[PATCH 23/49] mm: mempolicy: Implement change_prot_numa() in terms of change_protection()

From: Mel Gorman
Date: Fri Dec 07 2012 - 05:24:29 EST

This patch converts change_prot_numa() to use change_protection(). As
pte_numa and friends check the PTE bits directly it is necessary for
change_protection() to use pmd_mknuma(). Hence the required
modifications to change_protection() are a little clumsy but the
end result is that most of the numa page table helpers are just one or
two instructions.

Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
---
include/linux/huge_mm.h | 3 +-
include/linux/mm.h | 4 +-
mm/huge_memory.c | 14 ++++-
mm/mempolicy.c | 137 +++++------------------------------------------
mm/mprotect.c | 72 +++++++++++++++++++------
5 files changed, 85 insertions(+), 145 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index dabb510..027ad04 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -27,7 +27,8 @@ extern int move_huge_pmd(struct vm_area_struct *vma,
unsigned long new_addr, unsigned long old_end,
pmd_t *old_pmd, pmd_t *new_pmd);
extern int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
- unsigned long addr, pgprot_t newprot);
+ unsigned long addr, pgprot_t newprot,
+ int prot_numa);

enum transparent_hugepage_flag {
TRANSPARENT_HUGEPAGE_FLAG,
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 471185e..d04c2f0 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1080,7 +1080,7 @@ extern unsigned long do_mremap(unsigned long addr,
unsigned long flags, unsigned long new_addr);
extern unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
unsigned long end, pgprot_t newprot,
- int dirty_accountable);
+ int dirty_accountable, int prot_numa);
extern int mprotect_fixup(struct vm_area_struct *vma,
struct vm_area_struct **pprev, unsigned long start,
unsigned long end, unsigned long newflags);
@@ -1552,7 +1552,7 @@ static inline pgprot_t vm_get_page_prot(unsigned long vm_flags)
#endif

#ifdef CONFIG_ARCH_USES_NUMA_PROT_NONE
-void change_prot_numa(struct vm_area_struct *vma,
+unsigned long change_prot_numa(struct vm_area_struct *vma,
unsigned long start, unsigned long end);
#endif

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index df1af09..68e0412 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1146,7 +1146,7 @@ out:
}

int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
- unsigned long addr, pgprot_t newprot)
+ unsigned long addr, pgprot_t newprot, int prot_numa)
{
struct mm_struct *mm = vma->vm_mm;
int ret = 0;
@@ -1154,7 +1154,17 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
if (__pmd_trans_huge_lock(pmd, vma) == 1) {
pmd_t entry;
entry = pmdp_get_and_clear(mm, addr, pmd);
- entry = pmd_modify(entry, newprot);
+ if (!prot_numa)
+ entry = pmd_modify(entry, newprot);
+ else {
+ struct page *page = pmd_page(*pmd);
+
+ /* only check non-shared pages */
+ if (page_mapcount(page) == 1 &&
+ !pmd_numa(*pmd)) {
+ entry = pmd_mknuma(entry);
+ }
+ }
set_pmd_at(mm, addr, pmd, entry);
spin_unlock(&vma->vm_mm->page_table_lock);
ret = 1;
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 51d3ebd..75d4600 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -568,134 +568,23 @@ static inline int check_pgd_range(struct vm_area_struct *vma,

