[RFC/PATCH] Shared Page Tables [2/2]
From: Dave McCracken
Date: Mon Apr 10 2006 - 12:13:50 EST
Share page tables when possible.
Signed-off-by: Dave McCracken <dmccr@xxxxxxxxxx>
----
arch/i386/Kconfig | 12 +
arch/s390/Kconfig | 22 +
arch/x86_64/Kconfig | 22 +
include/asm-generic/pgtable.h | 31 ++
include/linux/mm.h | 12 -
include/linux/ptshare.h | 175 +++++++++++++++
include/linux/rmap.h | 2
include/linux/sched.h | 2
mm/Makefile | 1
mm/filemap_xip.c | 3
mm/fremap.c | 6
mm/hugetlb.c | 54 +++-
mm/memory.c | 39 ++-
mm/mmap.c | 3
mm/mprotect.c | 10
mm/mremap.c | 7
mm/ptshare.c | 463 ++++++++++++++++++++++++++++++++++++++++++
mm/rmap.c | 21 +
18 files changed, 846 insertions(+), 39 deletions(-)
----
--- 2.6.17-rc1-macro/./arch/i386/Kconfig 2006-04-02 22:22:10.000000000 -0500
+++ 2.6.17-rc1-shpt/./arch/i386/Kconfig 2006-04-10 08:46:01.000000000 -0500
@@ -512,6 +512,18 @@ config X86_PAE
depends on HIGHMEM64G
default y
+config PTSHARE
+ bool "Share page tables"
+ default y
+ help
+ Turn on sharing of page tables between processes for large shared
+ memory regions.
+
+config PTSHARE_PTE
+ bool
+ depends on PTSHARE
+ default y
+
# Common NUMA Features
config NUMA
bool "Numa Memory Allocation and Scheduler Support"
--- 2.6.17-rc1-macro/./arch/s390/Kconfig 2006-04-02 22:22:10.000000000 -0500
+++ 2.6.17-rc1-shpt/./arch/s390/Kconfig 2006-04-10 08:46:01.000000000 -0500
@@ -218,6 +218,28 @@ config WARN_STACK_SIZE
source "mm/Kconfig"
+config PTSHARE
+ bool "Share page tables"
+ default y
+ help
+ Turn on sharing of page tables between processes for large shared
+ memory regions.
+
+menu "Page table levels to share"
+ depends on PTSHARE
+
+config PTSHARE_PTE
+ bool "Bottom level table (PTE)"
+ depends on PTSHARE
+ default y
+
+config PTSHARE_PMD
+ bool "Middle level table (PMD)"
+ depends on PTSHARE && 64BIT
+ default y
+
+endmenu
+
comment "I/O subsystem configuration"
config MACHCHK_WARNING
--- 2.6.17-rc1-macro/./arch/x86_64/Kconfig 2006-04-02 22:22:10.000000000 -0500
+++ 2.6.17-rc1-shpt/./arch/x86_64/Kconfig 2006-04-10 08:46:01.000000000 -0500
@@ -302,6 +302,28 @@ config NUMA_EMU
into virtual nodes when booted with "numa=fake=N", where N is the
number of nodes. This is only useful for debugging.
+config PTSHARE
+ bool "Share page tables"
+ default y
+ help
+ Turn on sharing of page tables between processes for large shared
+ memory regions.
+
+config PTSHARE_PTE
+ bool
+ depends on PTSHARE
+ default y
+
+config PTSHARE_PMD
+ bool
+ depends on PTSHARE
+ default y
+
+config PTSHARE_HUGEPAGE
+ bool
+ depends on PTSHARE && PTSHARE_PMD
+ default y
+
config ARCH_DISCONTIGMEM_ENABLE
bool
depends on NUMA
--- 2.6.17-rc1-macro/./include/asm-generic/pgtable.h 2006-04-02 22:22:10.000000000 -0500
+++ 2.6.17-rc1-shpt/./include/asm-generic/pgtable.h 2006-04-10 08:46:01.000000000 -0500
@@ -127,6 +127,16 @@ do { \
})
#endif
+#ifndef __HAVE_ARCH_PTEP_CLEAR_FLUSH_ALL
+#define ptep_clear_flush_all(__vma, __address, __ptep) \
+({ \
+ pte_t __pte; \
+ __pte = ptep_get_and_clear((__vma)->vm_mm, __address, __ptep); \
+ flush_tlb_all(); \
+ __pte; \
+})
+#endif
+
#ifndef __HAVE_ARCH_PTEP_SET_WRPROTECT
struct mm_struct;
static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long address, pte_t *ptep)
@@ -173,6 +183,27 @@ static inline void ptep_set_wrprotect(st
#endif
/*
+ * Some architectures might need flushes when higher levels of page table
+ * are unshared.
