lkml.org 
[lkml]   [2019]   [Nov]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[RFC 01/10] autonuma: Fix watermark checking in migrate_balanced_pgdat()
Date
From: Huang Ying <ying.huang@intel.com>

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.

Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
---
mm/migrate.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 513107baccd3..8f06bd37d927 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1954,7 +1954,7 @@ static bool migrate_balanced_pgdat(struct pglist_data *pgdat,
if (!zone_watermark_ok(zone, 0,
high_wmark_pages(zone) +
nr_migrate_pages,
- 0, 0))
+ ZONE_MOVABLE, 0))
continue;
return true;
}
--
2.23.0
\
 
 \ /
  Last update: 2019-11-01 08:58    [W:0.139 / U:0.624 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site