mm: introduce pmd|pte_needs_soft_dirty_wp helpers for softdirty write-protect

Patch series "mm: introduce pmd|pte_needs_soft_dirty_wp helpers and
utilize them", v2.


This patchset introduces the pte_need_soft_dirty_wp and
pmd_need_soft_dirty_wp helpers to determine if write protection is
required for softdirty tracking.  These helpers enhance code readability
and improve the overall appearance.

They are then utilized in gup, mprotect, swap, and other related
functions.


This patch (of 2): 

This patch introduces the pte_needs_soft_dirty_wp and
pmd_needs_soft_dirty_wp helpers to determine if write protection is
required for softdirty tracking.  This can enhance code readability and
improve its overall appearance.  These new helpers are then utilized in
gup, huge_memory, and mprotect.

Link: https://lkml.kernel.org/r/20240607211358.4660-1-21cnbao@gmail.com
Link: https://lkml.kernel.org/r/20240607211358.4660-2-21cnbao@gmail.comSigned-off-by: Barry Song <v-songbaohua@oppo.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Kairui Song <kasong@tencent.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/gup.c

@@ -771,7 +771,7 @@ static inline bool can_follow_write_pmd(pmd_t pmd, struct page *page,
 		return false;
 
 	/* ... and a write-fault isn't required for other reasons. */
-	if (vma_soft_dirty_enabled(vma) && !pmd_soft_dirty(pmd))
+	if (pmd_needs_soft_dirty_wp(vma, pmd))
 		return false;
 	return !userfaultfd_huge_pmd_wp(vma, pmd);
 }
@@ -892,7 +892,7 @@ static inline bool can_follow_write_pte(pte_t pte, struct page *page,
 		return false;
 
 	/* ... and a write-fault isn't required for other reasons. */
-	if (vma_soft_dirty_enabled(vma) && !pte_soft_dirty(pte))
+	if (pte_needs_soft_dirty_wp(vma, pte))
 		return false;
 	return !userfaultfd_pte_wp(vma, pte);
 }

mm/huge_memory.c

@@ -1626,7 +1626,7 @@ static inline bool can_change_pmd_writable(struct vm_area_struct *vma,
 		return false;
 
 	/* Do we need write faults for softdirty tracking? */
-	if (vma_soft_dirty_enabled(vma) && !pmd_soft_dirty(pmd))
+	if (pmd_needs_soft_dirty_wp(vma, pmd))
 		return false;
 
 	/* Do we need write faults for uffd-wp tracking? */

mm/internal.h

@@ -1333,6 +1333,16 @@ static inline bool vma_soft_dirty_enabled(struct vm_area_struct *vma)
 	return !(vma->vm_flags & VM_SOFTDIRTY);
 }
 
+static inline bool pmd_needs_soft_dirty_wp(struct vm_area_struct *vma, pmd_t pmd)
+{
+	return vma_soft_dirty_enabled(vma) && !pmd_soft_dirty(pmd);
+}
+
+static inline bool pte_needs_soft_dirty_wp(struct vm_area_struct *vma, pte_t pte)
+{
+	return vma_soft_dirty_enabled(vma) && !pte_soft_dirty(pte);
+}
+
 static inline void vma_iter_config(struct vma_iterator *vmi,
 		unsigned long index, unsigned long last)
 {

mm/mprotect.c

@@ -53,7 +53,7 @@ bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
 		return false;
 
 	/* Do we need write faults for softdirty tracking? */
-	if (vma_soft_dirty_enabled(vma) && !pte_soft_dirty(pte))
+	if (pte_needs_soft_dirty_wp(vma, pte))
 		return false;
 
 	/* Do we need write faults for uffd-wp tracking? */