[PATCH 01/11] mm: memcontrol: take a const folio in folio_memcg() and friends

[Tal Zussman]

The folio_memcg() family only reads from the folio, and everything it
calls already takes a const folio. Constify it, along with the page
wrappers built on top of it.

Signed-off-by: Tal Zussman <tz2294@xxxxxxxxxxxx>
---
 include/linux/memcontrol.h | 46 +++++++++++++++++++++++-----------------------
 mm/memcontrol.c            |  6 +++---
 2 files changed, 26 insertions(+), 26 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 945d7dbf1bb2..91ca94667d44 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -377,7 +377,7 @@ static inline struct mem_cgroup *obj_cgroup_memcg(struct obj_cgroup *objcg)
  * or NULL. This function assumes that the folio is known to have a
  * proper object cgroup pointer.
  */
-static inline struct obj_cgroup *folio_objcg(struct folio *folio)
+static inline struct obj_cgroup *folio_objcg(const struct folio *folio)
 {
 	unsigned long memcg_data = folio->memcg_data;
 
@@ -415,7 +415,7 @@ static inline struct obj_cgroup *folio_objcg(struct folio *folio)
  * Note: The caller should hold an rcu read lock or cgroup_mutex to protect
  * memcg associated with a folio from being released.
  */
-static inline struct mem_cgroup *folio_memcg(struct folio *folio)
+static inline struct mem_cgroup *folio_memcg(const struct folio *folio)
 {
 	struct obj_cgroup *objcg = folio_objcg(folio);
 
@@ -428,7 +428,7 @@ static inline struct mem_cgroup *folio_memcg(struct folio *folio)
  *
  * Returns true if folio is charged to a memory cgroup, otherwise returns false.
  */
-static inline bool folio_memcg_charged(struct folio *folio)
+static inline bool folio_memcg_charged(const struct folio *folio)
 {
 	return folio->memcg_data != 0;
 }
@@ -448,7 +448,7 @@ static inline bool folio_memcg_charged(struct folio *folio)
  * A caller should hold an rcu read lock to protect memcg associated with a
  * page from being released.
  */
-static inline struct mem_cgroup *folio_memcg_check(struct folio *folio)
+static inline struct mem_cgroup *folio_memcg_check(const struct folio *folio)
 {
 	/*
 	 * Because folio->memcg_data might be changed asynchronously
@@ -465,11 +465,11 @@ static inline struct mem_cgroup *folio_memcg_check(struct folio *folio)
 	return obj_cgroup_memcg(objcg);
 }
 
-static inline struct mem_cgroup *page_memcg_check(struct page *page)
+static inline struct mem_cgroup *page_memcg_check(const struct page *page)
 {
 	if (PageTail(page))
 		return NULL;
-	return folio_memcg_check((struct folio *)page);
+	return folio_memcg_check((const struct folio *)page);
 }
 
 static inline struct mem_cgroup *get_mem_cgroup_from_objcg(struct obj_cgroup *objcg)
@@ -494,14 +494,14 @@ static inline struct mem_cgroup *get_mem_cgroup_from_objcg(struct obj_cgroup *ob
  * that the folio has an associated memory cgroup. It's not safe to call
  * this function against some types of folios, e.g. slab folios.
  */
-static inline bool folio_memcg_kmem(struct folio *folio)
+static inline bool folio_memcg_kmem(const struct folio *folio)
 {
 	VM_BUG_ON_PGFLAGS(PageTail(&folio->page), &folio->page);
 	VM_BUG_ON_FOLIO(folio->memcg_data & MEMCG_DATA_OBJEXTS, folio);
 	return folio->memcg_data & MEMCG_DATA_KMEM;
 }
 
-static inline bool PageMemcgKmem(struct page *page)
+static inline bool PageMemcgKmem(const struct page *page)
 {
 	return folio_memcg_kmem(page_folio(page));
 }
@@ -743,7 +743,7 @@ struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm);
 
 struct mem_cgroup *get_mem_cgroup_from_current(void);
 
-struct mem_cgroup *get_mem_cgroup_from_folio(struct folio *folio);
+struct mem_cgroup *get_mem_cgroup_from_folio(const struct folio *folio);
 
 struct lruvec *folio_lruvec_lock(struct folio *folio);
 struct lruvec *folio_lruvec_lock_irq(struct folio *folio);
@@ -871,8 +871,8 @@ static inline bool mm_match_cgroup(struct mm_struct *mm,
 	return match;
 }
 
-struct cgroup_subsys_state *get_mem_cgroup_css_from_folio(struct folio *folio);
-ino_t page_cgroup_ino(struct page *page);
+struct cgroup_subsys_state *get_mem_cgroup_css_from_folio(const struct folio *folio);
+ino_t page_cgroup_ino(const struct page *page);
 
 static inline bool mem_cgroup_online(struct mem_cgroup *memcg)
 {
@@ -917,7 +917,7 @@ void mem_cgroup_print_oom_group(struct mem_cgroup *memcg);
 void mod_memcg_state(struct mem_cgroup *memcg,
 		     enum memcg_stat_item idx, int val);
 
