Re: [PATCH v2] mm/page_alloc: fix watchdog soft lockups during set_zone_contiguous()

[Michal Hocko]

On Fri 17-04-20 15:12:47, Andrew Morton wrote:
> On Thu, 16 Apr 2020 09:34:17 +0200 David Hildenbrand <david@xxxxxxxxxx> wrote:
> 
> > Without CONFIG_PREEMPT, it can happen that we get soft lockups detected,
> > e.g., while booting up.
> > 
> > ...
> > 
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -1607,6 +1607,7 @@ void set_zone_contiguous(struct zone *zone)
> >  		if (!__pageblock_pfn_to_page(block_start_pfn,
> >  					     block_end_pfn, zone))
> >  			return;
> > +		cond_resched();
> >  	}
> >  
> >  	/* We confirm that there is no hole */
> 
> I added cc:stable to this one.  Please let me know if that wasn't a
> good idea.

Really large memory setups tend to run on distribution kernels so
backporting to old kernels doesn't really harm.
-- 
Michal Hocko
SUSE Labs