[PATCH 03/10] mm: pagewalk: have generic code keep track of VMA
From: Dave Hansen
Date: Mon Jun 02 2014 - 17:36:56 EST
From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
7 out of 9 of the page walkers need the VMA and pass it in some
way through mm_walk->private. Let's add it in the page walker
infrastructure.
This will increase the number of find_vma() calls, but the VMA
cache should help us out pretty nicely here. This is also quite
easy to optimize if this turns out to be an issue by skipping the
find_vma() call if 'addr' is still within our current
mm_walk->vma.
/proc/$pid/numa_map:
/proc/$pid/smaps:
lots of stuff including vma (vma is a drop in the bucket)
in a struct
/proc/$pid/clear_refs:
passes vma plus an enum in a struct
/proc/$pid/pagemap:
openrisc:
no VMA
MADV_WILLNEED:
walk->private is set to vma
cgroup precharge:
walk->private is set to vma
cgroup move charge:
walk->private is set to vma
powerpc subpages:
walk->private is set to vma
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
---
b/arch/powerpc/mm/subpage-prot.c | 3 --
b/fs/proc/task_mmu.c | 25 ++++++---------------
b/include/linux/mm.h | 1
b/mm/madvise.c | 3 --
b/mm/memcontrol.c | 4 +--
b/mm/pagewalk.c | 45 ++++++++++++++++++++++++++++++++++-----
6 files changed, 52 insertions(+), 29 deletions(-)
diff -puN arch/powerpc/mm/subpage-prot.c~page-walker-pass-vma arch/powerpc/mm/subpage-prot.c
--- a/arch/powerpc/mm/subpage-prot.c~page-walker-pass-vma 2014-06-02 14:20:19.524817706 -0700
+++ b/arch/powerpc/mm/subpage-prot.c 2014-06-02 14:20:19.536818243 -0700
@@ -134,7 +134,7 @@ static void subpage_prot_clear(unsigned
static int subpage_walk_pmd_entry(pmd_t *pmd, unsigned long addr,
unsigned long end, struct mm_walk *walk)
{
- struct vm_area_struct *vma = walk->private;
+ struct vm_area_struct *vma = walk->vma;
split_huge_page_pmd(vma, addr, pmd);
return 0;
}
@@ -163,7 +163,6 @@ static void subpage_mark_vma_nohuge(stru
if (vma->vm_start >= (addr + len))
break;
vma->vm_flags |= VM_NOHUGEPAGE;
- subpage_proto_walk.private = vma;
walk_page_range(vma->vm_start, vma->vm_end,
&subpage_proto_walk);
vma = vma->vm_next;
diff -puN fs/proc/task_mmu.c~page-walker-pass-vma fs/proc/task_mmu.c
--- a/fs/proc/task_mmu.c~page-walker-pass-vma 2014-06-02 14:20:19.526817794 -0700
+++ b/fs/proc/task_mmu.c 2014-06-02 14:20:19.537818287 -0700
@@ -424,7 +424,6 @@ const struct file_operations proc_tid_ma
#ifdef CONFIG_PROC_PAGE_MONITOR
struct mem_size_stats {
- struct vm_area_struct *vma;
unsigned long resident;
unsigned long shared_clean;
unsigned long shared_dirty;
@@ -443,7 +442,7 @@ static void smaps_pte_entry(pte_t ptent,
unsigned long ptent_size, struct mm_walk *walk)
{
struct mem_size_stats *mss = walk->private;
- struct vm_area_struct *vma = mss->vma;
+ struct vm_area_struct *vma = walk->vma;
pgoff_t pgoff = linear_page_index(vma, addr);
struct page *page = NULL;
int mapcount;
@@ -495,7 +494,7 @@ static int smaps_pte_range(pmd_t *pmd, u
struct mm_walk *walk)
{
struct mem_size_stats *mss = walk->private;
- struct vm_area_struct *vma = mss->vma;
+ struct vm_area_struct *vma = walk->vma;
pte_t *pte;
spinlock_t *ptl;
@@ -588,7 +587,6 @@ static int show_smap(struct seq_file *m,
};
memset(&mss, 0, sizeof mss);
- mss.vma = vma;
/* mmap_sem is held in m_start */
if (vma->vm_mm)
walk_page_range(vma->vm_start, vma->vm_end, &smaps_walk);
@@ -712,7 +710,6 @@ enum clear_refs_types {
};
struct clear_refs_private {
- struct vm_area_struct *vma;
enum clear_refs_types type;
};
@@ -748,7 +745,7 @@ static int clear_refs_pte_range(pmd_t *p
unsigned long end, struct mm_walk *walk)
{
struct clear_refs_private *cp = walk->private;
- struct vm_area_struct *vma = cp->vma;
+ struct vm_area_struct *vma = walk->vma;
pte_t *pte, ptent;
spinlock_t *ptl;
struct page *page;
@@ -828,7 +825,6 @@ static ssize_t clear_refs_write(struct f
if (type == CLEAR_REFS_SOFT_DIRTY)
mmu_notifier_invalidate_range_start(mm, 0, -1);
for (vma = mm->mmap; vma; vma = vma->vm_next) {
- cp.vma = vma;
/*
* Writing 1 to /proc/pid/clear_refs affects all pages.
