Re: [PATCH v5 16/18] x86/sgx: Limit process EPC usage with misc cgroup controller

[Haitao Huang]

On Tue, 17 Oct 2023 13:54:54 -0500, Michal Koutný <mkoutny@xxxxxxxx> wrote:

> On Fri, Sep 22, 2023 at 08:06:55PM -0700, Haitao Huang  
> <haitao.huang@xxxxxxxxxxxxxxx> wrote:
> > +static void sgx_epc_cgroup_free(struct misc_cg *cg)
> > +{
> > +	struct sgx_epc_cgroup *epc_cg;
> > +
> > +	epc_cg = sgx_epc_cgroup_from_misc_cg(cg);
>
> It should check for !epc_cg since the misc controller implementation
> in misc_cg_alloc() would roll back even on non-allocated resources.

Good catch. Will fix.

> > +	cancel_work_sync(&epc_cg->reclaim_work);
> > +	kfree(epc_cg);
> > +}
> > +
> > +static void sgx_epc_cgroup_max_write(struct misc_cg *cg)
> > +{
> > +	struct sgx_epc_reclaim_control rc;
> > +	struct sgx_epc_cgroup *epc_cg;
> > +
> > +	epc_cg = sgx_epc_cgroup_from_misc_cg(cg);
> > +
> > +	sgx_epc_reclaim_control_init(&rc, epc_cg);
> > +	/* Let the reclaimer to do the work so user is not blocked */
> > +	queue_work(sgx_epc_cg_wq, &rc.epc_cg->reclaim_work);
>
> This is weird. The writer will never learn about the result of the
> operation.
Right. With the new plan, this callback will be removed.

Thanks
Haitao