From 27cacaad16c549ce5dd30ae84100b7e680536822 Mon Sep 17 00:00:00 2001 From: Oscar Salvador Date: Wed, 30 Jun 2021 18:52:46 -0700 Subject: [PATCH] mm,memory_hotplug: drop unneeded locking Currently, memory-hotplug code takes zone's span_writelock and pgdat's resize_lock when resizing the node/zone's spanned pages via {move_pfn_range_to_zone(),remove_pfn_range_from_zone()} and when resizing node and zone's present pages via adjust_present_page_count(). These locks are also taken during the initialization of the system at boot time, where it protects parallel struct page initialization, but they should not really be needed in memory-hotplug where all operations are a) synchronized on device level and b) serialized by the mem_hotplug_lock lock. [akpm@linux-foundation.org: remove now-unused locals] Link: https://lkml.kernel.org/r/20210531093958.15021-1-osalvador@suse.de Signed-off-by: Oscar Salvador Acked-by: David Hildenbrand Acked-by: Michal Hocko Cc: Anshuman Khandual Cc: Vlastimil Babka Cc: Pavel Tatashin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory_hotplug.c | 16 +--------------- 1 file changed, 1 insertion(+), 15 deletions(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 1a9568d..553c527 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -329,7 +329,6 @@ static void shrink_zone_span(struct zone *zone, unsigned long start_pfn, unsigned long pfn; int nid = zone_to_nid(zone); - zone_span_writelock(zone); if (zone->zone_start_pfn == start_pfn) { /* * If the section is smallest section in the zone, it need @@ -362,7 +361,6 @@ static void shrink_zone_span(struct zone *zone, unsigned long start_pfn, zone->spanned_pages = 0; } } - zone_span_writeunlock(zone); } static void update_pgdat_span(struct pglist_data *pgdat) @@ -399,7 +397,7 @@ void __ref remove_pfn_range_from_zone(struct zone *zone, { const unsigned long end_pfn = start_pfn + nr_pages; struct pglist_data *pgdat = zone->zone_pgdat; - unsigned long pfn, cur_nr_pages, flags; + unsigned long pfn, cur_nr_pages; /* Poison struct pages because they are now uninitialized again. */ for (pfn = start_pfn; pfn < end_pfn; pfn += cur_nr_pages) { @@ -424,10 +422,8 @@ void __ref remove_pfn_range_from_zone(struct zone *zone, clear_zone_contiguous(zone); - pgdat_resize_lock(zone->zone_pgdat, &flags); shrink_zone_span(zone, start_pfn, start_pfn + nr_pages); update_pgdat_span(pgdat); - pgdat_resize_unlock(zone->zone_pgdat, &flags); set_zone_contiguous(zone); } @@ -634,19 +630,13 @@ void __ref move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn, { struct pglist_data *pgdat = zone->zone_pgdat; int nid = pgdat->node_id; - unsigned long flags; clear_zone_contiguous(zone); - /* TODO Huh pgdat is irqsave while zone is not. It used to be like that before */ - pgdat_resize_lock(pgdat, &flags); - zone_span_writelock(zone); if (zone_is_empty(zone)) init_currently_empty_zone(zone, start_pfn, nr_pages); resize_zone_range(zone, start_pfn, nr_pages); - zone_span_writeunlock(zone); resize_pgdat_range(pgdat, start_pfn, nr_pages); - pgdat_resize_unlock(pgdat, &flags); /* * Subsection population requires care in pfn_to_online_page(). @@ -736,12 +726,8 @@ struct zone *zone_for_pfn_range(int online_type, int nid, unsigned start_pfn, */ void adjust_present_page_count(struct zone *zone, long nr_pages) { - unsigned long flags; - zone->present_pages += nr_pages; - pgdat_resize_lock(zone->zone_pgdat, &flags); zone->zone_pgdat->node_present_pages += nr_pages; - pgdat_resize_unlock(zone->zone_pgdat, &flags); } int mhp_init_memmap_on_memory(unsigned long pfn, unsigned long nr_pages, -- 2.7.4