On Wed, Apr 14, 2021 at 07:09:15PM +0200, Oleg Nesterov wrote:
> On 04/13, Andrei Vagin wrote:
> >
> > +static void swap_mm(struct mm_struct *prev_mm, struct mm_struct *target_mm)
> > +{
> > + struct task_struct *tsk = current;
> > + struct mm_struct *active_mm;
> > +
> > + task_lock(tsk);
> > + /* Hold off tlb flush IPIs while switching mm's */
> > + local_irq_disable();
> > +
> > + sync_mm_rss(prev_mm);
> > +
> > + vmacache_flush(tsk);
> > +
> > + active_mm = tsk->active_mm;
> > + if (active_mm != target_mm) {
> > + mmgrab(target_mm);
> > + tsk->active_mm = target_mm;
> > + }
> > + tsk->mm = target_mm;
> > + switch_mm_irqs_off(active_mm, target_mm, tsk);
> > + local_irq_enable();
> > + task_unlock(tsk);
> > +#ifdef finish_arch_post_lock_switch
> > + finish_arch_post_lock_switch();
> > +#endif
> > +
> > + if (active_mm != target_mm)
> > + mmdrop(active_mm);
> > +}
>
> I think this should be unified with kthread_use_mm() somehow...
I agree.
>
> And does it really need the "prev_mm" argument? It must be tsk->mm, no?
No, it doesn't. It is leftover of unuse_mm. BTW why do we pass mm to kthread_unuse_mm?
Thanks,
Andrei.
