Already two people (including me) tried to offline subsections, because the function looks like it can deal with it. But we really can only online/offline full sections (e.g., we can only mark full sections online/offline via SECTION_IS_ONLINE). Add a simple safety net that to document the restriction now. Current users (core and powernv/memtrace) respect these restrictions. Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx> Cc: Baoquan He <bhe@xxxxxxxxxx> Cc: Pankaj Gupta <pankaj.gupta.linux@xxxxxxxxx> Cc: Oscar Salvador <osalvador@xxxxxxx> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx> --- mm/memory_hotplug.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index c781d386d87f9..6856702af68d9 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -801,6 +801,11 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int ret; struct memory_notify arg; + /* We can only online full sections (e.g., SECTION_IS_ONLINE) */ + if (WARN_ON_ONCE(!nr_pages || + !IS_ALIGNED(pfn | nr_pages, PAGES_PER_SECTION))) + return -EINVAL; + mem_hotplug_begin(); /* associate pfn range with the zone */ @@ -1483,6 +1488,11 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages) struct memory_notify arg; char *reason; + /* We can only offline full sections (e.g., SECTION_IS_ONLINE) */ + if (WARN_ON_ONCE(!nr_pages || + !IS_ALIGNED(start_pfn | nr_pages, PAGES_PER_SECTION))) + return -EINVAL; + mem_hotplug_begin(); /* -- 2.26.2
