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Message-Id: <20250905103651.489197-2-zhangchunyan@iscas.ac.cn>
Date: Fri, 5 Sep 2025 18:36:47 +0800
From: Chunyan Zhang <zhangchunyan@...as.ac.cn>
To: linux-riscv@...ts.infradead.org,
linux-mm@...ck.org,
linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Alexandre Ghiti <alex@...ti.fr>,
Andrew Morton <akpm@...ux-foundation.org>,
Deepak Gupta <debug@...osinc.com>,
Ved Shanbhogue <ved@...osinc.com>,
Peter Xu <peterx@...hat.com>,
Alexander Viro <viro@...iv.linux.org.uk>,
Christian Brauner <brauner@...nel.org>,
Arnd Bergmann <arnd@...db.de>,
Jan Kara <jack@...e.cz>,
Axel Rasmussen <axelrasmussen@...gle.com>,
Wei Xu <weixugc@...gle.com>,
David Hildenbrand <david@...hat.com>,
Chunyan Zhang <zhang.lyra@...il.com>
Subject: [PATCH v9 1/5] mm: softdirty: Add pte_soft_dirty_available()
Some platforms can customize the PTE soft dirty bit and make it unavailable
even if the architecture allows providing the PTE resource.
Signed-off-by: Chunyan Zhang <zhangchunyan@...as.ac.cn>
---
fs/proc/task_mmu.c | 12 +++++++++++-
include/linux/pgtable.h | 9 +++++++++
mm/debug_vm_pgtable.c | 9 +++++----
mm/huge_memory.c | 13 +++++++------
mm/internal.h | 2 +-
mm/mremap.c | 13 +++++++------
mm/userfaultfd.c | 12 ++++++------
7 files changed, 46 insertions(+), 24 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 29cca0e6d0ff..32ba2fb92975 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1058,7 +1058,7 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma)
* -Werror=unterminated-string-initialization warning
* with GCC 15
*/
- static const char mnemonics[BITS_PER_LONG][3] = {
+ static char mnemonics[BITS_PER_LONG][3] = {
/*
* In case if we meet a flag we don't know about.
*/
@@ -1129,6 +1129,11 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma)
[ilog2(VM_SEALED)] = "sl",
#endif
};
+#ifdef CONFIG_MEM_SOFT_DIRTY
+ if (!pte_soft_dirty_available())
+ mnemonics[ilog2(VM_SOFTDIRTY)][0] = 0;
+#endif
+
size_t i;
seq_puts(m, "VmFlags: ");
@@ -1531,6 +1536,8 @@ static inline bool pte_is_pinned(struct vm_area_struct *vma, unsigned long addr,
static inline void clear_soft_dirty(struct vm_area_struct *vma,
unsigned long addr, pte_t *pte)
{
+ if (!pte_soft_dirty_available())
+ return;
/*
* The soft-dirty tracker uses #PF-s to catch writes
* to pages, so write-protect the pte as well. See the
@@ -1566,6 +1573,9 @@ static inline void clear_soft_dirty_pmd(struct vm_area_struct *vma,
{
pmd_t old, pmd = *pmdp;
+ if (!pte_soft_dirty_available())
+ return;
+
if (pmd_present(pmd)) {
/* See comment in change_huge_pmd() */
old = pmdp_invalidate(vma, addr, pmdp);
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 4c035637eeb7..2a489647ac96 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -1538,6 +1538,15 @@ static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
#endif
#ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY
+
+/*
+ * Some platforms can customize the PTE soft dirty bit and make it unavailable
+ * even if the architecture allows providing the PTE resource.
