Re: [PATCH v28 16/22] x86/sgx: Add a page reclaimer

[Jarkko Sakkinen]

On Thu, Mar 12, 2020 at 11:38:24AM -0700, Sean Christopherson wrote:
> On Fri, Mar 06, 2020 at 08:47:02PM +0200, Jarkko Sakkinen wrote:
> > On Thu, Mar 05, 2020 at 11:03:54AM -0800, Sean Christopherson wrote:
> > > We've also discussed taking a file descriptor to hold the backing, but
> > > unless I'm misreading the pagecache code, that doesn't solve the incorrect
> > > accounting problem because the current task, i.e. evicting task, would be
> > > charged.  In other words, whether the backing is kernel or user controlled
> > > is purely an ABI question.
> > 
> > Even if the file is owned by a different process the account happens
> > to "current"?
> 
> Yes.  Which makes sense as files do not have a 1:1 association with tasks.

Yeah, that makes sense. Looking at mm/memory.c.

Looking at finish_fault/alloc_set_pte/inc_mm_counter_fast code path that
is also what happens.

/Jarkko