+ */
+
+#ifndef __HAVE_ARCH_PMD_CLEAR_FLUSH
+#define pmd_clear_flush(__mm, __addr, __pmd) \
+({ \
+ pmd_clear(__pmd); \
+ flush_tlb_all(); \
+})
+#endif
+
+#ifndef __HAVE_ARCH_PUD_CLEAR_FLUSH
+#define pud_clear_flush(__mm, __addr, __pud) \
+({ \
+ pud_clear(__pud); \
+ flush_tlb_all(); \
+})
+#endif
+
+/*
* When walking page tables, get the address of the next boundary,
* or the end address of the range if that comes earlier. Although no
* vma end wraps to 0, rounded up __boundary may wrap to 0 throughout.
--- 2.6.17-rc1-macro/./include/linux/mm.h 2006-04-02 22:22:10.000000000 -0500
+++ 2.6.17-rc1-shpt/./include/linux/mm.h 2006-04-10 08:46:01.000000000 -0500
@@ -166,6 +166,8 @@ extern unsigned int kobjsize(const void
#define VM_NONLINEAR 0x00800000 /* Is non-linear (remap_file_pages) */
#define VM_MAPPED_COPY 0x01000000 /* T if mapped copy of data (nommu mmap) */
#define VM_INSERTPAGE 0x02000000 /* The vma has had "vm_insert_page()" done on it */
+#define VM_TRANSITION 0x04000000 /* The vma is in transition (mprotect, mremap, etc) */
+#define VM_PTSHARE 0x08000000 /* This vma has shared one or more page tables */
#ifndef VM_STACK_DEFAULT_FLAGS /* arch can override this */
#define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
@@ -242,7 +244,7 @@ struct page {
* see PAGE_MAPPING_ANON below.
*/
};
-#if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS
+#if (NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS) || defined(CONFIG_PTSHARE)
spinlock_t ptl;
#endif
};
@@ -815,19 +817,19 @@ static inline pmd_t *pmd_alloc(struct mm
}
#endif /* CONFIG_MMU && !__ARCH_HAS_4LEVEL_HACK */
-#if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS
+#if (NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS) || defined(CONFIG_PTSHARE)
/*
* We tuck a spinlock to guard each pagetable page into its struct page,
* at page->private, with BUILD_BUG_ON to make sure that this will not
* overflow into the next struct page (as it might with DEBUG_SPINLOCK).
* When freeing, reset page->mapping so free_pages_check won't complain.
*/
-#define __pte_lockptr(page) &((page)->ptl)
+#define __pt_lockptr(page) &((page)->ptl)
#define pte_lock_init(_page) do { \
- spin_lock_init(__pte_lockptr(_page)); \
+ spin_lock_init(__pt_lockptr(_page)); \
} while (0)
#define pte_lock_deinit(page) ((page)->mapping = NULL)
-#define pte_lockptr(mm, pmd) ({(void)(mm); __pte_lockptr(pmd_page(*(pmd)));})
+#define pte_lockptr(mm, pmd) ({(void)(mm); __pt_lockptr(pmd_page(*(pmd)));})
#else
/*
* We use mm->page_table_lock to guard all pagetable pages of the mm.
--- 2.6.17-rc1-macro/./include/linux/rmap.h 2006-04-02 22:22:10.000000000 -0500
+++ 2.6.17-rc1-shpt/./include/linux/rmap.h 2006-04-10 08:46:01.000000000 -0500
@@ -98,7 +98,7 @@ void remove_from_swap(struct page *page)
* Called from mm/filemap_xip.c to unmap empty zero page
*/
pte_t *page_check_address(struct page *, struct mm_struct *,
- unsigned long, spinlock_t **);
+ unsigned long, spinlock_t **, int *);
/*
* Used by swapoff to help locate where page is expected in vma.
--- 2.6.17-rc1-macro/./include/linux/sched.h 2006-04-02 22:22:10.000000000 -0500
+++ 2.6.17-rc1-shpt/./include/linux/sched.h 2006-04-10 08:46:01.000000000 -0500
@@ -254,7 +254,7 @@ arch_get_unmapped_area_topdown(struct fi
extern void arch_unmap_area(struct mm_struct *, unsigned long);
extern void arch_unmap_area_topdown(struct mm_struct *, unsigned long);
-#if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS
+#if (NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS) || defined(CONFIG_PTSHARE)
/*
* The mm counters are not protected by its page_table_lock,
* so must be incremented atomically.
