Re: [PATCH 0/2 v8] oom: capture unreclaimable slab info in oom message

[Yang Shi]

On 10/2/17 4:20 AM, Michal Hocko wrote:
> On Thu 28-09-17 13:36:57, Tetsuo Handa wrote:
> > On 2017/09/28 6:46, Yang Shi wrote:
> > > Changelog v7 â> v8:
> > > * Adopted Michalâs suggestion to dump unreclaim slab info when unreclaimable slabs amount > total user memory. Not only in oom panic path.
> >
> > Holding slab_mutex inside dump_unreclaimable_slab() was refrained since V2
> > because there are
> >
> > 	mutex_lock(&slab_mutex);
> > 	kmalloc(GFP_KERNEL);
> > 	mutex_unlock(&slab_mutex);
> >
> > users. If we call dump_unreclaimable_slab() for non OOM panic path, aren't we
> > introducing a risk of crash (i.e. kernel panic) for regular OOM path?
>
> yes we are
>   
> > We can try mutex_trylock() from dump_unreclaimable_slab() at best.
> > But it is still remaining unsafe, isn't it?
>
> using the trylock sounds like a reasonable compromise.

OK, it sounds we reach agreement on trylock. Will solve those comments 
in v9.

Thanks,
Yang

>