Re: [PATCH 3/4] mm, page_allocator: Only use per-cpu allocator for irq-safe requests

From: Hillf Danton
Date: Thu Jan 05 2017 - 22:27:52 EST



On Wednesday, January 04, 2017 7:11 PM Mel Gorman wrote:
> @@ -2647,9 +2644,8 @@ static struct page *rmqueue_pcplist(struct zone *preferred_zone,
> struct list_head *list;
> bool cold = ((gfp_flags & __GFP_COLD) != 0);
> struct page *page;
> - unsigned long flags;
>
> - local_irq_save(flags);
> + preempt_disable();
> pcp = &this_cpu_ptr(zone->pageset)->pcp;
> list = &pcp->lists[migratetype];
> page = __rmqueue_pcplist(zone, order, gfp_flags, migratetype,
> @@ -2658,7 +2654,7 @@ static struct page *rmqueue_pcplist(struct zone *preferred_zone,
> __count_zid_vm_events(PGALLOC, page_zonenum(page), 1 << order);
> zone_statistics(preferred_zone, zone, gfp_flags);
> }
> - local_irq_restore(flags);
> + preempt_enable();
> return page;
> }
>
With PREEMPT configured, preempt_enable() adds entry point to schedule().
Is that needed when we try to allocate a page?

Hillf