*
@@ -1073,15 +1069,11 @@ static int pagemap_hugetlb_range(pte_t *
struct mm_walk *walk)
{
struct pagemapread *pm = walk->private;
- struct vm_area_struct *vma;
int err = 0;
int flags2;
pagemap_entry_t pme;
- vma = find_vma(walk->mm, addr);
- WARN_ON_ONCE(!vma);
-
- if (vma && (vma->vm_flags & VM_SOFTDIRTY))
+ if (walk->vma && (walk->vma->vm_flags & VM_SOFTDIRTY))
flags2 = __PM_SOFT_DIRTY;
else
flags2 = 0;
@@ -1241,7 +1233,6 @@ const struct file_operations proc_pagema
#ifdef CONFIG_NUMA
struct numa_maps {
- struct vm_area_struct *vma;
unsigned long pages;
unsigned long anon;
unsigned long active;
@@ -1317,11 +1308,11 @@ static int gather_pte_stats(pmd_t *pmd,
md = walk->private;
- if (pmd_trans_huge_lock(pmd, md->vma, &ptl) == 1) {
+ if (pmd_trans_huge_lock(pmd, walk->vma, &ptl) == 1) {
pte_t huge_pte = *(pte_t *)pmd;
struct page *page;
- page = can_gather_numa_stats(huge_pte, md->vma, addr);
+ page = can_gather_numa_stats(huge_pte, walk->vma, addr);
if (page)
gather_stats(page, md, pte_dirty(huge_pte),
HPAGE_PMD_SIZE/PAGE_SIZE);
@@ -1333,7 +1324,7 @@ static int gather_pte_stats(pmd_t *pmd,
return 0;
orig_pte = pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
do {
- struct page *page = can_gather_numa_stats(*pte, md->vma, addr);
+ struct page *page = can_gather_numa_stats(*pte, walk->vma, addr);
if (!page)
continue;
gather_stats(page, md, pte_dirty(*pte), 1);
@@ -1392,8 +1383,6 @@ static int show_numa_map(struct seq_file
/* Ensure we start with an empty set of numa_maps statistics. */
memset(md, 0, sizeof(*md));
- md->vma = vma;
-
walk.hugetlb_entry = gather_hugetbl_stats;
walk.pmd_entry = gather_pte_stats;
walk.private = md;
diff -puN include/linux/mm.h~page-walker-pass-vma include/linux/mm.h
--- a/include/linux/mm.h~page-walker-pass-vma 2014-06-02 14:20:19.528817884 -0700
+++ b/include/linux/mm.h 2014-06-02 14:20:19.538818332 -0700
@@ -1118,6 +1118,7 @@ struct mm_walk {
unsigned long addr, unsigned long next,
struct mm_walk *walk);
struct mm_struct *mm;
+ struct vm_area_struct *vma;
void *private;
};
diff -puN mm/madvise.c~page-walker-pass-vma mm/madvise.c
--- a/mm/madvise.c~page-walker-pass-vma 2014-06-02 14:20:19.529817929 -0700
+++ b/mm/madvise.c 2014-06-02 14:20:19.539818378 -0700
@@ -139,7 +139,7 @@ static int swapin_walk_pmd_entry(pmd_t *
unsigned long end, struct mm_walk *walk)
{
pte_t *orig_pte;
- struct vm_area_struct *vma = walk->private;
+ struct vm_area_struct *vma = walk->vma;
unsigned long index;
if (pmd_none_or_trans_huge_or_clear_bad(pmd))
@@ -176,7 +176,6 @@ static void force_swapin_readahead(struc
struct mm_walk walk = {
.mm = vma->vm_mm,
.pmd_entry = swapin_walk_pmd_entry,
- .private = vma,
};
walk_page_range(start, end, &walk);
diff -puN mm/memcontrol.c~page-walker-pass-vma mm/memcontrol.c
--- a/mm/memcontrol.c~page-walker-pass-vma 2014-06-02 14:20:19.532818064 -0700
+++ b/mm/memcontrol.c 2014-06-02 14:20:19.541818468 -0700
@@ -6786,7 +6786,7 @@ static int mem_cgroup_count_precharge_pt
unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
- struct vm_area_struct *vma = walk->private;
+ struct vm_area_struct *vma = walk->vma;
pte_t *pte;
spinlock_t *ptl;
@@ -6962,7 +6962,7 @@ static int mem_cgroup_move_charge_pte_ra
struct mm_walk *walk)
{
int ret = 0;
- struct vm_area_struct *vma = walk->private;
+ struct vm_area_struct *vma = walk->vma;
pte_t *pte;
spinlock_t *ptl;
enum mc_target_type target_type;
diff -puN mm/pagewalk.c~page-walker-pass-vma mm/pagewalk.c
--- a/mm/pagewalk.c~page-walker-pass-vma 2014-06-02 14:20:19.533818109 -0700
+++ b/mm/pagewalk.c 2014-06-02 14:20:19.542818513 -0700
@@ -3,6 +3,38 @@
#include <linux/sched.h>
#include <linux/hugetlb.h>
+
+/*
+ * The VMA which applies to the current place in the
+ * page walk is tracked in walk->vma. If there is
+ * no VMA covering the current area (when in a pte_hole)
+ * walk->vma will be NULL.
