In preparation for patch 6 and modularizing the code in general, split
can_change_pte_writable() into private and shared VMA parts. No functional
change intended.
Suggested-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Dev Jain <dev.jain@arm.com>
---
mm/mprotect.c | 50 ++++++++++++++++++++++++++++++++++++--------------
1 file changed, 36 insertions(+), 14 deletions(-)
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 4977f198168e..a1c7d8a4648d 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -40,11 +40,8 @@
#include "internal.h"
-bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
- pte_t pte)
+static bool maybe_change_pte_writable(struct vm_area_struct *vma, pte_t pte)
{
- struct page *page;
-
if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE)))
return false;
@@ -60,16 +57,32 @@ bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
if (userfaultfd_pte_wp(vma, pte))
return false;
- if (!(vma->vm_flags & VM_SHARED)) {
- /*
- * Writable MAP_PRIVATE mapping: We can only special-case on
- * exclusive anonymous pages, because we know that our
- * write-fault handler similarly would map them writable without
- * any additional checks while holding the PT lock.
- */
- page = vm_normal_page(vma, addr, pte);
- return page && PageAnon(page) && PageAnonExclusive(page);
- }
+ return true;
+}
+
+static bool can_change_private_pte_writable(struct vm_area_struct *vma,
+ unsigned long addr, pte_t pte)
+{
+ struct page *page;
+
+ if (!maybe_change_pte_writable(vma, pte))
+ return false;
+
+ /*
+ * Writable MAP_PRIVATE mapping: We can only special-case on
+ * exclusive anonymous pages, because we know that our
+ * write-fault handler similarly would map them writable without
+ * any additional checks while holding the PT lock.
+ */
+ page = vm_normal_page(vma, addr, pte);
+ return page && PageAnon(page) && PageAnonExclusive(page);
+}
+
+static bool can_change_shared_pte_writable(struct vm_area_struct *vma,
+ pte_t pte)
+{
+ if (!maybe_change_pte_writable(vma, pte))
+ return false;
VM_WARN_ON_ONCE(is_zero_pfn(pte_pfn(pte)) && pte_dirty(pte));
@@ -83,6 +96,15 @@ bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
return pte_dirty(pte);
}
+bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
+ pte_t pte)
+{
+ if (!(vma->vm_flags & VM_SHARED))
+ return can_change_private_pte_writable(vma, addr, pte);
+
+ return can_change_shared_pte_writable(vma, pte);
+}
+
static int mprotect_folio_pte_batch(struct folio *folio, pte_t *ptep,
pte_t pte, int max_nr_ptes)
{
--
2.30.2On 18 Jul 2025, at 5:02, Dev Jain wrote: > In preparation for patch 6 and modularizing the code in general, split > can_change_pte_writable() into private and shared VMA parts. No functional > change intended. > > Suggested-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> > Signed-off-by: Dev Jain <dev.jain@arm.com> > --- > mm/mprotect.c | 50 ++++++++++++++++++++++++++++++++++++-------------- > 1 file changed, 36 insertions(+), 14 deletions(-) > LGTM. Reviewed-by: Zi Yan <ziy@nvidia.com> Best Regards, Yan, Zi
On Fri, Jul 18, 2025 at 02:32:42PM +0530, Dev Jain wrote:
> In preparation for patch 6 and modularizing the code in general, split
> can_change_pte_writable() into private and shared VMA parts. No functional
> change intended.
>
> Suggested-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> Signed-off-by: Dev Jain <dev.jain@arm.com>
Great thanks! This is much clearer I think (of course being the
Suggested-by here makes me somewhat biased :P) :>)
LGTM, so:
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> ---
> mm/mprotect.c | 50 ++++++++++++++++++++++++++++++++++++--------------
> 1 file changed, 36 insertions(+), 14 deletions(-)
>
> diff --git a/mm/mprotect.c b/mm/mprotect.c
> index 4977f198168e..a1c7d8a4648d 100644
> --- a/mm/mprotect.c
> +++ b/mm/mprotect.c
> @@ -40,11 +40,8 @@
>
> #include "internal.h"
>
> -bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
> - pte_t pte)
> +static bool maybe_change_pte_writable(struct vm_area_struct *vma, pte_t pte)
> {
> - struct page *page;
> -
> if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE)))
> return false;
>
> @@ -60,16 +57,32 @@ bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
> if (userfaultfd_pte_wp(vma, pte))
> return false;
>
> - if (!(vma->vm_flags & VM_SHARED)) {
> - /*
> - * Writable MAP_PRIVATE mapping: We can only special-case on
> - * exclusive anonymous pages, because we know that our
> - * write-fault handler similarly would map them writable without
> - * any additional checks while holding the PT lock.
> - */
> - page = vm_normal_page(vma, addr, pte);
> - return page && PageAnon(page) && PageAnonExclusive(page);
> - }
> + return true;
> +}
> +
> +static bool can_change_private_pte_writable(struct vm_area_struct *vma,
> + unsigned long addr, pte_t pte)
> +{
> + struct page *page;
> +
> + if (!maybe_change_pte_writable(vma, pte))
> + return false;
> +
> + /*
> + * Writable MAP_PRIVATE mapping: We can only special-case on
> + * exclusive anonymous pages, because we know that our
> + * write-fault handler similarly would map them writable without
> + * any additional checks while holding the PT lock.
> + */
> + page = vm_normal_page(vma, addr, pte);
> + return page && PageAnon(page) && PageAnonExclusive(page);
> +}
> +
> +static bool can_change_shared_pte_writable(struct vm_area_struct *vma,
> + pte_t pte)
> +{
> + if (!maybe_change_pte_writable(vma, pte))
> + return false;
>
> VM_WARN_ON_ONCE(is_zero_pfn(pte_pfn(pte)) && pte_dirty(pte));
>
> @@ -83,6 +96,15 @@ bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
> return pte_dirty(pte);
> }
>
> +bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
> + pte_t pte)
> +{
> + if (!(vma->vm_flags & VM_SHARED))
> + return can_change_private_pte_writable(vma, addr, pte);
> +
> + return can_change_shared_pte_writable(vma, pte);
> +}
> +
> static int mprotect_folio_pte_batch(struct folio *folio, pte_t *ptep,
> pte_t pte, int max_nr_ptes)
> {
> --
> 2.30.2
>
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