--- 2.6.17-rc1-macro/./include/linux/ptshare.h 1969-12-31 18:00:00.000000000 -0600
+++ 2.6.17-rc1-shpt/./include/linux/ptshare.h 2006-04-10 08:46:01.000000000 -0500
@@ -0,0 +1,175 @@
+#ifndef _LINUX_PTSHARE_H
+#define _LINUX_PTSHARE_H
+
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2005
+ *
+ * Author: Dave McCracken <dmccr@xxxxxxxxxx>
+ */
+
+#undef PT_DEBUG
+
+#ifdef CONFIG_PTSHARE
+static inline int pt_is_shared(struct page *page)
+{
+ return (page_mapcount(page) > 0);
+}
+
+static inline void pt_increment_share(struct page *page)
+{
+ atomic_inc(&page->_mapcount);
+}
+
+static inline void pt_decrement_share(struct page *page)
+{
+ atomic_dec(&page->_mapcount);
+}
+
+static inline int pt_vmashared(struct vm_area_struct *vma) {
+ return vma->vm_flags & VM_PTSHARE;
+}
+extern void pt_unshare_range(struct vm_area_struct *vma, unsigned long address,
+ unsigned long end);
+#else /* CONFIG_PTSHARE */
+#define pt_is_shared(page) (0)
+#define pt_increment_share(page)
+#define pt_decrement_share(page)
+#define pt_vmashared(vma) 0
+#define pt_unshare_range(vma, address, end)
+#endif /* CONFIG_PTSHARE */
+
+#ifdef CONFIG_PTSHARE_PTE
+static inline int pt_is_shared_pte(pmd_t pmdval)
+{
+ struct page *page;
+
+ page = pmd_page(pmdval);
+ return pt_is_shared(page);
+}
+
+static inline void pt_increment_pte(pmd_t pmdval)
+{
+ struct page *page;
+
+ page = pmd_page(pmdval);
+ pt_increment_share(page);
+}
+
+static inline void pt_decrement_pte(pmd_t pmdval)
+{
+ struct page *page;
+
+ page = pmd_page(pmdval);
+ pt_decrement_share(page);
+}
+
+extern pte_t * pt_share_pte(struct vm_area_struct *vma, unsigned long address,
+ pmd_t *pmd);
+extern int pt_check_unshare_pte(struct mm_struct *mm, unsigned long address,
+ pmd_t *pmd);
+#else /* CONFIG_PTSHARE_PTE */
+static inline int pt_is_shared_pte(pmd_t pmdval)
+{
+ return 0;
+}
+static inline int pt_check_unshare_pte(struct mm_struct *mm, unsigned long address,
+ pmd_t *pmd)
+{
+ return 0;
+}
+#define pt_increment_pte(pmdval)
+#define pt_decrement_pte(pmdval)
+#define pt_share_pte(vma, address, pmd) pte_alloc_map(vma->vm_mm, pmd, address)
+#endif /* CONFIG_PTSHARE_PTE */
+
+#ifdef CONFIG_PTSHARE_PMD
+static inline int pt_is_shared_pmd(pud_t pudval)
+{
+ struct page *page;
+
+ page = pud_page(pudval);
+ return pt_is_shared(page);
+}
+
+static inline void pt_increment_pmd(pud_t pudval)
+{
+ struct page *page;
+
+ page = pud_page(pudval);
+ pt_increment_share(page);
+}
+
+static inline void pt_decrement_pmd(pud_t pudval)
+{
+ struct page *page;
+
+ page = pud_page(pudval);
+ pt_decrement_share(page);
+}
+extern pmd_t * pt_share_pmd(struct vm_area_struct *vma, unsigned long address,
+ pud_t *pud);
+extern int pt_check_unshare_pmd(struct mm_struct *mm, unsigned long address,
+ pud_t *pud);
+#else /* CONFIG_PTSHARE_PMD */
+static inline int pt_is_shared_pmd(pud_t pudval)
+{
+ return 0;
+}
+static inline int pt_check_unshare_pmd(struct mm_struct *mm, unsigned long address,
+ pud_t *pud)
+{
+ return 0;
+}
+#define pt_increment_pmd(pudval)
+#define pt_decrement_pmd(pudval)
+#define pt_share_pmd(vma, address, pud) pmd_alloc(vma->vm_mm, pud, address)
+#endif /* CONFIG_PTSHARE_PMD */
+
+#ifdef CONFIG_PTSHARE_HUGEPAGE
+extern pte_t *pt_share_hugepage(struct mm_struct *mm, struct vm_area_struct *vma,
+ unsigned long address);
+extern void pt_unshare_huge_range(struct vm_area_struct *vma, unsigned long address,
+ unsigned long end);
+#else
+#define pt_share_hugepage(mm, vma, address) huge_pte_alloc(mm, address)
+#define pt_unshare_huge_range(vma, address, end)
+#endif /* CONFIG_PTSHARE_HUGEPAGE */
+
+/*
+ * Locking macros...