+ *
+ * If the area bing walked is covered by more than one
+ * VMA, then the first one will be set in walk->vma.
+ * Additional VMAs can be found by walking the VMA sibling
+ * list, or by calling this function or find_vma() directly.
+ *
+ * In a situation where the area being walked is not
+ * entirely covered by a VMA, the _first_ VMA which covers
+ * part of the area will be set in walk->vma.
+ */
+static void walk_update_vma(unsigned long addr, unsigned long end,
+ struct mm_walk *walk)
+{
+ struct vm_area_struct *new_vma = find_vma(walk->mm, addr);
+
+ /*
+ * find_vma() is not exact and returns the next VMA
+ * ending after addr. The vma we found may be outside
+ * the range which we are walking, so clear it if so.
+ */
+ if (new_vma && new_vma->vm_start >= end)
+ new_vma = NULL;
+
+ walk->vma = new_vma;
+}
+
static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
@@ -15,6 +47,7 @@ static int walk_pte_range(pmd_t *pmd, un
if (err)
break;
addr += PAGE_SIZE;
+ walk_update_vma(addr, addr + PAGE_SIZE, walk);
if (addr == end)
break;
pte++;
@@ -35,6 +68,7 @@ static int walk_pmd_range(pud_t *pud, un
do {
again:
next = pmd_addr_end(addr, end);
+ walk_update_vma(addr, next, walk);
if (pmd_none(*pmd)) {
if (walk->pte_hole)
err = walk->pte_hole(addr, next, walk);
@@ -79,6 +113,7 @@ static int walk_pud_range(pgd_t *pgd, un
pud = pud_offset(pgd, addr);
do {
next = pud_addr_end(addr, end);
+ walk_update_vma(addr, next, walk);
if (pud_none_or_clear_bad(pud)) {
if (walk->pte_hole)
err = walk->pte_hole(addr, next, walk);
@@ -105,10 +140,10 @@ static unsigned long hugetlb_entry_end(s
return boundary < end ? boundary : end;
}
-static int walk_hugetlb_range(struct vm_area_struct *vma,
- unsigned long addr, unsigned long end,
+static int walk_hugetlb_range(unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
+ struct vm_area_struct *vma = walk->vma;
struct hstate *h = hstate_vma(vma);
unsigned long next;
unsigned long hmask = huge_page_mask(h);
@@ -187,14 +222,14 @@ int walk_page_range(unsigned long addr,
struct vm_area_struct *vma = NULL;
next = pgd_addr_end(addr, end);
-
+ walk_update_vma(addr, next, walk);
/*
* This function was not intended to be vma based.
* But there are vma special cases to be handled:
* - hugetlb vma's
* - VM_PFNMAP vma's
*/
- vma = find_vma(walk->mm, addr);
+ vma = walk->vma;
if (vma && (vma->vm_start <= addr)) {
/*
* There are no page structures backing a VM_PFNMAP
@@ -219,7 +254,7 @@ int walk_page_range(unsigned long addr,
* so walk through hugetlb entries within a
* given vma.
*/
- err = walk_hugetlb_range(vma, addr, next, walk);
+ err = walk_hugetlb_range(addr, next, walk);
if (err)
break;
pgd = pgd_offset(walk->mm, next);
_
--
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