The patch titled
Subject: mm: pagewalk: add 'depth' parameter to pte_hole
has been added to the -mm tree. Its filename is
mm-pagewalk-add-depth-parameter-to-pte_hole.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-pagewalk-add-depth-parameter-to-pte_hole.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-pagewalk-add-depth-parameter-to-pte_hole.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
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------------------------------------------------------
From: Steven Price <steven.price@xxxxxxx>
Subject: mm: pagewalk: add 'depth' parameter to pte_hole
The pte_hole() callback is called at multiple levels of the page tables.
Code dumping the kernel page tables needs to know what at what depth the
missing entry is. Add this is an extra parameter to pte_hole(). When the
depth isn't know (e.g. processing a vma) then -1 is passed.
The depth that is reported is the actual level where the entry is missing
(ignoring any folding that is in place), i.e. any levels where
PTRS_PER_P?D is set to 1 are ignored.
Note that depth starts at 0 for a PGD so that PUD/PMD/PTE retain their
natural numbers as levels 2/3/4.
Link: http://lkml.kernel.org/r/20190731154603.41797-15-steven.price@xxxxxxx
Signed-off-by: Steven Price <steven.price@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/task_mmu.c | 4 ++--
include/linux/mm.h | 6 ++++--
mm/hmm.c | 2 +-
mm/migrate.c | 1 +
mm/mincore.c | 1 +
mm/pagewalk.c | 31 +++++++++++++++++++++++++------
6 files changed, 34 insertions(+), 11 deletions(-)
--- a/fs/proc/task_mmu.c~mm-pagewalk-add-depth-parameter-to-pte_hole
+++ a/fs/proc/task_mmu.c
@@ -504,7 +504,7 @@ static void smaps_account(struct mem_siz
#ifdef CONFIG_SHMEM
static int smaps_pte_hole(unsigned long addr, unsigned long end,
- struct mm_walk *walk)
+ __always_unused int depth, struct mm_walk *walk)
{
struct mem_size_stats *mss = walk->private;
@@ -1274,7 +1274,7 @@ static int add_to_pagemap(unsigned long
}
static int pagemap_pte_hole(unsigned long start, unsigned long end,
- struct mm_walk *walk)
+ __always_unused int depth, struct mm_walk *walk)
{
struct pagemapread *pm = walk->private;
unsigned long addr = start;
--- a/include/linux/mm.h~mm-pagewalk-add-depth-parameter-to-pte_hole
+++ a/include/linux/mm.h
@@ -1459,7 +1459,9 @@ void unmap_vmas(struct mmu_gather *tlb,
* pmd_trans_huge() pmds. They may simply choose to
* split_huge_page() instead of handling it explicitly.
* @pte_entry: if set, called for each non-empty PTE (lowest-level) entry
- * @pte_hole: if set, called for each hole at all levels
+ * @pte_hole: if set, called for each hole at all levels,
+ * depth is -1 if not known, 0:PGD, 1:P4D, 2:PUD, 3:PMD, 4:PTE
+ * any depths where PTRS_PER_P?D is equal to 1 are skipped
* @hugetlb_entry: if set, called for each hugetlb entry
* @test_walk: caller specific callback function to determine whether
* we walk over the current vma or not. Returning 0
@@ -1492,7 +1494,7 @@ struct mm_walk {
int (*pte_entry)(pte_t *pte, unsigned long addr,
unsigned long next, struct mm_walk *walk);
int (*pte_hole)(unsigned long addr, unsigned long next,
- struct mm_walk *walk);
+ int depth, struct mm_walk *walk);
int (*hugetlb_entry)(pte_t *pte, unsigned long hmask,
unsigned long addr, unsigned long next,
struct mm_walk *walk);
--- a/mm/hmm.c~mm-pagewalk-add-depth-parameter-to-pte_hole
+++ a/mm/hmm.c
@@ -433,7 +433,7 @@ static void hmm_range_need_fault(const s
}
static int hmm_vma_walk_hole(unsigned long addr, unsigned long end,
- struct mm_walk *walk)
+ __always_unused int depth, struct mm_walk *walk)
{
struct hmm_vma_walk *hmm_vma_walk = walk->private;
struct hmm_range *range = hmm_vma_walk->range;
--- a/mm/migrate.c~mm-pagewalk-add-depth-parameter-to-pte_hole
+++ a/mm/migrate.c
@@ -2132,6 +2132,7 @@ struct migrate_vma {
static int migrate_vma_collect_hole(unsigned long start,
unsigned long end,
+ __always_unused int depth,
struct mm_walk *walk)
{
struct migrate_vma *migrate = walk->private;
--- a/mm/mincore.c~mm-pagewalk-add-depth-parameter-to-pte_hole
+++ a/mm/mincore.c
@@ -112,6 +112,7 @@ static int __mincore_unmapped_range(unsi
}
static int mincore_unmapped_range(unsigned long addr, unsigned long end,
+ __always_unused int depth,
struct mm_walk *walk)
{
walk->private += __mincore_unmapped_range(addr, end,
--- a/mm/pagewalk.c~mm-pagewalk-add-depth-parameter-to-pte_hole
+++ a/mm/pagewalk.c
@@ -4,6 +4,22 @@
#include <linux/sched.h>
#include <linux/hugetlb.h>
+/*
+ * We want to know the real level where a entry is located ignoring any
+ * folding of levels which may be happening. For example if p4d is folded then
+ * a missing entry found at level 1 (p4d) is actually at level 0 (pgd).
