From: Huang Ying <ying.huang@xxxxxxxxx>
Subject: autonuma: fix watermark checking in migrate_balanced_pgdat()
When zone_watermark_ok() is called in migrate_balanced_pgdat() to check
migration target node, the parameter classzone_idx (for requested zone) is
specified as 0 (ZONE_DMA). But when allocating memory for autonuma in
alloc_misplaced_dst_page(), the requested zone from GFP flags is
ZONE_MOVABLE. That is, the requested zone is different. The size of
lowmem_reserve for the different requested zone is different. And this
may cause some issues.
For example, in the zoneinfo of a test machine as below,
Node 0, zone DMA32
pages free 61592
min 29
low 454
high 879
spanned 1044480
present 442306
managed 425921
protection: (0, 0, 62457, 62457, 62457)
The free page number of ZONE_DMA32 is greater than "high watermark +
lowmem_reserve[ZONE_DMA]", but less than "high watermark +
lowmem_reserve[ZONE_MOVABLE]". And because __alloc_pages_node() in
alloc_misplaced_dst_page() requests ZONE_MOVABLE, the zone_watermark_ok()
on ZONE_DMA32 in migrate_balanced_pgdat() may always return true. So,
autonuma may not stop even when memory pressure in node 0 is heavy.
To fix the issue, ZONE_MOVABLE is used as parameter to call
zone_watermark_ok() in migrate_balanced_pgdat(). This makes it same as
requested zone in alloc_misplaced_dst_page(). So that
migrate_balanced_pgdat() returns false when memory pressure is heavy.
Link: http://lkml.kernel.org/r/20191101075727.26683-2-ying.huang@xxxxxxxxx
Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
Acked-by: Mel Gorman <mgorman@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Fengguang Wu <fengguang.wu@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/migrate.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/migrate.c~autonuma-fix-watermark-checking-in-migrate_balanced_pgdat
+++ a/mm/migrate.c
@@ -1859,7 +1859,7 @@ static bool migrate_balanced_pgdat(struc
if (!zone_watermark_ok(zone, 0,
high_wmark_pages(zone) +
nr_migrate_pages,
- 0, 0))
+ ZONE_MOVABLE, 0))
continue;
return true;
}
_