-static inline void mod_memcg_page_state(struct page *page,
+static inline void mod_memcg_page_state(const struct page *page,
 					enum memcg_stat_item idx, int val)
 {
 	struct mem_cgroup *memcg;
@@ -951,7 +951,7 @@ void mod_lruvec_kmem_state(void *p, enum node_stat_item idx, int val);
 void count_memcg_events(struct mem_cgroup *memcg, enum vm_event_item idx,
 			unsigned long count);
 
-static inline void count_memcg_folio_events(struct folio *folio,
+static inline void count_memcg_folio_events(const struct folio *folio,
 		enum vm_event_item idx, unsigned long nr)
 {
 	struct mem_cgroup *memcg;
@@ -1045,22 +1045,22 @@ static inline struct mem_cgroup *obj_cgroup_memcg(struct obj_cgroup *objcg)
 
 #define root_mem_cgroup		(NULL)
 
-static inline struct mem_cgroup *folio_memcg(struct folio *folio)
+static inline struct mem_cgroup *folio_memcg(const struct folio *folio)
 {
 	return NULL;
 }
 
-static inline bool folio_memcg_charged(struct folio *folio)
+static inline bool folio_memcg_charged(const struct folio *folio)
 {
 	return false;
 }
 
-static inline struct mem_cgroup *folio_memcg_check(struct folio *folio)
+static inline struct mem_cgroup *folio_memcg_check(const struct folio *folio)
 {
 	return NULL;
 }
 
-static inline struct mem_cgroup *page_memcg_check(struct page *page)
+static inline struct mem_cgroup *page_memcg_check(const struct page *page)
 {
 	return NULL;
 }
@@ -1070,12 +1070,12 @@ static inline struct mem_cgroup *get_mem_cgroup_from_objcg(struct obj_cgroup *ob
 	return NULL;
 }
 
-static inline bool folio_memcg_kmem(struct folio *folio)
+static inline bool folio_memcg_kmem(const struct folio *folio)
 {
 	return false;
 }
 
-static inline bool PageMemcgKmem(struct page *page)
+static inline bool PageMemcgKmem(const struct page *page)
 {
 	return false;
 }
@@ -1208,7 +1208,7 @@ static inline struct mem_cgroup *get_mem_cgroup_from_current(void)
 	return NULL;
 }
 
-static inline struct mem_cgroup *get_mem_cgroup_from_folio(struct folio *folio)
+static inline struct mem_cgroup *get_mem_cgroup_from_folio(const struct folio *folio)
 {
 	return NULL;
 }
@@ -1366,7 +1366,7 @@ static inline void mod_memcg_state(struct mem_cgroup *memcg,
 {
 }
 
-static inline void mod_memcg_page_state(struct page *page,
+static inline void mod_memcg_page_state(const struct page *page,
 					enum memcg_stat_item idx, int val)
 {
 }
@@ -1431,7 +1431,7 @@ static inline void count_memcg_events(struct mem_cgroup *memcg,
 {
 }
 
-static inline void count_memcg_folio_events(struct folio *folio,
+static inline void count_memcg_folio_events(const struct folio *folio,
 		enum vm_event_item idx, unsigned long nr)
 {
 }
@@ -1861,7 +1861,7 @@ static inline void count_objcg_events(struct obj_cgroup *objcg,
 {
 }
 
-static inline ino_t page_cgroup_ino(struct page *page)
+static inline ino_t page_cgroup_ino(const struct page *page)
 {
 	return 0;
 }
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 5b9e0ebd42ae..b9bf655cdd2d 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -331,7 +331,7 @@ EXPORT_SYMBOL(memcg_bpf_enabled_key);
  * If memcg is bound to a traditional hierarchy, the css of root_mem_cgroup
  * is returned.
  */
-struct cgroup_subsys_state *get_mem_cgroup_css_from_folio(struct folio *folio)
+struct cgroup_subsys_state *get_mem_cgroup_css_from_folio(const struct folio *folio)
 {
 	struct mem_cgroup *memcg;
 
@@ -356,7 +356,7 @@ struct cgroup_subsys_state *get_mem_cgroup_css_from_folio(struct folio *folio)
  * after page_cgroup_ino() returns, so it only should be used by callers that
  * do not care (such as procfs interfaces).
  */
-ino_t page_cgroup_ino(struct page *page)
+ino_t page_cgroup_ino(const struct page *page)
 {
 	struct mem_cgroup *memcg;
 	unsigned long ino = 0;
@@ -1220,7 +1220,7 @@ struct mem_cgroup *get_mem_cgroup_from_current(void)
  *
  * See folio_memcg() for folio->objcg/memcg binding rules.
  */
-struct mem_cgroup *get_mem_cgroup_from_folio(struct folio *folio)
+struct mem_cgroup *get_mem_cgroup_from_folio(const struct folio *folio)
 {
 	struct mem_cgroup *memcg;
 

-- 
2.39.5