Re: [PATCH v5 12/13] zram: borrow idle decompression streams in exclusive mode

[Sergey Senozhatsky <senozhatsky@chromium.org>]

On (26/10/19 03:53), sashiko-bot@kernel.org wrote:
[..]
> > +static struct zcomp_dstrm *zcomp_dstrm_excl_tryget(struct zcomp *comp)
> > +{
> > +	struct zcomp_dstrm *zstrm;
> > +	unsigned int cpu;
> > +
> > +	/* Best-effort start CPU hint; migration during the scan is fine */
> > +	for_each_online_cpu_wrap(cpu, raw_smp_processor_id()) {
> > +		zstrm = per_cpu_ptr(comp->dstream, cpu);
> > +		if (zcomp_dstrm_excl_trylock(zstrm))
> > +			return zstrm;
> > +	}
> > +	return NULL;
> > +}
> 
> [Severity: High]
> Does passing raw_smp_processor_id() directly as the start argument to
> for_each_online_cpu_wrap() in zcomp_dstrm_excl_tryget() break the loop
> termination logic when the task migrates during the scan?

I guess you are right.  I'll fixup in v6.