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Date: Wed, 30 Jan 2013 16:26:19 -0800
From: Michel Lespinasse <walken@...gle.com>
To: Andrea Arcangeli <aarcange@...hat.com>,
Rik van Riel <riel@...hat.com>, Mel Gorman <mgorman@...e.de>,
Hugh Dickins <hughd@...gle.com>,
Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] mm: accelerate mm_populate() treatment of THP pages
This change adds a page_mask argument to follow_page.
follow_page sets *page_mask to HPAGE_PMD_NR - 1 when it encounters a THP page,
and to 0 in other cases.
__get_user_pages() makes use of this in order to accelerate populating
THP ranges - that is, when both the pages and vmas arrays are NULL,
we don't need to iterate HPAGE_PMD_NR times to cover a single THP page
(and we also avoid taking mm->page_table_lock that many times).
Other follow_page() call sites can safely ignore the value returned in
*page_mask.
Signed-off-by: Michel Lespinasse <walken@...gle.com>
---
arch/ia64/xen/xencomm.c | 3 ++-
arch/powerpc/kernel/vdso.c | 9 +++++----
arch/s390/mm/pgtable.c | 3 ++-
include/linux/mm.h | 2 +-
mm/ksm.c | 10 +++++++---
mm/memory.c | 25 +++++++++++++++++++------
mm/migrate.c | 7 +++++--
mm/mlock.c | 4 +++-
8 files changed, 44 insertions(+), 19 deletions(-)
diff --git a/arch/ia64/xen/xencomm.c b/arch/ia64/xen/xencomm.c
index 73d903ca2d64..c5dcf3a574e9 100644
--- a/arch/ia64/xen/xencomm.c
+++ b/arch/ia64/xen/xencomm.c
@@ -44,6 +44,7 @@ xencomm_vtop(unsigned long vaddr)
{
struct page *page;
struct vm_area_struct *vma;
+ long page_mask;
if (vaddr == 0)
return 0UL;
@@ -98,7 +99,7 @@ xencomm_vtop(unsigned long vaddr)
return ~0UL;
/* We assume the page is modified. */
- page = follow_page(vma, vaddr, FOLL_WRITE | FOLL_TOUCH);
+ page = follow_page(vma, vaddr, FOLL_WRITE | FOLL_TOUCH, &page_mask);
if (IS_ERR_OR_NULL(page))
return ~0UL;
diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index 1b2076f049ce..a529502d60f9 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -156,6 +156,7 @@ static void dump_one_vdso_page(struct page *pg, struct page *upg)
static void dump_vdso_pages(struct vm_area_struct * vma)
{
int i;
+ long page_mask;
if (!vma || is_32bit_task()) {
printk("vDSO32 @ %016lx:\n", (unsigned long)vdso32_kbase);
@@ -163,8 +164,8 @@ static void dump_vdso_pages(struct vm_area_struct * vma)
struct page *pg = virt_to_page(vdso32_kbase +
i*PAGE_SIZE);
struct page *upg = (vma && vma->vm_mm) ?
- follow_page(vma, vma->vm_start + i*PAGE_SIZE, 0)
- : NULL;
+ follow_page(vma, vma->vm_start + i*PAGE_SIZE,
+ 0, &page_mask) : NULL;
dump_one_vdso_page(pg, upg);
}
}
@@ -174,8 +175,8 @@ static void dump_vdso_pages(struct vm_area_struct * vma)
struct page *pg = virt_to_page(vdso64_kbase +
i*PAGE_SIZE);
struct page *upg = (vma && vma->vm_mm) ?
- follow_page(vma, vma->vm_start + i*PAGE_SIZE, 0)
- : NULL;
+ follow_page(vma, vma->vm_start + i*PAGE_SIZE,
+ 0, &page_mask) : NULL;
dump_one_vdso_page(pg, upg);
}
}
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index ae44d2a34313..63e897a6cf45 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -792,9 +792,10 @@ void thp_split_vma(struct vm_area_struct *vma)
{
unsigned long addr;
struct page *page;
+ long page_mask;
for (addr = vma->vm_start; addr < vma->vm_end; addr += PAGE_SIZE) {
- page = follow_page(vma, addr, FOLL_SPLIT);
+ page = follow_page(vma, addr, FOLL_SPLIT, &page_mask);
}
}
diff --git a/include/linux/mm.h b/include/linux/mm.h
index d5716094f191..6dc0ce370df5 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1636,7 +1636,7 @@ int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
unsigned long pfn);
struct page *follow_page(struct vm_area_struct *, unsigned long address,
- unsigned int foll_flags);
+ unsigned int foll_flags, long *page_mask);
#define FOLL_WRITE 0x01 /* check pte is writable */
#define FOLL_TOUCH 0x02 /* mark page accessed */
#define FOLL_GET 0x04 /* do get_page on page */
diff --git a/mm/ksm.c b/mm/ksm.c
index 51573858938d..76dfb7133aa4 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -330,10 +330,11 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr)
{
struct page *page;
int ret = 0;
+ long page_mask;
do {
cond_resched();
- page = follow_page(vma, addr, FOLL_GET);
+ page = follow_page(vma, addr, FOLL_GET, &page_mask);
if (IS_ERR_OR_NULL(page))
break;
if (PageKsm(page))
@@ -427,13 +428,14 @@ static struct page *get_mergeable_page(struct rmap_item *rmap_item)
unsigned long addr = rmap_item->address;
struct vm_area_struct *vma;
struct page *page;
+ long page_mask;
down_read(&mm->mmap_sem);
vma = find_mergeable_vma(mm, addr);
if (!vma)
goto out;
- page = follow_page(vma, addr, FOLL_GET);
+ page = follow_page(vma, addr, FOLL_GET, &page_mask);
if (IS_ERR_OR_NULL(page))
goto out;
if (PageAnon(page) || page_trans_compound_anon(page)) {
@@ -1289,6 +1291,7 @@ static struct rmap_item *scan_get_next_rmap_item(struct page **page)
struct mm_slot *slot;
struct vm_area_struct *vma;
struct rmap_item *rmap_item;
+ long page_mask;
if (list_empty(&ksm_mm_head.mm_list))
return NULL;
@@ -1342,7 +1345,8 @@ next_mm:
while (ksm_scan.address < vma->vm_end) {
if (ksm_test_exit(mm))
break;
- *page = follow_page(vma, ksm_scan.address, FOLL_GET);
+ *page = follow_page(vma, ksm_scan.address, FOLL_GET,
+ &page_mask);
if (IS_ERR_OR_NULL(*page)) {
ksm_scan.address += PAGE_SIZE;
cond_resched();
diff --git a/mm/memory.c b/mm/memory.c
index 381b78c20d84..1becba27c28a 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1470,7 +1470,7 @@ EXPORT_SYMBOL_GPL(zap_vma_ptes);
* by a page descriptor (see also vm_normal_page()).
