On 05.02.20 14:34, Baoquan He wrote: > On 02/05/20 at 02:20pm, David Hildenbrand wrote: >> On 05.02.20 13:43, Baoquan He wrote: >>> On 02/04/20 at 03:42pm, David Hildenbrand wrote: >>>> On 04.02.20 15:25, Baoquan He wrote: >>>>> On 10/06/19 at 10:56am, David Hildenbrand wrote: >>>>>> If we have holes, the holes will automatically get detected and removed >>>>>> once we remove the next bigger/smaller section. The extra checks can >>>>>> go. >>>>>> >>>>>> Cc: Andrew Morton <[email protected]> >>>>>> Cc: Oscar Salvador <[email protected]> >>>>>> Cc: Michal Hocko <[email protected]> >>>>>> Cc: David Hildenbrand <[email protected]> >>>>>> Cc: Pavel Tatashin <[email protected]> >>>>>> Cc: Dan Williams <[email protected]> >>>>>> Cc: Wei Yang <[email protected]> >>>>>> Signed-off-by: David Hildenbrand <[email protected]> >>>>>> --- >>>>>> mm/memory_hotplug.c | 34 +++++++--------------------------- >>>>>> 1 file changed, 7 insertions(+), 27 deletions(-) >>>>>> >>>>>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c >>>>>> index f294918f7211..8dafa1ba8d9f 100644 >>>>>> --- a/mm/memory_hotplug.c >>>>>> +++ b/mm/memory_hotplug.c >>>>>> @@ -393,6 +393,9 @@ static void shrink_zone_span(struct zone *zone, >>>>>> unsigned long start_pfn, >>>>>> if (pfn) { >>>>>> zone->zone_start_pfn = pfn; >>>>>> zone->spanned_pages = zone_end_pfn - pfn; >>>>>> + } else { >>>>>> + zone->zone_start_pfn = 0; >>>>>> + zone->spanned_pages = 0; >>>>>> } >>>>>> } else if (zone_end_pfn == end_pfn) { >>>>>> /* >>>>>> @@ -405,34 +408,11 @@ static void shrink_zone_span(struct zone *zone, >>>>>> unsigned long start_pfn, >>>>>> start_pfn); >>>>>> if (pfn) >>>>>> zone->spanned_pages = pfn - zone_start_pfn + 1; >>>>>> + else { >>>>>> + zone->zone_start_pfn = 0; >>>>>> + zone->spanned_pages = 0; >>>>> >>>>> Thinking in which case (zone_start_pfn != start_pfn) and it comes here. >>>> >>>> Could only happen in case the zone_start_pfn would have been "out of the >>>> zone already". If you ask me: unlikely :) >>> >>> Yeah, I also think it's unlikely to come here. >>> >>> The 'if (zone_start_pfn == start_pfn)' checking also covers the case >>> (zone_start_pfn == start_pfn && zone_end_pfn == end_pfn). So this >>> zone_start_pfn/spanned_pages resetting can be removed to avoid >>> confusion. >> >> At least I would find it more confusing without it (or want a comment >> explaining why this does not have to be handled and why the !pfn case is >> not possible). > > I don't get why being w/o it will be more confusing, but it's OK since > it doesn't impact anything.
Because we could actually BUG_ON(!pfn) here, right? Only having a "if (pfn)" leaves the reader wondering "why is the other case not handled". > >> >> Anyhow, that patch is already upstream and I don't consider this high >> priority. Thanks :) > > Yeah, noticed you told Wei the status in another patch thread, I am fine > with it, just leave it to you to decide. Thanks. I am fairly busy right now. Can you send a patch (double-checking and making this eventually unconditional?). Thanks! -- Thanks, David / dhildenb
