mm: mass constification of folio/page pointers

Now that page_pgoff() takes const pointers, we can constify the pointers
to a lot of functions.

Link: https://lkml.kernel.org/r/20241005200121.3231142-5-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

5 files changed, 28 insertions, 22 deletions

diff --git a/mm/internal.h b/mm/internal.h
index 8674f677304a..fd6373cb1c66 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1117,10 +1117,11 @@ void ClearPageHWPoisonTakenOff(struct page *page);
 bool take_page_off_buddy(struct page *page);
 bool put_page_back_buddy(struct page *page);
 struct task_struct *task_early_kill(struct task_struct *tsk, int force_early);
-void add_to_kill_ksm(struct task_struct *tsk, struct page *p,
+void add_to_kill_ksm(struct task_struct *tsk, const struct page *p,
 		     struct vm_area_struct *vma, struct list_head *to_kill,
 		     unsigned long ksm_addr);
-unsigned long page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
+unsigned long page_mapped_in_vma(const struct page *page,
+		struct vm_area_struct *vma);
 
 #else
 static inline void unmap_poisoned_folio(struct folio *folio, enum ttu_flags ttu)
diff --git a/mm/ksm.c b/mm/ksm.c
index b813225a806d..7ac59cde626c 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1051,7 +1051,8 @@ static int unmerge_ksm_pages(struct vm_area_struct *vma,
 	return err;
 }
 
-static inline struct ksm_stable_node *folio_stable_node(struct folio *folio)
+static inline
+struct ksm_stable_node *folio_stable_node(const struct folio *folio)
 {
 	return folio_test_ksm(folio) ? folio_raw_mapping(folio) : NULL;
 }
@@ -3067,7 +3068,7 @@ again:
 /*
  * Collect processes when the error hit an ksm page.
  */
-void collect_procs_ksm(struct folio *folio, struct page *page,
+void collect_procs_ksm(const struct folio *folio, const struct page *page,
 		struct list_head *to_kill, int force_early)
 {
 	struct ksm_stable_node *stable_node;
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index ea9d883c01c1..7ce7ba8586f5 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -445,7 +445,7 @@ static unsigned long dev_pagemap_mapping_shift(struct vm_area_struct *vma,
  * Schedule a process for later kill.
  * Uses GFP_ATOMIC allocations to avoid potential recursions in the VM.
  */
-static void __add_to_kill(struct task_struct *tsk, struct page *p,
+static void __add_to_kill(struct task_struct *tsk, const struct page *p,
 			  struct vm_area_struct *vma, struct list_head *to_kill,
 			  unsigned long addr)
 {
@@ -461,7 +461,7 @@ static void __add_to_kill(struct task_struct *tsk, struct page *p,
 	if (is_zone_device_page(p))
 		tk->size_shift = dev_pagemap_mapping_shift(vma, tk->addr);
 	else
-		tk->size_shift = page_shift(compound_head(p));
+		tk->size_shift = folio_shift(page_folio(p));
 
 	/*
 	 * Send SIGKILL if "tk->addr == -EFAULT". Also, as
@@ -486,7 +486,7 @@ static void __add_to_kill(struct task_struct *tsk, struct page *p,
 	list_add_tail(&tk->nd, to_kill);
 }
 
-static void add_to_kill_anon_file(struct task_struct *tsk, struct page *p,
+static void add_to_kill_anon_file(struct task_struct *tsk, const struct page *p,
 		struct vm_area_struct *vma, struct list_head *to_kill,
 		unsigned long addr)
 {
@@ -509,7 +509,7 @@ static bool task_in_to_kill_list(struct list_head *to_kill,
 	return false;
 }
 
-void add_to_kill_ksm(struct task_struct *tsk, struct page *p,
+void add_to_kill_ksm(struct task_struct *tsk, const struct page *p,
 		     struct vm_area_struct *vma, struct list_head *to_kill,
 		     unsigned long addr)
 {
@@ -606,8 +606,9 @@ struct task_struct *task_early_kill(struct task_struct *tsk, int force_early)
 /*
  * Collect processes when the error hit an anonymous page.
  */
-static void collect_procs_anon(struct folio *folio, struct page *page,
-		struct list_head *to_kill, int force_early)
+static void collect_procs_anon(const struct folio *folio,
+		const struct page *page, struct list_head *to_kill,
+		int force_early)
 {
 	struct task_struct *tsk;
 	struct anon_vma *av;
@@ -643,8 +644,9 @@ static void collect_procs_anon(struct folio *folio, struct page *page,
 /*
  * Collect processes when the error hit a file mapped page.
  */
-static void collect_procs_file(struct folio *folio, struct page *page,
-		struct list_head *to_kill, int force_early)
+static void collect_procs_file(const struct folio *folio,
+		const struct page *page, struct list_head *to_kill,
+		int force_early)
 {
 	struct vm_area_struct *vma;
 	struct task_struct *tsk;
@@ -680,7 +682,7 @@ static void collect_procs_file(struct folio *folio, struct page *page,
 }
 
