Re: [PATCH v2 1/3] mm: memory-failure: update ttu flag inside unmap_poisoned_folio

[David Hildenbrand <david@xxxxxxxxxx>]

> >   	if (folio_test_hugetlb(folio) && !folio_test_anon(folio)) {
> >   		struct address_space *mapping;
> >   
> > @@ -1572,7 +1598,7 @@ void unmap_poisoned_folio(struct folio *folio, enum ttu_flags ttu)
> >   		if (!mapping) {
> >   			pr_info("%#lx: could not lock mapping for mapped hugetlb folio\n",
> >   				folio_pfn(folio));
> > -			return;
> > +			return -EBUSY;
> >   		}
> >   
> >   		try_to_unmap(folio, ttu|TTU_RMAP_LOCKED);
> > @@ -1580,6 +1606,8 @@ void unmap_poisoned_folio(struct folio *folio, enum ttu_flags ttu)
> >   	} else {
> >   		try_to_unmap(folio, ttu);
> >   	}
> > +
> > +	return folio_mapped(folio) ? -EBUSY : 0;
>
> Do we really need this return value? It's unused in do_migrate_range().

I suggested it, because the folio_mapped() is nowadays extremely cheap. 
It cleans up hwpoison_user_mappings() quite nicely.

Any particular reason we shouldn't be doing that?

--
Cheers,

David / dhildenb