Re: [PATCH for-7.5 5/5] memcg: simplify high limit handling after a charge

[Michal Hocko]

On Wed 14-10-26 10:43:33, Shakeel Butt wrote:
> On Wed, Oct 14, 2026 at 01:46:23PM +0200, Michal Hocko wrote:
> > On Sat 10-10-26 14:09:57, Shakeel Butt wrote:
> > [...]
> > > -	/* Interrupts, kernel threads, and remote chargers stop here. */
> > > -	if (use_worker)
> > > +	/*
> > > +	 * Use a worker for interrupts, kernel threads, and tasks whose mm
> > > +	 * does not match the charged hierarchy.
> > > +	 */
> > > +	if (use_high_work) {
> > > +		if (!iter)
> > > +			return;
> > > +		if (allow_spinning)
> > > +			schedule_work(&iter->high_work);
> > > +		else
> > > +			irq_work_queue(&iter->high_irq_work);
> > >  		return;
> > > +	}
> > > +
> > > +	if (iter) {
> > 
> > Would it be much simpler to bail out on iter==NULL (i.e. nothing over
> > high limit) right after the loop?
> > 
> 
> I want this patch to not change any behavior. If we return here when iter is
> NULL, we will skip a potential call to __mem_cgroup_handle_over_high() when
> current->memcg_nr_pages_over_high > MEMCG_CHARGE_BATCH. Though I agree that is
> very subtle and most probably unexpected. If we decide to remove it, we should
> do it in a separate patch.

OK, makes sense.

Acked-by: Michal Hocko <mhocko@xxxxxxxx>
-- 
Michal Hocko
SUSE Labs