+ * All levels of page table at or above the level(s) we share use page_table_lock.
+ * Each level below the share level uses the pt_lockptr in struct page in the level
+ * above.
+ */
+
+#ifdef CONFIG_PTSHARE_PMD
+#define pmd_lock_init(pmd) do { \
+ spin_lock_init(__pt_lockptr(virt_to_page(pmd))); \
+} while (0)
+#define pmd_lock_deinit(pmd) ((virt_to_page(pmd))->mapping = NULL)
+#define pmd_lockptr(mm, pmd) ({(void)(mm); __pt_lockptr(virt_to_page(pmd));})
+#else
+#define pmd_lock_init(pmd) do {} while (0)
+#define pmd_lock_deinit(pmd) do {} while (0)
+#define pmd_lockptr(mm, pmd) ({(void)(pmd); &(mm)->page_table_lock;})
+#endif
+#ifdef CONFIG_PTSHARE_HUGEPAGE
+#define hugepte_lockptr(mm, pte) pmd_lockptr(mm, pte)
+#else
+#define hugepte_lockptr(mm, pte) ({(void)(pte); &(mm)->page_table_lock;})
+#endif
+#endif /* _LINUX_PTSHARE_H */
--- 2.6.17-rc1-macro/./mm/Makefile 2006-04-02 22:22:10.000000000 -0500
+++ 2.6.17-rc1-shpt/./mm/Makefile 2006-04-10 08:47:12.000000000 -0500
@@ -23,4 +23,5 @@ obj-$(CONFIG_SLAB) += slab.o
obj-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o
obj-$(CONFIG_FS_XIP) += filemap_xip.o
obj-$(CONFIG_MIGRATION) += migrate.o
+obj-$(CONFIG_PTSHARE) += ptshare.o
--- 2.6.17-rc1-macro/./mm/filemap_xip.c 2006-04-02 22:22:10.000000000 -0500
+++ 2.6.17-rc1-shpt/./mm/filemap_xip.c 2006-04-10 08:46:01.000000000 -0500
@@ -174,6 +174,7 @@ __xip_unmap (struct address_space * mapp
unsigned long address;
pte_t *pte;
pte_t pteval;
+ int shared;
spinlock_t *ptl;
struct page *page;
@@ -184,7 +185,7 @@ __xip_unmap (struct address_space * mapp
((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
BUG_ON(address < vma->vm_start || address >= vma->vm_end);
page = ZERO_PAGE(address);
- pte = page_check_address(page, mm, address, &ptl);
+ pte = page_check_address(page, mm, address, &ptl, &shared);
if (pte) {
/* Nuke the page table entry. */
flush_cache_page(vma, address, pte_pfn(*pte));
--- 2.6.17-rc1-macro/./mm/fremap.c 2006-04-02 22:22:10.000000000 -0500
+++ 2.6.17-rc1-shpt/./mm/fremap.c 2006-04-10 08:46:01.000000000 -0500
@@ -15,6 +15,7 @@
#include <linux/rmap.h>
#include <linux/module.h>
#include <linux/syscalls.h>
+#include <linux/ptshare.h>
#include <asm/mmu_context.h>
#include <asm/cacheflush.h>
@@ -193,6 +194,10 @@ asmlinkage long sys_remap_file_pages(uns
has_write_lock = 1;
goto retry;
}
+ vma->vm_flags |= VM_TRANSITION;
+ if (pt_vmashared(vma))
+ pt_unshare_range(vma, vma->vm_start, vma->vm_end);
+
mapping = vma->vm_file->f_mapping;
spin_lock(&mapping->i_mmap_lock);
flush_dcache_mmap_lock(mapping);
@@ -201,6 +206,7 @@ asmlinkage long sys_remap_file_pages(uns
vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
flush_dcache_mmap_unlock(mapping);
spin_unlock(&mapping->i_mmap_lock);
+ vma->vm_flags &= ~VM_TRANSITION;
}
err = vma->vm_ops->populate(vma, start, size,
--- 2.6.17-rc1-macro/./mm/hugetlb.c 2006-04-02 22:22:10.000000000 -0500
+++ 2.6.17-rc1-shpt/./mm/hugetlb.c 2006-04-10 09:05:39.000000000 -0500
@@ -11,6 +11,7 @@
#include <linux/highmem.h>
#include <linux/nodemask.h>