 #ifdef CONFIG_FS_DAX
-static void add_to_kill_fsdax(struct task_struct *tsk, struct page *p,
+static void add_to_kill_fsdax(struct task_struct *tsk, const struct page *p,
 			      struct vm_area_struct *vma,
 			      struct list_head *to_kill, pgoff_t pgoff)
 {
@@ -691,7 +693,7 @@ static void add_to_kill_fsdax(struct task_struct *tsk, struct page *p,
 /*
  * Collect processes when the error hit a fsdax page.
  */
-static void collect_procs_fsdax(struct page *page,
+static void collect_procs_fsdax(const struct page *page,
 		struct address_space *mapping, pgoff_t pgoff,
 		struct list_head *to_kill, bool pre_remove)
 {
@@ -725,7 +727,7 @@ static void collect_procs_fsdax(struct page *page,
 /*
  * Collect the processes who have the corrupted page mapped to kill.
  */
-static void collect_procs(struct folio *folio, struct page *page,
+static void collect_procs(const struct folio *folio, const struct page *page,
 		struct list_head *tokill, int force_early)
 {
 	if (!folio->mapping)
diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
index 6b356853c04e..81839a9e74f1 100644
--- a/mm/page_vma_mapped.c
+++ b/mm/page_vma_mapped.c
@@ -337,9 +337,10 @@ next_pte:
  * outside the VMA or not present, returns -EFAULT.
  * Only valid for normal file or anonymous VMAs.
  */
-unsigned long page_mapped_in_vma(struct page *page, struct vm_area_struct *vma)
+unsigned long page_mapped_in_vma(const struct page *page,
+		struct vm_area_struct *vma)
 {
-	struct folio *folio = page_folio(page);
+	const struct folio *folio = page_folio(page);
 	struct page_vma_mapped_walk pvmw = {
 		.pfn = page_to_pfn(page),
 		.nr_pages = 1,
diff --git a/mm/rmap.c b/mm/rmap.c
index d4e5fe94fa92..c6c4d4ea29a7 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -496,7 +496,7 @@ void __init anon_vma_init(void)
  * concurrently without folio lock protection). See folio_lock_anon_vma_read()
  * which has already covered that, and comment above remap_pages().
  */
-struct anon_vma *folio_get_anon_vma(struct folio *folio)
+struct anon_vma *folio_get_anon_vma(const struct folio *folio)
 {
 	struct anon_vma *anon_vma = NULL;
 	unsigned long anon_mapping;
@@ -540,7 +540,7 @@ out:
  * reference like with folio_get_anon_vma() and then block on the mutex
  * on !rwc->try_lock case.
  */
-struct anon_vma *folio_lock_anon_vma_read(struct folio *folio,
+struct anon_vma *folio_lock_anon_vma_read(const struct folio *folio,
 					  struct rmap_walk_control *rwc)
 {
 	struct anon_vma *anon_vma = NULL;
@@ -1271,8 +1271,9 @@ static void __folio_set_anon(struct folio *folio, struct vm_area_struct *vma,
  * @vma:	the vm area in which the mapping is added
  * @address:	the user virtual address mapped
  */
-static void __page_check_anon_rmap(struct folio *folio, struct page *page,
-	struct vm_area_struct *vma, unsigned long address)
+static void __page_check_anon_rmap(const struct folio *folio,
+		const struct page *page, struct vm_area_struct *vma,
+		unsigned long address)
 {
 	/*
 	 * The page's anon-rmap details (mapping and index) are guaranteed to
@@ -2569,7 +2570,7 @@ void __put_anon_vma(struct anon_vma *anon_vma)
 		anon_vma_free(root);
 }
 
-static struct anon_vma *rmap_walk_anon_lock(struct folio *folio,
+static struct anon_vma *rmap_walk_anon_lock(const struct folio *folio,
 					    struct rmap_walk_control *rwc)
 {
 	struct anon_vma *anon_vma;