zone_pcp_reset allegedly protects against a race with drain_pages using local_irq_save but this is bogus. local_irq_save only operates on the local CPU. If memory hotplug is running on CPU A and drain_pages is running on CPU B, disabling IRQs on CPU A does not affect CPU B and offers no protection. This patch deletes IRQ disable/enable on the grounds that IRQs protect nothing and assumes the existing hotplug paths guarantees the PCP cannot be used after zone_pcp_enable(). That should be the case already because all the pages have been freed and there is no page to put on the PCP lists. Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> --- Resending for email address correction and adding lists Changelog since v1 o Minimal fix mm/page_alloc.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 5e8aedb64b57..9bf0db982f14 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -8952,12 +8952,9 @@ void zone_pcp_enable(struct zone *zone) void zone_pcp_reset(struct zone *zone) { - unsigned long flags; int cpu; struct per_cpu_pageset *pset; - /* avoid races with drain_pages() */ - local_irq_save(flags); if (zone->pageset != &boot_pageset) { for_each_online_cpu(cpu) { pset = per_cpu_ptr(zone->pageset, cpu); @@ -8966,7 +8963,6 @@ void zone_pcp_reset(struct zone *zone) free_percpu(zone->pageset); zone->pageset = &boot_pageset; } - local_irq_restore(flags); } #ifdef CONFIG_MEMORY_HOTREMOVE