[PATCH 2/3] mm: add reclaim context as a new parameter in mem_cgroup_protected()

[Yafang Shao <laoar.shao@xxxxxxxxx>]

Add the reclaim context 'struct scan_control *sc' as a new parameter in
the function mem_cgroup_protected(), which will be used later. Change
the name of 'root' to 'target' for better understanding as this is a
targeted reclaim.
Also move the declaration and definition of the changed function into
mm/internal.h.

Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Roman Gushchin <guro@xxxxxx>
Cc: Chris Down <chris@xxxxxxxxxxxxxx>
Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
---
 include/linux/memcontrol.h |  9 ---------
 mm/memcontrol.c            | 14 ++++++++------
 mm/vmscan.c                |  2 +-
 3 files changed, 9 insertions(+), 16 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index d275c72c4f8e..b327857a1e7e 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -357,9 +357,6 @@ static inline unsigned long mem_cgroup_protection(struct mem_cgroup *memcg,
 		   READ_ONCE(memcg->memory.elow));
 }
 
-enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root,
-						struct mem_cgroup *memcg);
-
 int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm,
 			  gfp_t gfp_mask, struct mem_cgroup **memcgp,
 			  bool compound);
@@ -841,12 +838,6 @@ static inline unsigned long mem_cgroup_protection(struct mem_cgroup *memcg,
 	return 0;
 }
 
-static inline enum mem_cgroup_protection mem_cgroup_protected(
-	struct mem_cgroup *root, struct mem_cgroup *memcg)
-{
-	return MEMCG_PROT_NONE;
-}
-
 static inline int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm,
 					gfp_t gfp_mask,
 					struct mem_cgroup **memcgp,
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 5beea03dd58a..51dab7f2e714 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6367,6 +6367,7 @@ static unsigned long effective_protection(unsigned long usage,
  * mem_cgroup_protected - check if memory consumption is in the normal range
  * @root: the top ancestor of the sub-tree being checked
  * @memcg: the memory cgroup to check
+ * @sc: the reclaim context
  *
  * WARNING: This function is not stateless! It can only be used as part
  *          of a top-down tree iteration, not for isolated queries.
@@ -6377,8 +6378,9 @@ static unsigned long effective_protection(unsigned long usage,
  *     an unprotected supply of reclaimable memory from other cgroups.
  *   MEMCG_PROT_MIN: cgroup memory is protected
  */
-enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root,
-						struct mem_cgroup *memcg)
+enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *target,
+						struct mem_cgroup *memcg,
+						struct scan_control *sc)
 {
 	unsigned long usage, parent_usage;
 	struct mem_cgroup *parent;
@@ -6386,9 +6388,9 @@ enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root,
 	if (mem_cgroup_disabled())
 		return MEMCG_PROT_NONE;
 
-	if (!root)
-		root = root_mem_cgroup;
-	if (memcg == root)
+	if (!target)
+		target = root_mem_cgroup;
+	if (memcg == target)
 		return MEMCG_PROT_NONE;
 
 	usage = page_counter_read(&memcg->memory);
@@ -6400,7 +6402,7 @@ enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root,
 	if (!parent)
 		return MEMCG_PROT_NONE;
 
-	if (parent == root) {
+	if (parent == target) {
 		memcg->memory.emin = READ_ONCE(memcg->memory.min);
 		memcg->memory.elow = memcg->memory.low;
 		goto out;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 4c98512e2c9f..61c944e7f587 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2551,7 +2551,7 @@ static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc)
 		unsigned long reclaimed;
 		unsigned long scanned;
 
-		switch (mem_cgroup_protected(target_memcg, memcg)) {
+		switch (mem_cgroup_protected(target_memcg, memcg, sc)) {
 		case MEMCG_PROT_MIN:
 			/*
 			 * Hard protection.
-- 
2.18.2