Commit 3313204c authored by Eric Dumazet's avatar Eric Dumazet Committed by Linus Torvalds
Browse files

mm/page_alloc: call check_new_pages() while zone spinlock is not held 

For high order pages not using pcp, rmqueue() is currently calling the
costly check_new_pages() while zone spinlock is held, and hard irqs
masked.

This is not needed, we can release the spinlock sooner to reduce zone
spinlock contention.

Note that after this patch, we call __mod_zone_freepage_state() before
deciding to leak the page because it is in bad state.

Link: https://lkml.kernel.org/r/20220304170215.1868106-1-eric.dumazet@gmail.com


Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarShakeel Butt <shakeelb@google.com>
Acked-by: default avatarDavid Rientjes <rientjes@google.com>
Acked-by: default avatarMel Gorman <mgorman@techsingularity.net>
Reviewed-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent fa7fc75f

mm/page_alloc.c

+9 −9
Original line number Diff line number Diff line
@@ -3665,10 +3665,10 @@ struct page *rmqueue(struct zone *preferred_zone, 
	 * allocate greater than order-1 page units with __GFP_NOFAIL.

	 */

	WARN_ON_ONCE((gfp_flags & __GFP_NOFAIL) && (order > 1));

	spin_lock_irqsave(&zone->lock, flags);



	do {

		page = NULL;

		spin_lock_irqsave(&zone->lock, flags);

		/*

		 * order-0 request can reach here when the pcplist is skipped

		 * due to non-CMA allocation context. HIGHATOMIC area is
@@ -3680,15 +3680,15 @@ struct page *rmqueue(struct zone *preferred_zone, 
			if (page)

				trace_mm_page_alloc_zone_locked(page, order, migratetype);

		}

		if (!page)

		if (!page) {

			page = __rmqueue(zone, order, migratetype, alloc_flags);

	} while (page && check_new_pages(page, order));

			if (!page)

				goto failed;



		}

		__mod_zone_freepage_state(zone, -(1 << order),

					  get_pcppage_migratetype(page));

		spin_unlock_irqrestore(&zone->lock, flags);

	} while (check_new_pages(page, order));



	__count_zid_vm_events(PGALLOC, page_zonenum(page), 1 << order);

	zone_statistics(preferred_zone, zone, 1);