[PATCH 06/12] mm/util: add `const` to several pointer parameters

Max Kellermann posted 12 patches 1 month ago
There is a newer version of this series
[PATCH 06/12] mm/util: add `const` to several pointer parameters
Posted by Max Kellermann 1 month ago
For improved const-correctness.

Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
---
 include/linux/mm.h      |  6 +++---
 include/linux/pagemap.h |  2 +-
 mm/util.c               | 10 +++++-----
 3 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index a795deef93eb..48fe838723ed 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -986,7 +986,7 @@ static inline bool vma_is_shmem(const struct vm_area_struct *vma) { return false
 static inline bool vma_is_anon_shmem(const struct vm_area_struct *vma) { return false; }
 #endif
 
-int vma_is_stack_for_current(struct vm_area_struct *vma);
+int vma_is_stack_for_current(const struct vm_area_struct *vma);
 
 /* flush_tlb_range() takes a vma, not a mm, and can care about flags */
 #define TLB_FLUSH_VMA(mm,flags) { .vm_mm = (mm), .vm_flags = (flags) }
@@ -2585,7 +2585,7 @@ void folio_add_pin(struct folio *folio);
 
 int account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc);
 int __account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc,
-			struct task_struct *task, bool bypass_rlim);
+			const struct task_struct *task, bool bypass_rlim);
 
 struct kvec;
 struct page *get_dump_page(unsigned long addr, int *locked);
@@ -3348,7 +3348,7 @@ void anon_vma_interval_tree_verify(struct anon_vma_chain *node);
 	     avc; avc = anon_vma_interval_tree_iter_next(avc, start, last))
 
 /* mmap.c */
-extern int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin);
+extern int __vm_enough_memory(const struct mm_struct *mm, long pages, int cap_sys_admin);
 extern int insert_vm_struct(struct mm_struct *, struct vm_area_struct *);
 extern void exit_mmap(struct mm_struct *);
 bool mmap_read_lock_maybe_expand(struct mm_struct *mm, struct vm_area_struct *vma,
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 87411e7f2dba..eb50e0124cd0 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -549,7 +549,7 @@ static inline void filemap_nr_thps_dec(struct address_space *mapping)
 #endif
 }
 
-struct address_space *folio_mapping(struct folio *);
+struct address_space *folio_mapping(const struct folio *);
 
 /**
  * folio_flush_mapping - Find the file mapping this folio belongs to.
diff --git a/mm/util.c b/mm/util.c
index d235b74f7aff..241d2eaf26ca 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -315,7 +315,7 @@ void *memdup_user_nul(const void __user *src, size_t len)
 EXPORT_SYMBOL(memdup_user_nul);
 
 /* Check if the vma is being used as a stack by this task */
-int vma_is_stack_for_current(struct vm_area_struct *vma)
+int vma_is_stack_for_current(const struct vm_area_struct *vma)
 {
 	struct task_struct * __maybe_unused t = current;
 
@@ -410,7 +410,7 @@ unsigned long arch_mmap_rnd(void)
 	return rnd << PAGE_SHIFT;
 }
 
-static int mmap_is_legacy(struct rlimit *rlim_stack)
+static int mmap_is_legacy(const struct rlimit *rlim_stack)
 {
 	if (current->personality & ADDR_COMPAT_LAYOUT)
 		return 1;
@@ -504,7 +504,7 @@ EXPORT_SYMBOL_IF_KUNIT(arch_pick_mmap_layout);
  * * -ENOMEM if RLIMIT_MEMLOCK would be exceeded.
  */
 int __account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc,
-			struct task_struct *task, bool bypass_rlim)
+			const struct task_struct *task, bool bypass_rlim)
 {
 	unsigned long locked_vm, limit;
 	int ret = 0;
@@ -688,7 +688,7 @@ struct anon_vma *folio_anon_vma(const struct folio *folio)
  * You can call this for folios which aren't in the swap cache or page
  * cache and it will return NULL.
  */
-struct address_space *folio_mapping(struct folio *folio)
+struct address_space *folio_mapping(const struct folio *folio)
 {
 	struct address_space *mapping;
 
@@ -926,7 +926,7 @@ EXPORT_SYMBOL_GPL(vm_memory_committed);
  * Note this is a helper function intended to be used by LSMs which
  * wish to use this logic.
  */
-int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
+int __vm_enough_memory(const struct mm_struct *mm, long pages, int cap_sys_admin)
 {
 	long allowed;
 	unsigned long bytes_failed;
-- 
2.47.2
Re: [PATCH 06/12] mm/util: add `const` to several pointer parameters
Posted by Vishal Moola (Oracle) 1 month ago
On Fri, Aug 29, 2025 at 08:31:53PM +0200, Max Kellermann wrote:
> For improved const-correctness.
> 
> Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -549,7 +549,7 @@ static inline void filemap_nr_thps_dec(struct address_space *mapping)
>  #endif
>  }
>  
> -struct address_space *folio_mapping(struct folio *);
> +struct address_space *folio_mapping(const struct folio *);

Can we make this (const struct folio *folio) like below. Its more
readable imo.

With or without that change, feel free to add:
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>

> +struct address_space *folio_mapping(const struct folio *folio)
>  {
>  	struct address_space *mapping;
>