[PATCH] disable demotion during memory reclamation

[cuishiwei]

When a memory cgroup exceeds its memory limit, the system reclaims
its cold memory.However, if /sys/kernel/mm/numa/demotion_enabled is
set to 1, memory on fast memory nodes will also be demoted to slow 
memory nodes.

This demotion contradicts the goal of reclaiming cold memory within
the memcg.At this point, demoting cold memory from fast to slow nodes
is pointless;it doesn't reduce the memcg's memory usage. Therefore, 
we should set no_demotion when reclaiming memory in a memcg.

Signed-off-by: cuishiwei <cuishw@xxxxxxxxxx>
---
 mm/vmscan.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index ca9e1cd3cd68..1edf618a3604 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -6706,6 +6706,7 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
 		.may_unmap = 1,
 		.may_swap = !!(reclaim_options & MEMCG_RECLAIM_MAY_SWAP),
 		.proactive = !!(reclaim_options & MEMCG_RECLAIM_PROACTIVE),
+		.no_demotion = 1,
 	};
 	/*
 	 * Traverse the ZONELIST_FALLBACK zonelist of the current node to put
-- 
2.43.0