#include <linux/pagemap.h>
+#include <linux/ptshare.h>
#include <linux/mempolicy.h>
#include <linux/cpuset.h>
#include <linux/mutex.h>
@@ -437,6 +438,7 @@ int copy_hugetlb_page_range(struct mm_st
struct page *ptepage;
unsigned long addr;
int cow;
+ spinlock_t *src_ptl, *dst_ptl;
cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
@@ -447,8 +449,10 @@ int copy_hugetlb_page_range(struct mm_st
dst_pte = huge_pte_alloc(dst, addr);
if (!dst_pte)
goto nomem;
- spin_lock(&dst->page_table_lock);
- spin_lock(&src->page_table_lock);
+ dst_ptl = hugepte_lockptr(dst, dst_pte);
+ src_ptl = hugepte_lockptr(src, src_pte);
+ spin_lock(dst_ptl);
+ spin_lock(src_ptl);
if (!pte_none(*src_pte)) {
if (cow)
ptep_set_wrprotect(src, addr, src_pte);
@@ -458,8 +462,8 @@ int copy_hugetlb_page_range(struct mm_st
add_mm_counter(dst, file_rss, HPAGE_SIZE / PAGE_SIZE);
set_huge_pte_at(dst, addr, dst_pte, entry);
}
- spin_unlock(&src->page_table_lock);
- spin_unlock(&dst->page_table_lock);
+ spin_unlock(src_ptl);
+ spin_unlock(dst_ptl);
}
return 0;
@@ -475,12 +479,14 @@ void unmap_hugepage_range(struct vm_area
pte_t *ptep;
pte_t pte;
struct page *page;
+ spinlock_t *ptl = NULL, *new_ptl;
WARN_ON(!is_vm_hugetlb_page(vma));
BUG_ON(start & ~HPAGE_MASK);
BUG_ON(end & ~HPAGE_MASK);
- spin_lock(&mm->page_table_lock);
+ if (pt_vmashared(vma))
+ pt_unshare_huge_range(vma, start, end);
/* Update high watermark before we lower rss */
update_hiwater_rss(mm);
@@ -490,6 +496,13 @@ void unmap_hugepage_range(struct vm_area
if (!ptep)
continue;
+ new_ptl = hugepte_lockptr(mm, ptep);
+ if (new_ptl != ptl) {
+ if (ptl)
+ spin_unlock(ptl);
+ ptl = new_ptl;
+ spin_lock(ptl);
+ }
pte = huge_ptep_get_and_clear(mm, address, ptep);
if (pte_none(pte))
continue;
@@ -499,12 +512,15 @@ void unmap_hugepage_range(struct vm_area
add_mm_counter(mm, file_rss, (int) -(HPAGE_SIZE / PAGE_SIZE));
}
- spin_unlock(&mm->page_table_lock);
+ if (ptl)
+ spin_unlock(ptl);
+
flush_tlb_range(vma, start, end);
}
static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
- unsigned long address, pte_t *ptep, pte_t pte)
+ unsigned long address, pte_t *ptep, pte_t pte,
+ spinlock_t *ptl)
{
struct page *old_page, *new_page;
int avoidcopy;
@@ -527,9 +543,9 @@ static int hugetlb_cow(struct mm_struct
return VM_FAULT_OOM;
}
- spin_unlock(&mm->page_table_lock);
+ spin_unlock(ptl);
copy_huge_page(new_page, old_page, address);
- spin_lock(&mm->page_table_lock);
+ spin_lock(ptl);
ptep = huge_pte_offset(mm, address & HPAGE_MASK);
if (likely(pte_same(*ptep, pte))) {
@@ -553,6 +569,7 @@ int hugetlb_no_page(struct mm_struct *mm
struct page *page;
struct address_space *mapping;
pte_t new_pte;
+ spinlock_t *ptl;
mapping = vma->vm_file->f_mapping;
idx = ((address - vma->vm_start) >> HPAGE_SHIFT)
@@ -590,7 +607,8 @@ retry:
lock_page(page);
}
- spin_lock(&mm->page_table_lock);
+ ptl = hugepte_lockptr(mm, ptep);
+ spin_lock(ptl);
size = i_size_read(mapping->host) >> HPAGE_SHIFT;
if (idx >= size)
goto backout;
@@ -606,16 +624,16 @@ retry:
if (write_access && !(vma->vm_flags & VM_SHARED)) {
