On Tue, Aug 18, 2020 at 09:23:12AM +0200, David Hildenbrand wrote: >On 18.08.20 05:05, Wei Yang wrote: >> On Mon, Aug 17, 2020 at 07:07:04PM +0200, David Hildenbrand wrote: >>> On 17.08.20 18:05, Alexander Duyck wrote: >>>> >>>> >>>> On 8/17/2020 2:35 AM, David Hildenbrand wrote: >>>>> On 17.08.20 10:48, Wei Yang wrote: >>>>>> If "page" is the list head, list_for_each_entry_safe() would stop >>>>>> iteration. >>>>>> >>>>>> Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx> >>>>>> --- >>>>>> mm/page_reporting.c | 2 +- >>>>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>>>> >>>>>> diff --git a/mm/page_reporting.c b/mm/page_reporting.c >>>>>> index 3bbd471cfc81..aaaa3605123d 100644 >>>>>> --- a/mm/page_reporting.c >>>>>> +++ b/mm/page_reporting.c >>>>>> @@ -178,7 +178,7 @@ page_reporting_cycle(struct page_reporting_dev_info *prdev, struct zone *zone, >>>>>> * the new head of the free list before we release the >>>>>> * zone lock. >>>>>> */ >>>>>> - if (&page->lru != list && !list_is_first(&page->lru, list)) >>>>>> + if (!list_is_first(&page->lru, list)) >>>>>> list_rotate_to_front(&page->lru, list); >>>>>> >>>>>> /* release lock before waiting on report processing */ >>>>>> >>>>> >>>>> Is this a fix or a cleanup? If it's a fix, can this be reproduced easily >>>>> and what ere the effects? >>>>> >>>> >>>> This should be a clean-up. Since the &page->lru != list will always be true. >>>> >>> >>> Makes sense, maybe we can make that a little bit clearer in the patch >>> description. >>> >> >> Ok, do you have some suggestion on the description? >> >> A clean-up for commit xxx? >> >> I would appreciate your suggestion :-) >> > >I'd go with something like > >" >mm/page_reporting: drop stale list head check in page_reporting_cycle > >list_for_each_entry_safe() guarantees that we will never stumble over >the list head; "&page->lru != list" will always evaluate to true. Let's >simplify. >" > Looks really better than mine. Thanks a lot. >to stress that this is a pure simplifcation. > >Reviewed-by: David Hildenbrand <david@xxxxxxxxxx> > >>>> If I recall at some point the that was a check for &next->lru != list >>>> but I think I pulled out an additional conditional check somewhere so >>>> that we just go through the start of the loop again and iterate over >>>> reported pages until we are guaranteed to have a non-reported page to >>>> rotate to the top of the list with the general idea being that we wanted >>>> the allocator to pull non-reported pages before reported pages. >>> >>> -- >>> Thanks, >>> >>> David / dhildenb >> > > >-- >Thanks, > >David / dhildenb -- Wei Yang Help you, Help me
