Re: [PATCH v3 4/4] mm: prohibit NULL deference exposed for unsupported non-blockable __GFP_NOFAIL

[Michal Hocko <mhocko@suse.com>]

On Mon 19-08-24 11:44:39, David Hildenbrand wrote:
[...]
> >   	if (gfp_mask & __GFP_NOFAIL) {
> >   		/*
> > -		 * All existing users of the __GFP_NOFAIL are blockable, so warn
> > -		 * of any new users that actually require GFP_NOWAIT
> > +		 * All existing users of the __GFP_NOFAIL are blockable
> > +		 * otherwise we introduce a busy loop with inside the page
> > +		 * allocator from non-sleepable contexts
> >   		 */
> > -		if (WARN_ON_ONCE_GFP(!can_direct_reclaim, gfp_mask))
> > -			goto fail;
> > +		BUG_ON(!can_direct_reclaim);
> 
> No new BUG_ON(), WARN_ON_ONCE() is good enough for something that should be
> found during ordinary testing.

Do you mean 
	if (WARN_ON_ONCE_GFP(...))
		goto retry?

Barry has mentioned that option in the changelog. 
-- 
Michal Hocko
SUSE Labs