+ */
+#ifndef pte_soft_dirty_available
+#define pte_soft_dirty_available() (true)
+#endif
+
#ifndef CONFIG_ARCH_ENABLE_THP_MIGRATION
static inline pmd_t pmd_swp_mksoft_dirty(pmd_t pmd)
{
diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index 830107b6dd08..98ed7e22ccec 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -690,7 +690,7 @@ static void __init pte_soft_dirty_tests(struct pgtable_debug_args *args)
{
pte_t pte = pfn_pte(args->fixed_pte_pfn, args->page_prot);
- if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY))
+ if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) || !pte_soft_dirty_available())
return;
pr_debug("Validating PTE soft dirty\n");
@@ -702,7 +702,7 @@ static void __init pte_swap_soft_dirty_tests(struct pgtable_debug_args *args)
{
pte_t pte;
- if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY))
+ if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) || !pte_soft_dirty_available())
return;
pr_debug("Validating PTE swap soft dirty\n");
@@ -718,7 +718,7 @@ static void __init pmd_soft_dirty_tests(struct pgtable_debug_args *args)
{
pmd_t pmd;
- if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY))
+ if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) || !pte_soft_dirty_available())
return;
if (!has_transparent_hugepage())
@@ -735,7 +735,8 @@ static void __init pmd_swap_soft_dirty_tests(struct pgtable_debug_args *args)
pmd_t pmd;
if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) ||
- !IS_ENABLED(CONFIG_ARCH_ENABLE_THP_MIGRATION))
+ !pte_soft_dirty_available() ||
+ !IS_ENABLED(CONFIG_ARCH_ENABLE_THP_MIGRATION))
return;
if (!has_transparent_hugepage())
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 9c38a95e9f09..2cf001b2e950 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2271,12 +2271,13 @@ static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
static pmd_t move_soft_dirty_pmd(pmd_t pmd)
{
-#ifdef CONFIG_MEM_SOFT_DIRTY
- if (unlikely(is_pmd_migration_entry(pmd)))
- pmd = pmd_swp_mksoft_dirty(pmd);
- else if (pmd_present(pmd))
- pmd = pmd_mksoft_dirty(pmd);
-#endif
+ if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && pte_soft_dirty_available()) {
+ if (unlikely(is_pmd_migration_entry(pmd)))
+ pmd = pmd_swp_mksoft_dirty(pmd);
+ else if (pmd_present(pmd))
+ pmd = pmd_mksoft_dirty(pmd);
+ }
+
return pmd;
}
diff --git a/mm/internal.h b/mm/internal.h
index 45b725c3dc03..8a5b20fac892 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1538,7 +1538,7 @@ static inline bool vma_soft_dirty_enabled(struct vm_area_struct *vma)
* VM_SOFTDIRTY is defined as 0x0, then !(vm_flags & VM_SOFTDIRTY)
* will be constantly true.
*/
- if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY))
+ if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) || !pte_soft_dirty_available())
return false;
/*
diff --git a/mm/mremap.c b/mm/mremap.c
index e618a706aff5..7c01320aea33 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -162,12 +162,13 @@ static pte_t move_soft_dirty_pte(pte_t pte)
* Set soft dirty bit so we can notice
* in userspace the ptes were moved.
*/
-#ifdef CONFIG_MEM_SOFT_DIRTY
- if (pte_present(pte))
- pte = pte_mksoft_dirty(pte);
- else if (is_swap_pte(pte))
- pte = pte_swp_mksoft_dirty(pte);
-#endif
+ if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && pte_soft_dirty_available()) {
+ if (pte_present(pte))
+ pte = pte_mksoft_dirty(pte);
+ else if (is_swap_pte(pte))
+ pte = pte_swp_mksoft_dirty(pte);
+ }
+
return pte;
}
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 45e6290e2e8b..0e07a983c513 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -1065,9 +1065,9 @@ static int move_present_pte(struct mm_struct *mm,
orig_dst_pte = folio_mk_pte(src_folio, dst_vma->vm_page_prot);
/* Set soft dirty bit so userspace can notice the pte was moved */
-#ifdef CONFIG_MEM_SOFT_DIRTY
- orig_dst_pte = pte_mksoft_dirty(orig_dst_pte);
-#endif
+ if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && pte_soft_dirty_available())
+ orig_dst_pte = pte_mksoft_dirty(orig_dst_pte);
+
if (pte_dirty(orig_src_pte))
orig_dst_pte = pte_mkdirty(orig_dst_pte);
orig_dst_pte = pte_mkwrite(orig_dst_pte, dst_vma);
@@ -1134,9 +1134,9 @@ static int move_swap_pte(struct mm_struct *mm, struct vm_area_struct *dst_vma,
}
orig_src_pte = ptep_get_and_clear(mm, src_addr, src_pte);
-#ifdef CONFIG_MEM_SOFT_DIRTY
- orig_src_pte = pte_swp_mksoft_dirty(orig_src_pte);
-#endif
+ if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && pte_soft_dirty_available())
+ orig_src_pte = pte_swp_mksoft_dirty(orig_src_pte);
+
set_pte_at(mm, dst_addr, dst_pte, orig_src_pte);
double_pt_unlock(dst_ptl, src_ptl);
--
2.34.1
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