On Wed 07-04-21 10:27:49, Oscar Salvador wrote:
> On Mon, Apr 05, 2021 at 04:00:40PM -0700, Mike Kravetz wrote:
[...]
> > @@ -2671,22 +2682,34 @@ static void try_to_free_low(struct hstate *h,
> > unsigned long count,
> > nodemask_t *nodes_allowed)
> > {
> > int i;
> > + struct page *page, *next;
> > + LIST_HEAD(page_list);
> >
> > if (hstate_is_gigantic(h))
> > return;
> >
> > + /*
> > + * Collect pages to be freed on a list, and free after dropping lock
> > + */
> > for_each_node_mask(i, *nodes_allowed) {
> > - struct page *page, *next;
> > struct list_head *freel = &h->hugepage_freelists[i];
> > list_for_each_entry_safe(page, next, freel, lru) {
> > if (count >= h->nr_huge_pages)
> > - return;
> > + goto out;
> > if (PageHighMem(page))
> > continue;
> > remove_hugetlb_page(h, page, false);
> > - update_and_free_page(h, page);
> > + list_add(&page->lru, &page_list);
> > }
> > }
> > +
> > +out:
> > + spin_unlock(&hugetlb_lock);
> > + list_for_each_entry_safe(page, next, &page_list, lru) {
> > + update_and_free_page(h, page);
> > + cond_resched();
> > + }
> > + spin_lock(&hugetlb_lock);
>
> Can we get here with an empty list?
An emoty page_list? If yes then sure, this can happen but
list_for_each_entry_safe will simply not iterate. Or what do you mean?
--
Michal Hocko
SUSE Labs
