On Wed 19-08-20 12:11:54, David Hildenbrand wrote: > We don't allow to offline memory with holes, all boot memory is online, > and all hotplugged memory cannot have holes. > > We can now simplify onlining of pages. As we only allow to online/offline > full sections and sections always span full MAX_ORDER_NR_PAGES, we can just > process MAX_ORDER - 1 pages without further special handling. > > The number of onlined pages simply corresponds to the number of pages we > were requested to online. > > While at it, refine the comment regarding the callback not exposing all > pages to the buddy. > > Cc: Andrew Morton <[email protected]> > Cc: Michal Hocko <[email protected]> > Cc: Wei Yang <[email protected]> > Cc: Baoquan He <[email protected]> > Cc: Pankaj Gupta <[email protected]> > Cc: Oscar Salvador <[email protected]> > Signed-off-by: David Hildenbrand <[email protected]>
Acked-by: Michal Hocko <[email protected]> > --- > mm/memory_hotplug.c | 38 ++++++++++---------------------------- > 1 file changed, 10 insertions(+), 28 deletions(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 0011a1115381c..3aba0d956f9b1 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -617,31 +617,22 @@ void generic_online_page(struct page *page, unsigned > int order) > } > EXPORT_SYMBOL_GPL(generic_online_page); > > -static int online_pages_range(unsigned long start_pfn, unsigned long > nr_pages, > - void *arg) > +static void online_pages_range(unsigned long start_pfn, unsigned long > nr_pages) > { > const unsigned long end_pfn = start_pfn + nr_pages; > unsigned long pfn; > - int order; > > /* > - * Online the pages. The callback might decide to keep some pages > - * PG_reserved (to add them to the buddy later), but we still account > - * them as being online/belonging to this zone ("present"). > + * Online the pages in MAX_ORDER - 1 aligned chunks. The callback might > + * decide to not expose all pages to the buddy (e.g., expose them > + * later). We account all pages as being online and belonging to this > + * zone ("present"). > */ > - for (pfn = start_pfn; pfn < end_pfn; pfn += 1ul << order) { > - order = min(MAX_ORDER - 1, get_order(PFN_PHYS(end_pfn - pfn))); > - /* __free_pages_core() wants pfns to be aligned to the order */ > - if (WARN_ON_ONCE(!IS_ALIGNED(pfn, 1ul << order))) > - order = 0; > - (*online_page_callback)(pfn_to_page(pfn), order); > - } > + for (pfn = start_pfn; pfn < end_pfn; pfn += MAX_ORDER_NR_PAGES) > + (*online_page_callback)(pfn_to_page(pfn), MAX_ORDER - 1); > > /* mark all involved sections as online */ > online_mem_sections(start_pfn, end_pfn); > - > - *(unsigned long *)arg += nr_pages; > - return 0; > } > > /* check which state of node_states will be changed when online memory */ > @@ -795,7 +786,6 @@ int __ref online_pages(unsigned long pfn, unsigned long > nr_pages, > int online_type, int nid) > { > unsigned long flags; > - unsigned long onlined_pages = 0; > struct zone *zone; > int need_zonelists_rebuild = 0; > int ret; > @@ -831,19 +821,11 @@ int __ref online_pages(unsigned long pfn, unsigned long > nr_pages, > setup_zone_pageset(zone); > } > > - ret = walk_system_ram_range(pfn, nr_pages, &onlined_pages, > - online_pages_range); > - if (ret) { > - /* not a single memory resource was applicable */ > - if (need_zonelists_rebuild) > - zone_pcp_reset(zone); > - goto failed_addition; > - } > - > - zone->present_pages += onlined_pages; > + online_pages_range(pfn, nr_pages); > + zone->present_pages += nr_pages; > > pgdat_resize_lock(zone->zone_pgdat, &flags); > - zone->zone_pgdat->node_present_pages += onlined_pages; > + zone->zone_pgdat->node_present_pages += nr_pages; > pgdat_resize_unlock(zone->zone_pgdat, &flags); > > /* > -- > 2.26.2 > -- Michal Hocko SUSE Labs