*/
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
- unsigned int flags)
+ unsigned int flags, long *page_mask)
{
pgd_t *pgd;
pud_t *pud;
@@ -1480,6 +1480,8 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
struct page *page;
struct mm_struct *mm = vma->vm_mm;
+ *page_mask = 0;
+
page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
if (!IS_ERR(page)) {
BUG_ON(flags & FOLL_GET);
@@ -1526,6 +1528,7 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
page = follow_trans_huge_pmd(vma, address,
pmd, flags);
spin_unlock(&mm->page_table_lock);
+ *page_mask = HPAGE_PMD_NR - 1;
goto out;
}
} else
@@ -1680,6 +1683,7 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
{
long i;
unsigned long vm_flags;
+ long page_mask;
if (nr_pages <= 0)
return 0;
@@ -1757,6 +1761,7 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
get_page(page);
}
pte_unmap(pte);
+ page_mask = 0;
goto next_page;
}
@@ -1774,6 +1779,7 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
do {
struct page *page;
unsigned int foll_flags = gup_flags;
+ long page_increm;
/*
* If we have a pending SIGKILL, don't keep faulting
@@ -1783,7 +1789,8 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
return i ? i : -ERESTARTSYS;
cond_resched();
- while (!(page = follow_page(vma, start, foll_flags))) {
+ while (!(page = follow_page(vma, start, foll_flags,
+ &page_mask))) {
int ret;
unsigned int fault_flags = 0;
@@ -1857,13 +1864,19 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
flush_anon_page(vma, page, start);
flush_dcache_page(page);
+ page_mask = 0;
}
next_page:
- if (vmas)
+ if (vmas) {
vmas[i] = vma;
- i++;
- start += PAGE_SIZE;
- nr_pages--;
+ page_mask = 0;
+ }
+ page_increm = 1 + (~(start >> PAGE_SHIFT) & page_mask);
+ if (page_increm > nr_pages)
+ page_increm = nr_pages;
+ i += page_increm;
+ start += page_increm * PAGE_SIZE;
+ nr_pages -= page_increm;
} while (nr_pages && start < vma->vm_end);
} while (nr_pages);
return i;
diff --git a/mm/migrate.c b/mm/migrate.c
index c38778610aa8..daa5726c9c46 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1124,6 +1124,7 @@ static int do_move_page_to_node_array(struct mm_struct *mm,
int err;
struct page_to_node *pp;
LIST_HEAD(pagelist);
+ long page_mask;
down_read(&mm->mmap_sem);
@@ -1139,7 +1140,8 @@ static int do_move_page_to_node_array(struct mm_struct *mm,
if (!vma || pp->addr < vma->vm_start || !vma_migratable(vma))
goto set_status;
- page = follow_page(vma, pp->addr, FOLL_GET|FOLL_SPLIT);
+ page = follow_page(vma, pp->addr, FOLL_GET | FOLL_SPLIT,
+ &page_mask);
err = PTR_ERR(page);
if (IS_ERR(page))
@@ -1291,6 +1293,7 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
const void __user **pages, int *status)
{
unsigned long i;
+ long page_mask;
down_read(&mm->mmap_sem);
@@ -1304,7 +1307,7 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
if (!vma || addr < vma->vm_start)
goto set_status;
- page = follow_page(vma, addr, 0);
+ page = follow_page(vma, addr, 0, &page_mask);
err = PTR_ERR(page);
if (IS_ERR(page))
diff --git a/mm/mlock.c b/mm/mlock.c
index e1fa9e4b0a66..2694f17cca2d 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -223,6 +223,7 @@ void munlock_vma_pages_range(struct vm_area_struct *vma,
unsigned long start, unsigned long end)
{
unsigned long addr;
+ long page_mask;
lru_add_drain();
vma->vm_flags &= ~VM_LOCKED;
@@ -236,7 +237,8 @@ void munlock_vma_pages_range(struct vm_area_struct *vma,
* suits munlock very well (and if somehow an abnormal page
* has sneaked into the range, we won't oops here: great).
*/
- page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
+ page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP,
+ &page_mask);
if (page && !IS_ERR(page)) {
lock_page(page);
munlock_vma_page(page);
--
1.8.1
--
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