/* Optimization, do the COW without a second fault */
- ret = hugetlb_cow(mm, vma, address, ptep, new_pte);
+ ret = hugetlb_cow(mm, vma, address, ptep, new_pte, ptl);
}
- spin_unlock(&mm->page_table_lock);
+ spin_unlock(ptl);
unlock_page(page);
out:
return ret;
backout:
- spin_unlock(&mm->page_table_lock);
+ spin_unlock(ptl);
hugetlb_put_quota(mapping);
unlock_page(page);
put_page(page);
@@ -628,9 +646,10 @@ int hugetlb_fault(struct mm_struct *mm,
pte_t *ptep;
pte_t entry;
int ret;
+ spinlock_t *ptl;
static DEFINE_MUTEX(hugetlb_instantiation_mutex);
- ptep = huge_pte_alloc(mm, address);
+ ptep = pt_share_hugepage(mm, vma, address & HPAGE_MASK);
if (!ptep)
return VM_FAULT_OOM;
@@ -649,12 +668,13 @@ int hugetlb_fault(struct mm_struct *mm,
ret = VM_FAULT_MINOR;
- spin_lock(&mm->page_table_lock);
+ ptl = hugepte_lockptr(mm, ptep);
+ spin_lock(ptl);
/* Check for a racing update before calling hugetlb_cow */
if (likely(pte_same(entry, *ptep)))
if (write_access && !pte_write(entry))
- ret = hugetlb_cow(mm, vma, address, ptep, entry);
- spin_unlock(&mm->page_table_lock);
+ ret = hugetlb_cow(mm, vma, address, ptep, entry, ptl);
+ spin_unlock(ptl);
mutex_unlock(&hugetlb_instantiation_mutex);
return ret;
--- 2.6.17-rc1-macro/./mm/memory.c 2006-04-02 22:22:10.000000000 -0500
+++ 2.6.17-rc1-shpt/./mm/memory.c 2006-04-10 08:46:01.000000000 -0500
@@ -48,6 +48,7 @@
#include <linux/rmap.h>
#include <linux/module.h>
#include <linux/init.h>
+#include <linux/ptshare.h>
#include <asm/pgalloc.h>
#include <asm/uaccess.h>
@@ -144,6 +145,10 @@ static inline void free_pmd_range(struct
next = pmd_addr_end(addr, end);
if (pmd_none_or_clear_bad(pmd))
continue;
+ if (pt_is_shared_pte(*pmd)) {
+ if (pt_check_unshare_pte(tlb->mm, addr, pmd))
+ continue;
+ }
free_pte_range(tlb, pmd);
} while (pmd++, addr = next, addr != end);
@@ -160,6 +165,7 @@ static inline void free_pmd_range(struct
pmd = pmd_offset(pud, start);
pud_clear(pud);
+ pmd_lock_deinit(pmd);
pmd_free_tlb(tlb, pmd);
}
@@ -177,6 +183,10 @@ static inline void free_pud_range(struct
next = pud_addr_end(addr, end);
if (pud_none_or_clear_bad(pud))
continue;
+ if (pt_is_shared_pmd(*pud)) {
+ if (pt_check_unshare_pmd(tlb->mm, addr, pud))
+ continue;
+ }
free_pmd_range(tlb, pud, addr, next, floor, ceiling);
} while (pud++, addr = next, addr != end);
@@ -301,20 +311,21 @@ void free_pgtables(struct mmu_gather **t
int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
{
struct page *new = pte_alloc_one(mm, address);
+ spinlock_t *ptl = pmd_lockptr(mm, pmd);
+
if (!new)
return -ENOMEM;
pte_lock_init(new);
- spin_lock(&mm->page_table_lock);
+ spin_lock(ptl);
if (pmd_present(*pmd)) { /* Another has populated it */
pte_lock_deinit(new);
pte_free(new);
} else {
- mm->nr_ptes++;
inc_page_state(nr_page_table_pages);
pmd_populate(mm, pmd, new);
}
- spin_unlock(&mm->page_table_lock);
+ spin_unlock(ptl);
return 0;
}
@@ -581,7 +592,7 @@ int copy_page_range(struct mm_struct *ds
* readonly mappings. The tradeoff is that copy_page_range is more
* efficient than faulting.
