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mm: softdirty: add pgtable_supports_soft_dirty() 

Patch series "mm: Add soft-dirty and uffd-wp support for RISC-V", v15.

This patchset adds support for Svrsw60t59b [1] extension which is ratified
now, also add soft dirty and userfaultfd write protect tracking for
RISC-V.

The patches 1 and 2 add macros to allow architectures to define their own
checks if the soft-dirty / uffd_wp PTE bits are available, in other words
for RISC-V, the Svrsw60t59b extension is supported on which device the
kernel is running.  Also patch1-2 are removing "ifdef
CONFIG_MEM_SOFT_DIRTY" "ifdef CONFIG_HAVE_ARCH_USERFAULTFD_WP" and "ifdef
CONFIG_PTE_MARKER_UFFD_WP" in favor of checks which if not overridden by
the architecture, no change in behavior is expected.

This patchset has been tested with kselftest mm suite in which soft-dirty,
madv_populate, test_unmerge_uffd_wp, and uffd-unit-tests run and pass, and
no regressions are observed in any of the other tests.


This patch (of 6):

Some platforms can customize the PTE PMD entry soft-dirty bit making it
unavailable even if the architecture provides the resource.

Add an API which architectures can define their specific implementations
to detect if soft-dirty bit is available on which device the kernel is
running.

This patch is removing "ifdef CONFIG_MEM_SOFT_DIRTY" in favor of
pgtable_supports_soft_dirty() checks that defaults to
IS_ENABLED(CONFIG_MEM_SOFT_DIRTY), if not overridden by the architecture,
no change in behavior is expected.

We make sure to never set VM_SOFTDIRTY if !pgtable_supports_soft_dirty(),
so we will never run into VM_SOFTDIRTY checks.

[lorenzo.stoakes@oracle.com: fix VMA selftests]
  Link: https://lkml.kernel.org/r/dac6ddfe-773a-43d5-8f69-021b9ca4d24b@lucifer.local
Link: https://lkml.kernel.org/r/20251113072806.795029-1-zhangchunyan@iscas.ac.cn
Link: https://lkml.kernel.org/r/20251113072806.795029-2-zhangchunyan@iscas.ac.cn
Link: https://github.com/riscv-non-isa/riscv-iommu/pull/543 [1]
Signed-off-by: Chunyan Zhang <zhangchunyan@iscas.ac.cn>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Conor Dooley <conor@kernel.org>
Cc: Deepak Gupta <debug@rivosinc.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Andrew Jones <ajones@ventanamicro.com>
Cc: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Chunyan Zhang 2025-11-13 15:28:01 +08:00 committed by Andrew Morton
parent d85b653f2c
commit 277a1ae387
12 changed files with 59 additions and 38 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
fs/proc/task_mmu.c
View File

@ -1584,8 +1584,6 @@ struct clear_refs_private {
enum clear_refs_types type;
};
#ifdef CONFIG_MEM_SOFT_DIRTY
static inline bool pte_is_pinned(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
{
struct folio *folio;
@ -1605,6 +1603,8 @@ 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 (!pgtable_supports_soft_dirty())
return;
/*
* The soft-dirty tracker uses #PF-s to catch writes
* to pages, so write-protect the pte as well. See the
@ -1630,19 +1630,16 @@ static inline void clear_soft_dirty(struct vm_area_struct *vma,
set_pte_at(vma->vm_mm, addr, pte, ptent);
}
}
#else
static inline void clear_soft_dirty(struct vm_area_struct *vma,
unsigned long addr, pte_t *pte)
{
}
#endif
#if defined(CONFIG_MEM_SOFT_DIRTY) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
#if defined(CONFIG_TRANSPARENT_HUGEPAGE)
static inline void clear_soft_dirty_pmd(struct vm_area_struct *vma,
unsigned long addr, pmd_t *pmdp)
{
pmd_t old, pmd = *pmdp;
if (!pgtable_supports_soft_dirty())
return;
if (pmd_present(pmd)) {
/* See comment in change_huge_pmd() */
old = pmdp_invalidate(vma, addr, pmdp);

3
include/linux/mm.h
View File

@ -859,6 +859,7 @@ static inline void vma_init(struct vm_area_struct *vma, struct mm_struct *mm)
static inline void vm_flags_init(struct vm_area_struct *vma,
vm_flags_t flags)
{
VM_WARN_ON_ONCE(!pgtable_supports_soft_dirty() && (flags & VM_SOFTDIRTY));
ACCESS_PRIVATE(vma, __vm_flags) = flags;
}
@ -870,6 +871,7 @@ static inline void vm_flags_init(struct vm_area_struct *vma,
static inline void vm_flags_reset(struct vm_area_struct *vma,
vm_flags_t flags)
{
VM_WARN_ON_ONCE(!pgtable_supports_soft_dirty() && (flags & VM_SOFTDIRTY));
vma_assert_write_locked(vma);
vm_flags_init(vma, flags);
}
@ -891,6 +893,7 @@ static inline void vm_flags_set(struct vm_area_struct *vma,
static inline void vm_flags_clear(struct vm_area_struct *vma,
vm_flags_t flags)
{
VM_WARN_ON_ONCE(!pgtable_supports_soft_dirty() && (flags & VM_SOFTDIRTY));
vma_start_write(vma);
ACCESS_PRIVATE(vma, __vm_flags) &= ~flags;
}

