mm: vmscan: evaluate the watermarks against the correct classzone

When deciding if kswapd is sleeping prematurely, the classzone is taken
into account but this is different to what balance_pgdat() and the
allocator are doing.  Specifically, the DMA zone will be checked based on
the classzone used when waking kswapd which could be for a GFP_KERNEL or
GFP_HIGHMEM request.  The lowmem reserve limit kicks in, the watermark is
not met and kswapd thinks it's sleeping prematurely keeping kswapd awake in
error.

Signed-off-by: Mel Gorman <[email protected]>
Reported-by: Pádraig Brady <[email protected]>
Tested-by: Pádraig Brady <[email protected]>
Tested-by: Andrew Lutomirski <[email protected]>
Acked-by: Rik van Riel <[email protected]>
Reviewed-by: Minchan Kim <[email protected]>
Cc: KOSAKI Motohiro <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 1 insertions, 1 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index a0245861934a..a51b3c9f05ba 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2344,7 +2344,7 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining,
 		}
 
 		if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone),
-							classzone_idx, 0))
+							i, 0))
 			all_zones_ok = false;
 		else
 			balanced += zone->present_pages;