#ifdef CONFIG_ARCH_USES_NUMA_PROT_NONE
/*
- * Here we search for not shared page mappings (mapcount == 1) and we
- * set up the pmd/pte_numa on those mappings so the very next access
- * will fire a NUMA hinting page fault.
+ * This is used to mark a range of virtual addresses to be inaccessible.
+ * These are later cleared by a NUMA hinting fault. Depending on these
+ * faults, pages may be migrated for better NUMA placement.
+ *
+ * This is assuming that NUMA faults are handled using PROT_NONE. If
+ * an architecture makes a different choice, it will need further
+ * changes to the core.
*/
-static int
-change_prot_numa_range(struct mm_struct *mm, struct vm_area_struct *vma,
- unsigned long address)
-{
- pgd_t *pgd;
- pud_t *pud;
- pmd_t *pmd;
- pte_t *pte, *_pte;
- struct page *page;
- unsigned long _address, end;
- spinlock_t *ptl;
- int ret = 0;
-
- VM_BUG_ON(address & ~PAGE_MASK);
-
- pgd = pgd_offset(mm, address);
- if (!pgd_present(*pgd))
- goto out;
-
- pud = pud_offset(pgd, address);
- if (!pud_present(*pud))
- goto out;
-
- pmd = pmd_offset(pud, address);
- if (pmd_none(*pmd))
- goto out;
-
- if (pmd_trans_huge_lock(pmd, vma) == 1) {
- int page_nid;
- ret = HPAGE_PMD_NR;
-
- VM_BUG_ON(address & ~HPAGE_PMD_MASK);
-
- if (pmd_numa(*pmd)) {
- spin_unlock(&mm->page_table_lock);
- goto out;
- }
-
- page = pmd_page(*pmd);
-
- /* only check non-shared pages */
- if (page_mapcount(page) != 1) {
- spin_unlock(&mm->page_table_lock);
- goto out;
- }
-
- page_nid = page_to_nid(page);
-
- if (pmd_numa(*pmd)) {
- spin_unlock(&mm->page_table_lock);
- goto out;
- }
-
- set_pmd_at(mm, address, pmd, pmd_mknuma(*pmd));
- ret += HPAGE_PMD_NR;
- /* defer TLB flush to lower the overhead */
- spin_unlock(&mm->page_table_lock);
- goto out;
- }
-
- if (pmd_trans_unstable(pmd))
- goto out;
- VM_BUG_ON(!pmd_present(*pmd));
-
- end = min(vma->vm_end, (address + PMD_SIZE) & PMD_MASK);
- pte = pte_offset_map_lock(mm, pmd, address, &ptl);
- for (_address = address, _pte = pte; _address < end;
- _pte++, _address += PAGE_SIZE) {
- pte_t pteval = *_pte;
- if (!pte_present(pteval))
- continue;
- if (pte_numa(pteval))
- continue;
- page = vm_normal_page(vma, _address, pteval);
- if (unlikely(!page))
- continue;
- /* only check non-shared pages */
- if (page_mapcount(page) != 1)
- continue;
-
- set_pte_at(mm, _address, _pte, pte_mknuma(pteval));
-
- /* defer TLB flush to lower the overhead */
- ret++;
- }
- pte_unmap_unlock(pte, ptl);
-
- if (ret && !pmd_numa(*pmd)) {
- spin_lock(&mm->page_table_lock);
- set_pmd_at(mm, address, pmd, pmd_mknuma(*pmd));
- spin_unlock(&mm->page_table_lock);
- /* defer TLB flush to lower the overhead */
- }
-
-out:
- return ret;
-}
-
-/* Assumes mmap_sem is held */
-void
-change_prot_numa(struct vm_area_struct *vma,
- unsigned long address, unsigned long end)
+unsigned long change_prot_numa(struct vm_area_struct *vma,
+ unsigned long addr, unsigned long end)
{
- struct mm_struct *mm = vma->vm_mm;
- int progress = 0;
-
- while (address < end) {
- VM_BUG_ON(address < vma->vm_start ||
- address + PAGE_SIZE > vma->vm_end);
+ int nr_updated;
+ BUILD_BUG_ON(_PAGE_NUMA != _PAGE_PROTNONE);

- progress += change_prot_numa_range(mm, vma, address);
- address = (address + PMD_SIZE) & PMD_MASK;
- }
+ nr_updated = change_protection(vma, addr, end, vma->vm_page_prot, 0, 1);

- /*
- * Flush the TLB for the mm to start the NUMA hinting
- * page faults after we finish scanning this vma part
- * if there were any PTE updates
- */
- if (progress) {
- mmu_notifier_invalidate_range_start(vma->vm_mm, address, end);
- flush_tlb_range(vma, address, end);
- mmu_notifier_invalidate_range_end(vma->vm_mm, address, end);
- }
+ return nr_updated;
}
#else
static unsigned long change_prot_numa(struct vm_area_struct *vma,
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 7c3628a..8abf7c6 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -35,10 +35,11 @@ static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
}
#endif

-static unsigned long change_pte_range(struct mm_struct *mm, pmd_t *pmd,
+static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
unsigned long addr, unsigned long end, pgprot_t newprot,
- int dirty_accountable)
+ int dirty_accountable, int prot_numa)
{
+ struct mm_struct *mm = vma->vm_mm;
pte_t *pte, oldpte;
spinlock_t *ptl;
unsigned long pages = 0;
@@ -49,19 +50,39 @@ static unsigned long change_pte_range(struct mm_struct *mm, pmd_t *pmd,
oldpte = *pte;
if (pte_present(oldpte)) {
pte_t ptent;
+ bool updated = false;

ptent = ptep_modify_prot_start(mm, addr, pte);
- ptent = pte_modify(ptent, newprot);
+ if (!prot_numa) {
+ ptent = pte_modify(ptent, newprot);
+ updated = true;
+ } else {
+ struct page *page;
+
+ page = vm_normal_page(vma, addr, oldpte);
+ if (page) {
+ /* only check non-shared pages */
+ if (!pte_numa(oldpte) &&
+ page_mapcount(page) == 1) {
+ ptent = pte_mknuma(ptent);
+ updated = true;
+ }
+ }
+ }

