Initialize all pages reserved is an ancient behavior. Since commit 92923ca3aace ("mm: meminit: only set page reserved in the memblock region"), SetPageReserved is removed from __init_single_page(). Only those reserved pages are marked PG_reserved. But we still set PG_reserved on offline and check it on online. Following two commits removed both of them: * Commit 0ee5f4f31d36 ("mm/page_alloc.c: don't set pages PageReserved() when offlining") removed the set on offline. * Commit 5ecae6359e3a ("mm/memory_hotplug: drop PageReserved() check in online_pages_range()") removed the check on online. This means we set PG_reserved for hot-plugged memory at initialization is not helpful and a little different from bootmem initialization path. Now we can remove it. Memory hot-add and hot-remove have been tested. Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx> CC: Nathan Zimmer <nzimmer@xxxxxxx> CC: David Hildenbrand <david@xxxxxxxxxx> CC: Mike Rapoport (IBM) <rppt@xxxxxxxxxx> --- mm/mm_init.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/mm/mm_init.c b/mm/mm_init.c index 3ec04933f7fd..362ac4334b99 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -839,9 +839,8 @@ static void __init init_unavailable_range(unsigned long spfn, } /* - * Initially all pages are reserved - free ones are freed - * up by memblock_free_all() once the early boot process is - * done. Non-atomic initialization, single-pass. + * Free ones are freed up by memblock_free_all() once the early boot process + * is done. Non-atomic initialization, single-pass. * * All aligned pageblocks are initialized to the specified migratetype * (usually MIGRATE_MOVABLE). Besides setting the migratetype, no related @@ -892,8 +891,6 @@ void __meminit memmap_init_range(unsigned long size, int nid, unsigned long zone page = pfn_to_page(pfn); __init_single_page(page, pfn, zone, nid); - if (context == MEMINIT_HOTPLUG) - __SetPageReserved(page); /* * Usually, we want to mark the pageblock MIGRATE_MOVABLE, -- 2.34.1