*/
- if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
+ if (!(vma->vm_flags & (VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
if (!vma->anon_vma)
return 0;
}
@@ -613,6 +624,10 @@ static unsigned long zap_pte_range(struc
int file_rss = 0;
int anon_rss = 0;
+ if (pt_is_shared_pte(*pmd)) {
+ if (pt_check_unshare_pte(mm, addr, pmd))
+ return end;
+ }
pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
do {
pte_t ptent = *pte;
@@ -694,6 +709,10 @@ static inline unsigned long zap_pmd_rang
unsigned long next;
pmd = pmd_offset(pud, addr);
+ if (pt_is_shared_pmd(*pud)) {
+ if (pt_check_unshare_pmd(tlb->mm, addr, pud))
+ return end;
+ }
do {
next = pmd_addr_end(addr, end);
if (pmd_none_or_clear_bad(pmd)) {
@@ -2272,10 +2291,10 @@ int __handle_mm_fault(struct mm_struct *
pud = pud_alloc(mm, pgd, address);
if (!pud)
return VM_FAULT_OOM;
- pmd = pmd_alloc(mm, pud, address);
+ pmd = pt_share_pmd(vma, address, pud);
if (!pmd)
return VM_FAULT_OOM;
- pte = pte_alloc_map(mm, pmd, address);
+ pte = pt_share_pte(vma, address, pmd);
if (!pte)
return VM_FAULT_OOM;
@@ -2326,13 +2345,17 @@ int __pmd_alloc(struct mm_struct *mm, pu
#ifndef __ARCH_HAS_4LEVEL_HACK
if (pud_present(*pud)) /* Another has populated it */
pmd_free(new);
- else
+ else {
+ pmd_lock_init(new);
pud_populate(mm, pud, new);
+ }
#else
if (pgd_present(*pud)) /* Another has populated it */
pmd_free(new);
- else
+ else {
+ pmd_lock_init(new);
pgd_populate(mm, pud, new);
+ }
#endif /* __ARCH_HAS_4LEVEL_HACK */
spin_unlock(&mm->page_table_lock);
return 0;
--- 2.6.17-rc1-macro/./mm/mmap.c 2006-04-02 22:22:10.000000000 -0500
+++ 2.6.17-rc1-shpt/./mm/mmap.c 2006-04-10 08:46:01.000000000 -0500
@@ -1706,6 +1706,8 @@ int split_vma(struct mm_struct * mm, str
/* most fields are the same, copy all, and then fixup */
*new = *vma;
+ new->vm_flags &= ~VM_TRANSITION;
+
if (new_below)
new->vm_end = addr;
else {
@@ -1941,7 +1943,6 @@ void exit_mmap(struct mm_struct *mm)
while (vma)
vma = remove_vma(vma);
- BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
}
/* Insert vm structure into process list sorted by address
--- 2.6.17-rc1-macro/./mm/mprotect.c 2006-04-02 22:22:10.000000000 -0500
+++ 2.6.17-rc1-shpt/./mm/mprotect.c 2006-04-10 08:46:01.000000000 -0500
@@ -19,6 +19,7 @@
#include <linux/mempolicy.h>
#include <linux/personality.h>
#include <linux/syscalls.h>
+#include <linux/ptshare.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
@@ -115,6 +116,10 @@ mprotect_fixup(struct vm_area_struct *vm
return 0;
}
+ vma->vm_flags |= VM_TRANSITION;
+ if (pt_vmashared(vma))
+ pt_unshare_range(vma, start, end);
+
/*
* If we make a private mapping writable we increase our commit;
* but (without finer accounting) cannot reduce our commit if we
@@ -126,8 +131,10 @@ mprotect_fixup(struct vm_area_struct *vm
if (newflags & VM_WRITE) {
if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_SHARED))) {
charged = nrpages;
- if (security_vm_enough_memory(charged))
+ if (security_vm_enough_memory(charged)) {
+ vma->vm_flags &= ~VM_TRANSITION;
return -ENOMEM;
+ }
newflags |= VM_ACCOUNT;
}
}
@@ -175,6 +182,7 @@ success:
return 0;
fail:
+ vma->vm_flags &= ~VM_TRANSITION;
vm_unacct_memory(charged);
return error;
}
--- 2.6.17-rc1-macro/./mm/mremap.c 2006-04-02 22:22:10.000000000 -0500
+++ 2.6.17-rc1-shpt/./mm/mremap.c 2006-04-10 08:46:01.000000000 -0500
@@ -18,6 +18,7 @@
#include <linux/highmem.h>
#include <linux/security.h>
#include <linux/syscalls.h>
+#include <linux/ptshare.h>
#include <asm/uaccess.h>
#include <asm/cacheflush.h>
@@ -178,6 +179,10 @@ static unsigned long move_vma(struct vm_
if (!new_vma)
return -ENOMEM;
+ vma->vm_flags |= VM_TRANSITION;
+ if (pt_vmashared(vma))
+ pt_unshare_range(vma, old_addr, old_addr + old_len);
+
moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len);
if (moved_len < old_len) {
/*
@@ -221,6 +226,8 @@ static unsigned long move_vma(struct vm_
}
mm->hiwater_vm = hiwater_vm;
+ vma->vm_flags &= ~VM_TRANSITION;
+
/* Restore VM_ACCOUNT if one or two pieces of vma left */
if (excess) {
vma->vm_flags |= VM_ACCOUNT;
--- 2.6.17-rc1-macro/./mm/rmap.c 2006-04-02 22:22:10.000000000 -0500
+++ 2.6.17-rc1-shpt/./mm/rmap.c 2006-04-10 08:46:01.000000000 -0500
@@ -53,6 +53,7 @@
#include <linux/rmap.h>
#include <linux/rcupdate.h>
#include <linux/module.h>
+#include <linux/ptshare.h>
#include <asm/tlbflush.h>
@@ -286,7 +287,8 @@ unsigned long page_address_in_vma(struct
* On success returns with pte mapped and locked.
