[PATCH 4/7] mm/page_alloc: Remove mistaken page == NULL check in rmqueue

Mel Gorman
2022-06-13T17:36:24Z

If a page allocation fails, the ZONE_BOOSTER_WATERMARK should be tested,
cleared and kswapd woken whether the allocation attempt was via the PCP
or directly via the buddy list.

Remove the page == NULL so the ZONE_BOOSTED_WATERMARK bit is checked
unconditionally. As it is unlikely that ZONE_BOOSTED_WATERMARK is set,
mark the branch accordingly.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
---
mm/page_alloc.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 44d198af4b35..7fb262eeec2f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3777,12 +3777,10 @@ struct page *rmqueue(struct zone *preferred_zone,

page = rmqueue_buddy(preferred_zone, zone, order, alloc_flags,
migratetype);
- if (unlikely(!page))
- return NULL;

out:
/* Separate test+clear to avoid unnecessary atomics */
- if (test_bit(ZONE_BOOSTED_WATERMARK, &zone->flags)) {
+ if (unlikely(test_bit(ZONE_BOOSTED_WATERMARK, &zone->flags))) {
clear_bit(ZONE_BOOSTED_WATERMARK, &zone->flags);
wakeup_kswapd(zone, 0, 0, zone_idx(zone));
}
--
2.35.3