dependencies and
> a zombie enclave.  In the do_exit() case where a task is abruptly killed:
>  
>   - __mmput() is never called because the enclave holds a ref
>   - sgx_encl_release() is never be called because its VMAs hold refs
>   - sgx_vma_close() is never called because __mmput()->exit_mmap() is
>     blocked and the process itself is dead, i.e. won't unmap anything.

Right, it does, you are absolutely right. Tried it and removed the
commit already.

Well, what we came up from your suggestion i.e. setting mm to NULL
and checking that is very subtle change and does not have any such
circular dependencies. We'll go with that.

/Jarkko