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

[ Upstream commit 3313204c8ad553cf93f1ee8cc89456c73a7df938 ]

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: Eric Dumazet <edumazet@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Vlastimil 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Stable-dep-of: 281dd25c1a01 ("mm/page_alloc: let GFP_ATOMIC order-0 allocs access highatomic reserves")
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 264efa022fa9687bc590c7facc4075840bc16cc7..474150584ba48b3f04f3c3b029dde9cc59ae3d5d 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3698,10 +3698,10 @@ 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
@@ -3713,15 +3713,15 @@ 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);
+                       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);