On Thu 10-03-16 15:50:15, Johannes Weiner wrote: > uncharge_list() does an unusual list walk because the function can > take regular lists with dedicated list_heads as well as singleton > lists where a single page is passed via the page->lru list node. > > This can sometimes lead to confusion as well as suggestions to replace > the loop with a list_for_each_entry(), which wouldn't work.
Yes this confused at least me 2 times AFAIR. > > Signed-off-by: Johannes Weiner <[email protected]> Acked-by: Michal Hocko <[email protected]> Thanks! > --- > mm/memcontrol.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 8614e0d750e5..fa7bf354ae32 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -5420,6 +5420,10 @@ static void uncharge_list(struct list_head *page_list) > struct list_head *next; > struct page *page; > > + /* > + * Note that the list can be a single page->lru; hence the > + * do-while loop instead of a simple list_for_each_entry(). > + */ > next = page_list->next; > do { > unsigned int nr_pages = 1; > -- > 2.7.2 -- Michal Hocko SUSE Labs
