linux-kernel - [PATCH v2 1/2] mm: introduce pmd|pte_needs_soft_dirty

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Message-Id: <20240607211358.4660-2-21cnbao@gmail.com>
Date: Sat,  8 Jun 2024 09:13:57 +1200
From: Barry Song <21cnbao@...il.com>
To: akpm@...ux-foundation.org,
	david@...hat.com,
	linux-mm@...ck.org
Cc: chrisl@...nel.org,
	kasong@...cent.com,
	linux-kernel@...r.kernel.org,
	minchan@...nel.org,
	ryan.roberts@....com,
	surenb@...gle.com,
	v-songbaohua@...o.com,
	willy@...radead.org
Subject: [PATCH v2 1/2] mm: introduce pmd|pte_needs_soft_dirty_wp helpers for softdirty write-protect

From: Barry Song <v-songbaohua@...o.com>

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.

Suggested-by: David Hildenbrand <david@...hat.com>
Signed-off-by: Barry Song <v-songbaohua@...o.com>
---
 mm/gup.c         |  4 ++--
 mm/huge_memory.c |  2 +-
 mm/internal.h    | 10 ++++++++++
 mm/mprotect.c    |  2 +-
 4 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 83e279731d1b..f15756a3646a 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -820,7 +820,7 @@ 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);
 }
@@ -941,7 +941,7 @@ 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);
 }
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 3fbcd77f5957..b29daea9c317 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1625,7 +1625,7 @@ 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? */
diff --git a/mm/internal.h b/mm/internal.h
index 12e95fdf61e9..b7853fd57d9a 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1348,6 +1348,16 @@ 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)
 {
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 888ef66468db..222ab434da54 100644
--- a/mm/mprotect.c
+++ b/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? */
-- 
2.34.1