/*
* Avoid taking write faults for pages we know to be
* dirty.
*/
- if (dirty_accountable && pte_dirty(ptent))
+ if (dirty_accountable && pte_dirty(ptent)) {
ptent = pte_mkwrite(ptent);
+ updated = true;
+ }
+
+ if (updated)
+ pages++;

ptep_modify_prot_commit(mm, addr, pte, ptent);
- pages++;
} else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) {
swp_entry_t entry = pte_to_swp_entry(oldpte);

@@ -83,9 +104,25 @@ static unsigned long change_pte_range(struct mm_struct *mm, pmd_t *pmd,
return pages;
}

+#ifdef CONFIG_BALANCE_NUMA
+static inline void change_pmd_protnuma(struct mm_struct *mm, unsigned long addr,
+ pmd_t *pmd)
+{
+ spin_lock(&mm->page_table_lock);
+ set_pmd_at(mm, addr & PMD_MASK, pmd, pmd_mknuma(*pmd));
+ spin_unlock(&mm->page_table_lock);
+}
+#else
+static inline void change_pmd_protnuma(struct mm_struct *mm, unsigned long addr,
+ pmd_t *pmd)
+{
+ BUG();
+}
+#endif /* CONFIG_BALANCE_NUMA */
+
static inline unsigned long change_pmd_range(struct vm_area_struct *vma, pud_t *pud,
unsigned long addr, unsigned long end, pgprot_t newprot,
- int dirty_accountable)
+ int dirty_accountable, int prot_numa)
{
pmd_t *pmd;
unsigned long next;
@@ -97,7 +134,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma, pud_t *
if (pmd_trans_huge(*pmd)) {
if (next - addr != HPAGE_PMD_SIZE)
split_huge_page_pmd(vma->vm_mm, pmd);
- else if (change_huge_pmd(vma, pmd, addr, newprot)) {
+ else if (change_huge_pmd(vma, pmd, addr, newprot, prot_numa)) {
pages += HPAGE_PMD_NR;
continue;
}
@@ -105,8 +142,11 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma, pud_t *
}
if (pmd_none_or_clear_bad(pmd))
continue;
- pages += change_pte_range(vma->vm_mm, pmd, addr, next, newprot,
- dirty_accountable);
+ pages += change_pte_range(vma, pmd, addr, next, newprot,
+ dirty_accountable, prot_numa);
+
+ if (prot_numa)
+ change_pmd_protnuma(vma->vm_mm, addr, pmd);
} while (pmd++, addr = next, addr != end);

return pages;
@@ -114,7 +154,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma, pud_t *

static inline unsigned long change_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
unsigned long addr, unsigned long end, pgprot_t newprot,
- int dirty_accountable)
+ int dirty_accountable, int prot_numa)
{
pud_t *pud;
unsigned long next;
@@ -126,7 +166,7 @@ static inline unsigned long change_pud_range(struct vm_area_struct *vma, pgd_t *
if (pud_none_or_clear_bad(pud))
continue;
pages += change_pmd_range(vma, pud, addr, next, newprot,
- dirty_accountable);
+ dirty_accountable, prot_numa);
} while (pud++, addr = next, addr != end);

return pages;
@@ -134,7 +174,7 @@ static inline unsigned long change_pud_range(struct vm_area_struct *vma, pgd_t *

static unsigned long change_protection_range(struct vm_area_struct *vma,
unsigned long addr, unsigned long end, pgprot_t newprot,
- int dirty_accountable)
+ int dirty_accountable, int prot_numa)
{
struct mm_struct *mm = vma->vm_mm;
pgd_t *pgd;
@@ -150,7 +190,7 @@ static unsigned long change_protection_range(struct vm_area_struct *vma,
if (pgd_none_or_clear_bad(pgd))
continue;
pages += change_pud_range(vma, pgd, addr, next, newprot,
- dirty_accountable);
+ dirty_accountable, prot_numa);
} while (pgd++, addr = next, addr != end);

/* Only flush the TLB if we actually modified any entries: */
@@ -162,7 +202,7 @@ static unsigned long change_protection_range(struct vm_area_struct *vma,

unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
unsigned long end, pgprot_t newprot,
- int dirty_accountable)
+ int dirty_accountable, int prot_numa)
{
struct mm_struct *mm = vma->vm_mm;
unsigned long pages;
@@ -171,7 +211,7 @@ unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
if (is_vm_hugetlb_page(vma))
pages = hugetlb_change_protection(vma, start, end, newprot);
else
- pages = change_protection_range(vma, start, end, newprot, dirty_accountable);
+ pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
mmu_notifier_invalidate_range_end(mm, start, end);

return pages;
@@ -249,7 +289,7 @@ success:
dirty_accountable = 1;
}

- change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable);
+ change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable, 0);

vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
vm_stat_account(mm, newflags, vma->vm_file, nrpages);
--
1.7.9.2

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