diff --git a/include/linux/mm.h b/include/linux/mm.h
index c97ea3b694e65b5b6b48d861d9b98ad388fae6f4..80a9162b406c26c702f15e264e0bd3083cd4636d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2621,6 +2621,9 @@ static inline int vm_fault_to_errno(vm_fault_t vm_fault, int foll_flags)
typedef int (*pte_fn_t)(pte_t *pte, unsigned long addr, void *data);
extern int apply_to_page_range(struct mm_struct *mm, unsigned long address,
unsigned long size, pte_fn_t fn, void *data);
+extern int apply_to_existing_page_range(struct mm_struct *mm,
+ unsigned long address, unsigned long size,
+ pte_fn_t fn, void *data);
#ifdef CONFIG_PAGE_POISONING
extern bool page_poisoning_enabled(void);
diff --git a/mm/memory.c b/mm/memory.c
index 606da187d1de904c226d3d53f56d696ab3d8964a..45442d9a4f525f271e00f395f02f059b25741d72 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2021,26 +2021,34 @@ EXPORT_SYMBOL(vm_iomap_memory);
static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
unsigned long addr, unsigned long end,
- pte_fn_t fn, void *data)
+ pte_fn_t fn, void *data, bool create)
{
pte_t *pte;
- int err;
+ int err = 0;
spinlock_t *uninitialized_var(ptl);
- pte = (mm == &init_mm) ?
- pte_alloc_kernel(pmd, addr) :
- pte_alloc_map_lock(mm, pmd, addr, &ptl);
- if (!pte)
- return -ENOMEM;
+ if (create) {
+ pte = (mm == &init_mm) ?
+ pte_alloc_kernel(pmd, addr) :
+ pte_alloc_map_lock(mm, pmd, addr, &ptl);
+ if (!pte)
+ return -ENOMEM;
+ } else {
+ pte = (mm == &init_mm) ?
+ pte_offset_kernel(pmd, addr) :
+ pte_offset_map_lock(mm, pmd, addr, &ptl);
+ }
BUG_ON(pmd_huge(*pmd));
arch_enter_lazy_mmu_mode();
do {
- err = fn(pte++, addr, data);
- if (err)
- break;
+ if (create || !pte_none(*pte)) {
+ err = fn(pte++, addr, data);
+ if (err)
+ break;
+ }
} while (addr += PAGE_SIZE, addr != end);
arch_leave_lazy_mmu_mode();
@@ -2052,77 +2060,95 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
unsigned long addr, unsigned long end,
- pte_fn_t fn, void *data)
+ pte_fn_t fn, void *data, bool create)
{
pmd_t *pmd;
unsigned long next;
- int err;
+ int err = 0;
BUG_ON(pud_huge(*pud));
- pmd = pmd_alloc(mm, pud, addr);
- if (!pmd)
- return -ENOMEM;
+ if (create) {
+ pmd = pmd_alloc(mm, pud, addr);
+ if (!pmd)
+ return -ENOMEM;
+ } else {
+ pmd = pmd_offset(pud, addr);
+ }
do {
next = pmd_addr_end(addr, end);
- err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
- if (err)
- break;
+ if (create || !pmd_none_or_clear_bad(pmd)) {
+ err = apply_to_pte_range(mm, pmd, addr, next, fn, data,
+ create);
+ if (err)
+ break;
+ }
} while (pmd++, addr = next, addr != end);
return err;
}
static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
unsigned long addr, unsigned long end,
- pte_fn_t fn, void *data)
+ pte_fn_t fn, void *data, bool create)
{
pud_t *pud;
unsigned long next;
- int err;
+ int err = 0;
- pud = pud_alloc(mm, p4d, addr);
- if (!pud)
- return -ENOMEM;
+ if (create) {
+ pud = pud_alloc(mm, p4d, addr);
+ if (!pud)
+ return -ENOMEM;
+ } else {
+ pud = pud_offset(p4d, addr);
+ }
do {
next = pud_addr_end(addr, end);
- err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
- if (err)
- break;
+ if (create || !pud_none_or_clear_bad(pud)) {
+ err = apply_to_pmd_range(mm, pud, addr, next, fn, data,
+ create);
+ if (err)
+ break;
+ }
} while (pud++, addr = next, addr != end);
return err;
}
static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
unsigned long addr, unsigned long end,
- pte_fn_t fn, void *data)
+ pte_fn_t fn, void *data, bool create)
{
p4d_t *p4d;
unsigned long next;
- int err;
+ int err = 0;
- p4d = p4d_alloc(mm, pgd, addr);
- if (!p4d)
- return -ENOMEM;
+ if (create) {
+ p4d = p4d_alloc(mm, pgd, addr);
+ if (!p4d)
+ return -ENOMEM;
+ } else {
+ p4d = p4d_offset(pgd, addr);
+ }
do {
next = p4d_addr_end(addr, end);
- err = apply_to_pud_range(mm, p4d, addr, next, fn, data);
- if (err)
- break;
+ if (create || !p4d_none_or_clear_bad(p4d)) {
+ err = apply_to_pud_range(mm, p4d, addr, next, fn, data,
+ create);
+ if (err)
+ break;
+ }
} while (p4d++, addr = next, addr != end);
return err;
}
-/*
- * Scan a region of virtual memory, filling in page tables as necessary
- * and calling a provided function on each leaf page table.
- */
-int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
- unsigned long size, pte_fn_t fn, void *data)
+static int __apply_to_page_range(struct mm_struct *mm, unsigned long addr,
+ unsigned long size, pte_fn_t fn,
+ void *data, bool create)
{
pgd_t *pgd;
unsigned long next;
unsigned long end = addr + size;
- int err;
+ int err = 0;
if (WARN_ON(addr >= end))
return -EINVAL;
@@ -2130,15 +2156,41 @@ int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
pgd = pgd_offset(mm, addr);
do {
next = pgd_addr_end(addr, end);
- err = apply_to_p4d_range(mm, pgd, addr, next, fn, data);
+ if (!create && pgd_none_or_clear_bad(pgd))
+ continue;
+ err = apply_to_p4d_range(mm, pgd, addr, next, fn, data, create);
if (err)
break;
} while (pgd++, addr = next, addr != end);
return err;
}
+
+/*
+ * Scan a region of virtual memory, filling in page tables as necessary
+ * and calling a provided function on each leaf page table.
+ */
+int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
+ unsigned long size, pte_fn_t fn, void *data)
+{
+ return __apply_to_page_range(mm, addr, size, fn, data, true);
+}
EXPORT_SYMBOL_GPL(apply_to_page_range);
+/*
+ * Scan a region of virtual memory, calling a provided function on
+ * each leaf page table where it exists.
+ *
+ * Unlike apply_to_page_range, this does _not_ fill in page tables
+ * where they are absent.
+ */
+int apply_to_existing_page_range(struct mm_struct *mm, unsigned long addr,
+ unsigned long size, pte_fn_t fn, void *data)
+{
+ return __apply_to_page_range(mm, addr, size, fn, data, false);
+}
+EXPORT_SYMBOL_GPL(apply_to_existing_page_range);
+
/*
* handle_pte_fault chooses page fault handler according to an entry which was
* read non-atomically. Before making any commitment, on those architectures