+ */
+static int real_depth(int depth)
+{
+ if (depth == 3 && PTRS_PER_PMD == 1)
+ depth = 2;
+ if (depth == 2 && PTRS_PER_PUD == 1)
+ depth = 1;
+ if (depth == 1 && PTRS_PER_P4D == 1)
+ depth = 0;
+ return depth;
+}
+
static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
@@ -31,6 +47,7 @@ static int walk_pmd_range(pud_t *pud, un
pmd_t *pmd;
unsigned long next;
int err = 0;
+ int depth = real_depth(3);
if (walk->test_pmd) {
err = walk->test_pmd(addr, end, pmd_offset(pud, 0UL), walk);
@@ -46,7 +63,7 @@ again:
next = pmd_addr_end(addr, end);
if (pmd_none(*pmd)) {
if (walk->pte_hole)
- err = walk->pte_hole(addr, next, walk);
+ err = walk->pte_hole(addr, next, depth, walk);
if (err)
break;
continue;
@@ -89,6 +106,7 @@ static int walk_pud_range(p4d_t *p4d, un
pud_t *pud;
unsigned long next;
int err = 0;
+ int depth = real_depth(2);
if (walk->test_pud) {
err = walk->test_pud(addr, end, pud_offset(p4d, 0UL), walk);
@@ -104,7 +122,7 @@ static int walk_pud_range(p4d_t *p4d, un
next = pud_addr_end(addr, end);
if (pud_none(*pud)) {
if (walk->pte_hole)
- err = walk->pte_hole(addr, next, walk);
+ err = walk->pte_hole(addr, next, depth, walk);
if (err)
break;
continue;
@@ -139,6 +157,7 @@ static int walk_p4d_range(pgd_t *pgd, un
p4d_t *p4d;
unsigned long next;
int err = 0;
+ int depth = real_depth(1);
if (walk->test_p4d) {
err = walk->test_p4d(addr, end, p4d_offset(pgd, 0UL), walk);
@@ -153,7 +172,7 @@ static int walk_p4d_range(pgd_t *pgd, un
next = p4d_addr_end(addr, end);
if (p4d_none_or_clear_bad(p4d)) {
if (walk->pte_hole)
- err = walk->pte_hole(addr, next, walk);
+ err = walk->pte_hole(addr, next, depth, walk);
if (err)
break;
continue;
@@ -184,7 +203,7 @@ static int walk_pgd_range(unsigned long
next = pgd_addr_end(addr, end);
if (pgd_none_or_clear_bad(pgd)) {
if (walk->pte_hole)
- err = walk->pte_hole(addr, next, walk);
+ err = walk->pte_hole(addr, next, 0, walk);
if (err)
break;
continue;
@@ -230,7 +249,7 @@ static int walk_hugetlb_range(unsigned l
if (pte)
err = walk->hugetlb_entry(pte, hmask, addr, next, walk);
else if (walk->pte_hole)
- err = walk->pte_hole(addr, next, walk);
+ err = walk->pte_hole(addr, next, -1, walk);
if (err)
break;
@@ -273,7 +292,7 @@ static int walk_page_test(unsigned long
if (vma->vm_flags & VM_PFNMAP) {
int err = 1;
if (walk->pte_hole)
- err = walk->pte_hole(start, end, walk);
+ err = walk->pte_hole(start, end, -1, walk);
return err ? err : 1;
}
return 0;
_
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-add-test_pd-callbacks.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
x86-mm-convert-ptdump_walk_pgd_level_core-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
