From d61372bc41cfe91d6170434fc44b6af49cd2c755 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Tue, 22 Mar 2022 14:43:38 -0700 Subject: [PATCH] mm/page_alloc: drain the requested list first during bulk free Prior to the series, pindex 0 (order-0 MIGRATE_UNMOVABLE) was always skipped first and the precise reason is forgotten. A potential reason may have been to artificially preserve MIGRATE_UNMOVABLE but there is no reason why that would be optimal as it depends on the workload. The more likely reason is that it was less complicated to do a pre-increment instead of a post-increment in terms of overall code flow. As free_pcppages_bulk() now typically receives the pindex of the PCP list that exceeded high, always start draining that list. Link: https://lkml.kernel.org/r/20220217002227.5739-5-mgorman@techsingularity.net Signed-off-by: Mel Gorman Reviewed-by: Vlastimil Babka Tested-by: Aaron Lu Cc: Dave Hansen Cc: Jesper Dangaard Brouer Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 21f6837..ddb75c7 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1460,6 +1460,10 @@ static void free_pcppages_bulk(struct zone *zone, int count, * below while (list_empty(list)) loop. */ count = min(pcp->count, count); + + /* Ensure requested pindex is drained first. */ + pindex = pindex - 1; + while (count > 0) { struct list_head *list; int nr_pages; -- 2.7.4