From: Eric Dumazet <edumazet@xxxxxxxxxx> Subject: 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@xxxxxxxxx Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx> Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx> Acked-by: David Rientjes <rientjes@xxxxxxxxxx> Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Cc: Wei Xu <weixugc@xxxxxxxxxx> Cc: Greg Thelen <gthelen@xxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/page_alloc.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) --- a/mm/page_alloc.c~mm-page_alloc-call-check_new_pages-while-zone-spinlock-is-not-held +++ a/mm/page_alloc.c @@ -3665,10 +3665,10 @@ struct page *rmqueue(struct zone *prefer * 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 *prefer 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); _