12
include/linux/pgtable.h
View File

@ -1553,6 +1553,18 @@ static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
#define arch_start_context_switch(prev) do {} while (0)
#endif
/*
* Some platforms can customize the PTE soft-dirty bit making it unavailable
* even if the architecture provides the resource.
* Adding this API allows architectures to add their own checks for the
* devices on which the kernel is running.
* Note: When overriding it, please make sure the CONFIG_MEM_SOFT_DIRTY
* is part of this macro.
*/
#ifndef pgtable_supports_soft_dirty
#define pgtable_supports_soft_dirty() IS_ENABLED(CONFIG_MEM_SOFT_DIRTY)
#endif
#ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY
#ifndef CONFIG_ARCH_ENABLE_THP_MIGRATION
static inline pmd_t pmd_swp_mksoft_dirty(pmd_t pmd)

10
mm/debug_vm_pgtable.c
View File

@ -704,7 +704,7 @@ 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 (!pgtable_supports_soft_dirty())
return;
pr_debug("Validating PTE soft dirty\n");
@ -717,7 +717,7 @@ static void __init pte_swap_soft_dirty_tests(struct pgtable_debug_args *args)
pte_t pte;
softleaf_t entry;
if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY))
if (!pgtable_supports_soft_dirty())
return;
pr_debug("Validating PTE swap soft dirty\n");
@ -734,7 +734,7 @@ static void __init pmd_soft_dirty_tests(struct pgtable_debug_args *args)
{
pmd_t pmd;
if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY))
if (!pgtable_supports_soft_dirty())
return;
if (!has_transparent_hugepage())
@ -750,8 +750,8 @@ static void __init pmd_leaf_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))
if (!pgtable_supports_soft_dirty() ||
!IS_ENABLED(CONFIG_ARCH_ENABLE_THP_MIGRATION))
return;
if (!has_transparent_hugepage())

13
mm/huge_memory.c
View File

@ -2427,12 +2427,13 @@ 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(pmd_is_migration_entry(pmd)))
pmd = pmd_swp_mksoft_dirty(pmd);
else if (pmd_present(pmd))
pmd = pmd_mksoft_dirty(pmd);
#endif
if (pgtable_supports_soft_dirty()) {
if (unlikely(pmd_is_migration_entry(pmd)))
pmd = pmd_swp_mksoft_dirty(pmd);
else if (pmd_present(pmd))
pmd = pmd_mksoft_dirty(pmd);
}
return pmd;
}

2
mm/internal.h
View File

@ -1554,7 +1554,7 @@ 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 (!pgtable_supports_soft_dirty())
return false;
/*

6
mm/mmap.c
View File

@ -1448,8 +1448,10 @@ static struct vm_area_struct *__install_special_mapping(
return ERR_PTR(-ENOMEM);
vma_set_range(vma, addr, addr + len, 0);
vm_flags_init(vma, (vm_flags | mm->def_flags |
VM_DONTEXPAND | VM_SOFTDIRTY) & ~VM_LOCKED_MASK);
vm_flags |= mm->def_flags | VM_DONTEXPAND;
if (pgtable_supports_soft_dirty())
vm_flags |= VM_SOFTDIRTY;
vm_flags_init(vma, vm_flags & ~VM_LOCKED_MASK);
vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
vma->vm_ops = ops;

13
mm/mremap.c
View File

@ -165,12 +165,13 @@ 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
pte = pte_swp_mksoft_dirty(pte);
#endif
if (pgtable_supports_soft_dirty()) {
if (pte_present(pte))
pte = pte_mksoft_dirty(pte);
else
pte = pte_swp_mksoft_dirty(pte);
}
return pte;
}

10
mm/userfaultfd.c
View File

@ -1119,9 +1119,8 @@ static long move_present_ptes(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 (pgtable_supports_soft_dirty())
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);
@ -1208,9 +1207,8 @@ 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 (pgtable_supports_soft_dirty())
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);

6
mm/vma.c
View File

@ -2559,7 +2559,8 @@ static void __mmap_complete(struct mmap_state *map, struct vm_area_struct *vma)
* then new mapped in-place (which must be aimed as
* a completely new data area).
*/
vm_flags_set(vma, VM_SOFTDIRTY);
if (pgtable_supports_soft_dirty())
vm_flags_set(vma, VM_SOFTDIRTY);
vma_set_page_prot(vma);
}
@ -2864,7 +2865,8 @@ int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma,
mm->data_vm += len >> PAGE_SHIFT;
if (vm_flags & VM_LOCKED)
mm->locked_vm += (len >> PAGE_SHIFT);
vm_flags_set(vma, VM_SOFTDIRTY);
if (pgtable_supports_soft_dirty())
vm_flags_set(vma, VM_SOFTDIRTY);
return 0;
mas_store_fail:

5
mm/vma_exec.c
View File

@ -107,6 +107,7 @@ int relocate_vma_down(struct vm_area_struct *vma, unsigned long shift)
int create_init_stack_vma(struct mm_struct *mm, struct vm_area_struct **vmap,
unsigned long *top_mem_p)
{
unsigned long flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
int err;
struct vm_area_struct *vma = vm_area_alloc(mm);
@ -137,7 +138,9 @@ int create_init_stack_vma(struct mm_struct *mm, struct vm_area_struct **vmap,
BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
vma->vm_end = STACK_TOP_MAX;
vma->vm_start = vma->vm_end - PAGE_SIZE;
vm_flags_init(vma, VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP);
if (pgtable_supports_soft_dirty())
flags |= VM_SOFTDIRTY;
vm_flags_init(vma, flags);
vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
err = insert_vm_struct(mm, vma);

2
tools/testing/vma/vma_internal.h
View File

@ -212,6 +212,8 @@ typedef __bitwise unsigned int vm_fault_t;
#define ASSERT_EXCLUSIVE_WRITER(x)
#define pgtable_supports_soft_dirty() 1
/**
* swap - swap values of @a and @b
* @a: first value