On Wed, Jul 5, 2023 at 4:36 PM Mike Kravetz <mike.kravetz@xxxxxxxxxx> wrote:
>
> On 06/23/23 16:40, Jiaqi Yan wrote:
> > Traversal on llist (e.g. llist_for_each_safe) is only safe AFTER entries
> > are deleted from the llist.
> >
> > llist_del_all are lock free with itself. folio_clear_hugetlb_hwpoison()s
> > from __update_and_free_hugetlb_folio and memory_failure won't need
> > explicit locking when freeing the raw_hwp_list.
> >
> > Signed-off-by: Jiaqi Yan <jiaqiyan@xxxxxxxxxx>
> > ---
> > mm/memory-failure.c | 8 +++-----
> > 1 file changed, 3 insertions(+), 5 deletions(-)
>
> After updating the reason for patch in commit message as suggested by Naoya,
Thank you both Mike and Naoya! I will add the explanation in the next version.
>
> Acked-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
>
> --
> Mike Kravetz
>
> >
> > diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> > index 004a02f44271..c415c3c462a3 100644
> > --- a/mm/memory-failure.c
> > +++ b/mm/memory-failure.c
> > @@ -1825,12 +1825,11 @@ static inline struct llist_head *raw_hwp_list_head(struct folio *folio)
> >
> > static unsigned long __folio_free_raw_hwp(struct folio *folio, bool move_flag)
> > {
> > - struct llist_head *head;
> > - struct llist_node *t, *tnode;
> > + struct llist_node *t, *tnode, *head;
> > unsigned long count = 0;
> >
> > - head = raw_hwp_list_head(folio);
> > - llist_for_each_safe(tnode, t, head->first) {
> > + head = llist_del_all(raw_hwp_list_head(folio));
> > + llist_for_each_safe(tnode, t, head) {
> > struct raw_hwp_page *p = container_of(tnode, struct raw_hwp_page, node);
> >
> > if (move_flag)
> > @@ -1840,7 +1839,6 @@ static unsigned long __folio_free_raw_hwp(struct folio *folio, bool move_flag)
> > kfree(p);
> > count++;
> > }
> > - llist_del_all(head);
> > return count;
> > }
> >
> > --
> > 2.41.0.162.gfafddb0af9-goog
> >
