mm/demotion: demote pages according to allocation fallback order

Currently, a higher tier node can only be demoted to selected nodes on the
next lower tier as defined by the demotion path.  This strict demotion
order does not work in all use cases (e.g.  some use cases may want to
allow cross-socket demotion to another node in the same demotion tier as a
fallback when the preferred demotion node is out of space).  This demotion
order is also inconsistent with the page allocation fallback order when
all the nodes in a higher tier are out of space: The page allocation can
fall back to any node from any lower tier, whereas the demotion order
doesn't allow that currently.

This patch adds support to get all the allowed demotion targets for a
memory tier.  demote_page_list() function is now modified to utilize this
allowed node mask as the fallback allocation mask.

Link: https://lkml.kernel.org/r/20220818131042.113280-9-aneesh.kumar@linux.ibm.com
Signed-off-by: Jagdish Gediya <jvgediya.oss@gmail.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Wei Xu <weixugc@google.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Bharata B Rao <bharata@amd.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hesham Almatary <hesham.almatary@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tim Chen <tim.c.chen@intel.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/include/linux/memory-tiers.h b/include/linux/memory-tiers.h
index 7ca52ad2789f..42791554b9b9 100644
--- a/include/linux/memory-tiers.h
+++ b/include/linux/memory-tiers.h
@@ -5,6 +5,7 @@
 #include <linux/types.h>
 #include <linux/nodemask.h>
 #include <linux/kref.h>
+#include <linux/mmzone.h>
 /*
  * Each tier cover a abstrace distance chunk size of 128
  */
@@ -38,11 +39,17 @@ void init_node_memory_type(int node, struct memory_dev_type *default_type);
 void clear_node_memory_type(int node, struct memory_dev_type *memtype);
 #ifdef CONFIG_MIGRATION
 int next_demotion_node(int node);
+void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets);
 #else
 static inline int next_demotion_node(int node)
 {
 	return NUMA_NO_NODE;
 }
+
+static inline void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets)
+{
+	*targets = NODE_MASK_NONE;
+}
 #endif
 
 #else
@@ -75,5 +82,10 @@ static inline int next_demotion_node(int node)
 {
 	return NUMA_NO_NODE;
 }
+
+static inline void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets)
+{
+	*targets = NODE_MASK_NONE;
+}
 #endif	/* CONFIG_NUMA */
 #endif  /* _LINUX_MEMORY_TIERS_H */