Re: [PATCH 2/4] mm/vmalloc: add support for __GFP_NOFAIL

[NeilBrown]

On Tue, 26 Oct 2021, Michal Hocko wrote:
> On Tue 26-10-21 09:59:36, Neil Brown wrote:
> > On Tue, 26 Oct 2021, Michal Hocko wrote:
> [...]
> > > @@ -3032,6 +3036,10 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
> > >  		warn_alloc(gfp_mask, NULL,
> > >  			"vmalloc error: size %lu, vm_struct allocation failed",
> > >  			real_size);
> > > +		if (gfp_mask & __GFP_NOFAIL) {
> > > +			schedule_timeout_uninterruptible(1);
> > > +			goto again;
> > > +		}
> > 
> > Shouldn't the retry happen *before* the warning?
> 
> I've done it after to catch the "depleted or fragmented" vmalloc space.
> This is not related to the memory available and therefore it won't be
> handled by the oom killer. The error message shouldn't imply the vmalloc
> allocation failure IMHO but I am open to suggestions.

The word "failed" does seem to imply what you don't want it to imply...

I guess it is reasonable to have this warning, but maybe add " -- retrying"
if __GFP_NOFAIL.

Thanks,
NeilBrown