The patch titled
Subject: mm/memory.c: add apply_to_existing_page_range() helper
has been added to the -mm tree. Its filename is
mm-add-apply_to_existing_pages-helper.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-add-apply_to_existing_pages-helper.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-add-apply_to_existing_pages-helper.patch
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------------------------------------------------------
From: Daniel Axtens <dja@xxxxxxxxxx>
Subject: mm/memory.c: add apply_to_existing_page_range() helper
apply_to_page_range() takes an address range, and if any parts of it are
not covered by the existing page table hierarchy, it allocates memory to
fill them in.
In some use cases, this is not what we want - we want to be able to
operate exclusively on PTEs that are already in the tables.
Add apply_to_existing_page_range() for this. Adjust the walker functions
for apply_to_page_range to take 'create', which switches them between the
old and new modes.
This will be used in KASAN vmalloc.
Link: http://lkml.kernel.org/r/20191205140407.1874-1-dja@xxxxxxxxxx
Signed-off-by: Daniel Axtens <dja@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Daniel Axtens <dja@xxxxxxxxxx>
Cc: Qian Cai <cai@xxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm.h | 3
mm/memory.c | 131 +++++++++++++++++++++++++++++++------------
2 files changed, 99 insertions(+), 35 deletions(-)
--- a/include/linux/mm.h~mm-add-apply_to_existing_pages-helper
+++ a/include/linux/mm.h
@@ -2621,6 +2621,9 @@ static inline int vm_fault_to_errno(vm_f
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_pages(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);
--- a/mm/memory.c~mm-add-apply_to_existing_pages-helper
+++ a/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();
@@ -2052,62 +2060,83 @@ static int apply_to_pte_range(struct mm_
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;
}
@@ -2130,7 +2159,7 @@ int apply_to_page_range(struct mm_struct
pgd = pgd_offset(mm, addr);
do {
next = pgd_addr_end(addr, end);
- err = apply_to_p4d_range(mm, pgd, addr, next, fn, data);
+ err = apply_to_p4d_range(mm, pgd, addr, next, fn, data, true);
if (err)
break;
} while (pgd++, addr = next, addr != end);
@@ -2140,6 +2169,38 @@ int apply_to_page_range(struct mm_struct
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_pages(struct mm_struct *mm, unsigned long addr,
+ unsigned long size, pte_fn_t fn, void *data)
+{
+ pgd_t *pgd;
+ unsigned long next;
+ unsigned long end = addr + size;
+ int err = 0;
+
+ if (WARN_ON(addr >= end))
+ return -EINVAL;
+
+ pgd = pgd_offset(mm, addr);
+ do {
+ next = pgd_addr_end(addr, end);
+ if (pgd_none_or_clear_bad(pgd))
+ continue;
+ err = apply_to_p4d_range(mm, pgd, addr, next, fn, data, false);
+ if (err)
+ break;
+ } while (pgd++, addr = next, addr != end);
+
+ return err;
+}
+EXPORT_SYMBOL_GPL(apply_to_existing_pages);
+
+/*
* handle_pte_fault chooses page fault handler according to an entry which was
* read non-atomically. Before making any commitment, on those architectures
* or configurations (e.g. i386 with PAE) which might give a mix of unmatched
_
Patches currently in -mm which might be from dja@xxxxxxxxxx are
mm-add-apply_to_existing_pages-helper.patch
kasan-use-apply_to_existing_pages-for-releasing-vmalloc-shadow.patch
kasan-dont-assume-percpu-shadow-allocations-will-succeed.patch
