mm: constify arch_pick_mmap_layout() for improved const-correctness

This function only reads from the rlimit pointer (but writes to the
mm_struct pointer which is kept without `const`).

All callees are already const-ified or (internal functions) are being
constified by this patch.

Link: https://lkml.kernel.org/r/20250901205021.3573313-9-max.kellermann@ionos.com
Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christian Zankel <chris@zankel.net>
Cc: David Rientjes <rientjes@google.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Bottomley <james.bottomley@HansenPartnership.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jocelyn Falempe <jfalempe@redhat.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Nysal Jan K.A" <nysal@linux.ibm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Huth <thuth@redhat.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

5 files changed, 11 insertions, 11 deletions

diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c
index e188cb6d4946..197c1d9497a7 100644
--- a/arch/s390/mm/mmap.c
+++ b/arch/s390/mm/mmap.c
@@ -47,7 +47,7 @@ static unsigned long mmap_base_legacy(unsigned long rnd)
 }
 
 static inline unsigned long mmap_base(unsigned long rnd,
-				      struct rlimit *rlim_stack)
+				      const struct rlimit *rlim_stack)
 {
 	unsigned long gap = rlim_stack->rlim_cur;
 	unsigned long pad = stack_maxrandom_size() + stack_guard_gap;
@@ -169,7 +169,7 @@ check_asce_limit:
  * This function, called very early during the creation of a new
  * process VM image, sets up which VM layout function to use:
  */
-void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
+void arch_pick_mmap_layout(struct mm_struct *mm, const struct rlimit *rlim_stack)
 {
 	unsigned long random_factor = 0UL;
 
diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c
index 785e9909340f..55faf2effa46 100644
--- a/arch/sparc/kernel/sys_sparc_64.c
+++ b/arch/sparc/kernel/sys_sparc_64.c
@@ -294,7 +294,7 @@ static unsigned long mmap_rnd(void)
 	return rnd << PAGE_SHIFT;
 }
 
-void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
+void arch_pick_mmap_layout(struct mm_struct *mm, const struct rlimit *rlim_stack)
 {
 	unsigned long random_factor = mmap_rnd();
 	unsigned long gap;
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index 708f85dc9380..82f3a987f7cf 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -80,7 +80,7 @@ unsigned long arch_mmap_rnd(void)
 }
 
 static unsigned long mmap_base(unsigned long rnd, unsigned long task_size,
-			       struct rlimit *rlim_stack)
+			       const struct rlimit *rlim_stack)
 {
 	unsigned long gap = rlim_stack->rlim_cur;
 	unsigned long pad = stack_maxrandom_size(task_size) + stack_guard_gap;
@@ -110,7 +110,7 @@ static unsigned long mmap_legacy_base(unsigned long rnd,
  */
 static void arch_pick_mmap_base(unsigned long *base, unsigned long *legacy_base,
 		unsigned long random_factor, unsigned long task_size,
-		struct rlimit *rlim_stack)
+		const struct rlimit *rlim_stack)
 {
 	*legacy_base = mmap_legacy_base(random_factor, task_size);
 	if (mmap_is_legacy())
@@ -119,7 +119,7 @@ static void arch_pick_mmap_base(unsigned long *base, unsigned long *legacy_base,
 		*base = mmap_base(random_factor, task_size, rlim_stack);
 }
 
-void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
+void arch_pick_mmap_layout(struct mm_struct *mm, const struct rlimit *rlim_stack)
 {
 	if (mmap_is_legacy())
 		mm_flags_clear(MMF_TOPDOWN, mm);
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index 2201da0afecc..0232d983b715 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -178,7 +178,7 @@ static inline void mm_update_next_owner(struct mm_struct *mm)
 #endif
 
 extern void arch_pick_mmap_layout(struct mm_struct *mm,
-				  struct rlimit *rlim_stack);
+				  const struct rlimit *rlim_stack);
 
 unsigned long
 arch_get_unmapped_area(struct file *filp, unsigned long addr,
@@ -211,7 +211,7 @@ generic_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
 				  unsigned long flags, vm_flags_t vm_flags);
 #else
 static inline void arch_pick_mmap_layout(struct mm_struct *mm,
-					 struct rlimit *rlim_stack) {}
+					 const struct rlimit *rlim_stack) {}
 #endif
 
 static inline bool in_vfork(struct task_struct *tsk)
diff --git a/mm/util.c b/mm/util.c
index 391f6e7daf83..732a2dfcaec7 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -431,7 +431,7 @@ static int mmap_is_legacy(const struct rlimit *rlim_stack)
 #define MIN_GAP		(SZ_128M)
 #define MAX_GAP		(STACK_TOP / 6 * 5)
 
-static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
+static unsigned long mmap_base(const unsigned long rnd, const struct rlimit *rlim_stack)
 {
 #ifdef CONFIG_STACK_GROWSUP
 	/*
@@ -462,7 +462,7 @@ static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
 #endif
 }
 
-void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
+void arch_pick_mmap_layout(struct mm_struct *mm, const struct rlimit *rlim_stack)
 {
 	unsigned long random_factor = 0UL;
 
@@ -478,7 +478,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
 	}
 }
 #elif defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
-void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
+void arch_pick_mmap_layout(struct mm_struct *mm, const struct rlimit *rlim_stack)
 {
 	mm->mmap_base = TASK_UNMAPPED_BASE;
 	mm_flags_clear(MMF_TOPDOWN, mm);