The patch titled
Subject: mm: pagewalk: allow walking without vma
has been added to the -mm tree. Its filename is
mm-pagewalk-allow-walking-without-vma.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-pagewalk-allow-walking-without-vma.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-pagewalk-allow-walking-without-vma.patch
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------------------------------------------------------
From: Steven Price <steven.price@xxxxxxx>
Subject: mm: pagewalk: allow walking without vma
Since 48684a65b4e3: "mm: pagewalk: fix misbehavior of walk_page_range for
vma(VM_PFNMAP)", page_table_walk() will report any kernel area as a hole,
because it lacks a vma.
This means each arch has re-implemented page table walking when needed,
for example in the per-arch ptdump walker.
Remove the requirement to have a vma in the generic code and add a new
function walk_page_range_novma() which ignores the VMAs and simply walks
the page tables.
Link: http://lkml.kernel.org/r/20191218162402.45610-13-steven.price@xxxxxxx
Signed-off-by: Steven Price <steven.price@xxxxxxx>
Cc: Albert Ou <aou@xxxxxxxxxxxxxxxxx>
Cc: Alexandre Ghiti <alex@xxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: James Hogan <jhogan@xxxxxxxxxx>
Cc: James Morse <james.morse@xxxxxxx>
Cc: Jerome Glisse <jglisse@xxxxxxxxxx>
Cc: "Liang, Kan" <kan.liang@xxxxxxxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxx>
Cc: Paul Burton <paul.burton@xxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Paul Walmsley <paul.walmsley@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Cc: Vineet Gupta <vgupta@xxxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Zong Li <zong.li@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/pagewalk.h | 5 ++++
mm/pagewalk.c | 40 +++++++++++++++++++++++++++++--------
2 files changed, 37 insertions(+), 8 deletions(-)
--- a/include/linux/pagewalk.h~mm-pagewalk-allow-walking-without-vma
+++ a/include/linux/pagewalk.h
@@ -73,6 +73,7 @@ enum page_walk_action {
* @mm: mm_struct representing the target process of page table walk
* @vma: vma currently walked (NULL if walking outside vmas)
* @action: next action to perform (see enum page_walk_action)
+ * @no_vma: walk ignoring vmas (vma will always be NULL)
* @private: private data for callbacks' usage
*
* (see the comment on walk_page_range() for more details)
@@ -82,12 +83,16 @@ struct mm_walk {
struct mm_struct *mm;
struct vm_area_struct *vma;
enum page_walk_action action;
+ bool no_vma;
void *private;
};
int walk_page_range(struct mm_struct *mm, unsigned long start,
unsigned long end, const struct mm_walk_ops *ops,
void *private);
+int walk_page_range_novma(struct mm_struct *mm, unsigned long start,
+ unsigned long end, const struct mm_walk_ops *ops,
+ void *private);
int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
void *private);
int walk_page_mapping(struct address_space *mapping, pgoff_t first_index,
--- a/mm/pagewalk.c~mm-pagewalk-allow-walking-without-vma
+++ a/mm/pagewalk.c
@@ -39,7 +39,7 @@ static int walk_pmd_range(pud_t *pud, un
do {
again:
next = pmd_addr_end(addr, end);
- if (pmd_none(*pmd) || !walk->vma) {
+ if (pmd_none(*pmd) || (!walk->vma && !walk->no_vma)) {
if (ops->pte_hole)
err = ops->pte_hole(addr, next, walk);
if (err)
@@ -65,13 +65,16 @@ again:
* Check this here so we only break down trans_huge
* pages when we _need_ to
*/
- if (walk->action == ACTION_CONTINUE ||
+ if ((!walk->vma && (pmd_leaf(*pmd) || !pmd_present(*pmd))) ||
+ walk->action == ACTION_CONTINUE ||
!(ops->pte_entry))
continue;
- split_huge_pmd(walk->vma, pmd, addr);
- if (pmd_trans_unstable(pmd))
- goto again;
+ if (walk->vma) {
+ split_huge_pmd(walk->vma, pmd, addr);
+ if (pmd_trans_unstable(pmd))
+ goto again;
+ }
err = walk_pte_range(pmd, addr, next, walk);
if (err)
@@ -93,7 +96,7 @@ static int walk_pud_range(p4d_t *p4d, un
do {
again:
next = pud_addr_end(addr, end);
- if (pud_none(*pud) || !walk->vma) {
+ if (pud_none(*pud) || (!walk->vma && !walk->no_vma)) {
if (ops->pte_hole)
err = ops->pte_hole(addr, next, walk);
if (err)
@@ -111,11 +114,13 @@ static int walk_pud_range(p4d_t *p4d, un
if (walk->action == ACTION_AGAIN)
goto again;
- if (walk->action == ACTION_CONTINUE ||
+ if ((!walk->vma && (pud_leaf(*pud) || !pud_present(*pud))) ||
+ walk->action == ACTION_CONTINUE ||
!(ops->pmd_entry || ops->pte_entry))
continue;
- split_huge_pud(walk->vma, pud, addr);
+ if (walk->vma)
+ split_huge_pud(walk->vma, pud, addr);
if (pud_none(*pud))
goto again;
@@ -389,6 +394,25 @@ int walk_page_range(struct mm_struct *mm
return err;
}
+int walk_page_range_novma(struct mm_struct *mm, unsigned long start,
+ unsigned long end, const struct mm_walk_ops *ops,
+ void *private)
+{
+ struct mm_walk walk = {
+ .ops = ops,
+ .mm = mm,
+ .private = private,
+ .no_vma = true
+ };
+
+ if (start >= end || !walk.mm)
+ return -EINVAL;
+
+ lockdep_assert_held(&walk.mm->mmap_sem);
+
+ return __walk_page_range(start, end, &walk);
+}
+
int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
void *private)
{
_
Patches currently in -mm which might be from steven.price@xxxxxxx are
mm-add-generic-pd_leaf-macros.patch
arc-mm-add-pd_leaf-definitions.patch
arm-mm-add-pd_leaf-definitions.patch
arm64-mm-add-pd_leaf-definitions.patch
mips-mm-add-pd_leaf-definitions.patch
powerpc-mm-add-pd_leaf-definitions.patch
riscv-mm-add-pd_leaf-definitions.patch
s390-mm-add-pd_leaf-definitions.patch
sparc-mm-add-pd_leaf-definitions.patch
x86-mm-add-pd_leaf-definitions.patch
mm-pagewalk-add-p4d_entry-and-pgd_entry.patch
mm-pagewalk-allow-walking-without-vma.patch
mm-pagewalk-dont-lock-ptes-for-walk_page_range_novma.patch
mm-pagewalk-fix-termination-condition-in-walk_pte_range.patch
mm-pagewalk-add-depth-parameter-to-pte_hole.patch
x86-mm-point-to-struct-seq_file-from-struct-pg_state.patch
x86-mmefi-convert-ptdump_walk_pgd_level-to-take-a-mm_struct.patch
x86-mm-convert-ptdump_walk_pgd_level_debugfs-to-take-an-mm_struct.patch
mm-add-generic-ptdump.patch
x86-mm-convert-dump_pagetables-to-use-walk_page_range.patch
arm64-mm-convert-mm-dumpc-to-use-walk_page_range.patch
arm64-mm-display-non-present-entries-in-ptdump.patch
mm-ptdump-reduce-level-numbers-by-1-in-note_page.patch
