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.
Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
arch/s390/mm/mmap.c | 5 +++--
arch/sparc/kernel/sys_sparc_64.c | 3 ++-
arch/x86/mm/mmap.c | 7 ++++---
include/linux/sched/mm.h | 4 ++--
mm/util.c | 9 ++++++---
5 files changed, 17 insertions(+), 11 deletions(-)
diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c
index c0f619fb9ab3..a47c7133d82a 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 *const rlim_stack)
{
unsigned long gap = rlim_stack->rlim_cur;
unsigned long pad = stack_maxrandom_size() + stack_guard_gap;
@@ -169,7 +169,8 @@ unsigned long arch_get_unmapped_area_topdown(struct file *filp, unsigned long ad
* 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 *const mm,
+ const struct rlimit *const 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..1c243bb461b2 100644
--- a/arch/sparc/kernel/sys_sparc_64.c
+++ b/arch/sparc/kernel/sys_sparc_64.c
@@ -294,7 +294,8 @@ 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 *const mm,
+ const struct rlimit *const 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..13bde4ba2f24 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 *const 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 *const rlim_stack)
{
*legacy_base = mmap_legacy_base(random_factor, task_size);
if (mmap_is_legacy())
@@ -119,7 +119,8 @@ 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 *const mm,
+ const struct rlimit *const 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 f5a35efba7bf..24f08217cd95 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -431,7 +431,8 @@ static int mmap_is_legacy(const struct rlimit *const 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 *const rlim_stack)
{
#ifdef CONFIG_STACK_GROWSUP
/*
@@ -462,7 +463,8 @@ 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 *const mm,
+ const struct rlimit *const rlim_stack)
{
unsigned long random_factor = 0UL;
@@ -478,7 +480,8 @@ 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 *const mm,
+ const struct rlimit *const rlim_stack)
{
mm->mmap_base = TASK_UNMAPPED_BASE;
mm_flags_clear(MMF_TOPDOWN, mm);
--
2.47.2On 01.09.25 14:30, Max Kellermann wrote:
> 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.
>
> Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
> Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
> ---
[...]
> 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
Should both these cases also use *const?
(for the latter we probably don't care either, but maybe just to be
consistent)
--
Cheers
David / dhildenb
On Mon, Sep 1, 2025 at 3:58 PM David Hildenbrand <david@redhat.com> wrote:
> > 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
>
> Should both these cases also use *const?
>
> (for the latter we probably don't care either, but maybe just to be
> consistent)
Actually, it would *only* make sense on the latter, because the former
is a prototype...
On Mon, Sep 01, 2025 at 03:58:14PM +0200, David Hildenbrand wrote:
> On 01.09.25 14:30, Max Kellermann wrote:
> > 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.
> >
> > Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
> > Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
> > ---
>
> [...]
>
> > 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
>
> Should both these cases also use *const?
>
> (for the latter we probably don't care either, but maybe just to be
> consistent)
It'd be pretty hideous aesthetically. Really feel like we shouldn't be doing
it...
Imagine
static inline void foo(const struct mm_struct *const mm, const struct vm_area_struct *const vma,
const struct rlimit *const rlim_stack);
I mean that's _just not readable_.
>
> --
> Cheers
>
> David / dhildenb
>
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