*/
pte_t *page_check_address(struct page *page, struct mm_struct *mm,
- unsigned long address, spinlock_t **ptlp)
+ unsigned long address, spinlock_t **ptlp,
+ int *shared)
{
pgd_t *pgd;
pud_t *pud;
@@ -306,6 +308,9 @@ pte_t *page_check_address(struct page *p
if (!pmd_present(*pmd))
return NULL;
+ if (pt_is_shared_pmd(*pud))
+ *shared++;
+
pte = pte_offset_map(pmd, address);
/* Make a quick check before getting the lock */
if (!pte_present(*pte)) {
@@ -313,6 +318,9 @@ pte_t *page_check_address(struct page *p
return NULL;
}
+ if (pt_is_shared_pte(*pmd))
+ *shared++;
+
ptl = pte_lockptr(mm, pmd);
spin_lock(ptl);
if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) {
@@ -333,6 +341,7 @@ static int page_referenced_one(struct pa
struct mm_struct *mm = vma->vm_mm;
unsigned long address;
pte_t *pte;
+ int shared;
spinlock_t *ptl;
int referenced = 0;
@@ -340,7 +349,7 @@ static int page_referenced_one(struct pa
if (address == -EFAULT)
goto out;
- pte = page_check_address(page, mm, address, &ptl);
+ pte = page_check_address(page, mm, address, &ptl, &shared);
if (!pte)
goto out;
@@ -584,6 +593,7 @@ static int try_to_unmap_one(struct page
unsigned long address;
pte_t *pte;
pte_t pteval;
+ int shared = 0;
spinlock_t *ptl;
int ret = SWAP_AGAIN;
@@ -591,7 +601,7 @@ static int try_to_unmap_one(struct page
if (address == -EFAULT)
goto out;
- pte = page_check_address(page, mm, address, &ptl);
+ pte = page_check_address(page, mm, address, &ptl, &shared);
if (!pte)
goto out;
@@ -609,7 +619,10 @@ static int try_to_unmap_one(struct page
/* Nuke the page table entry. */
flush_cache_page(vma, address, page_to_pfn(page));
- pteval = ptep_clear_flush(vma, address, pte);
+ if (shared)
+ pteval = ptep_clear_flush_all(vma, address, pte);
+ else
+ pteval = ptep_clear_flush(vma, address, pte);
/* Move the dirty bit to the physical page now the pte is gone. */
if (pte_dirty(pteval))
--- 2.6.17-rc1-macro/./mm/ptshare.c 1969-12-31 18:00:00.000000000 -0600
+++ 2.6.17-rc1-shpt/./mm/ptshare.c 2006-04-10 08:46:01.000000000 -0500
@@ -0,0 +1,463 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2005
+ *
+ * Author: Dave McCracken <dmccr@xxxxxxxxxx>
+ */
+
+#include <linux/kernel.h>
+#include <linux/prio_tree.h>
+#include <linux/mm.h>
+#include <linux/ptshare.h>
+
+#include <asm/tlbflush.h>
+#include <asm/pgtable.h>
+#include <asm/pgalloc.h>
+
+#define VM_PGEND(vma) (((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) -1)
+
+#define VMFLAG_COMPARE (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)
+
+static int pt_shareable_vma(struct vm_area_struct *vma)
+{
+ /* We can't share anonymous memory */
+ if (!vma->vm_file)
+ return 0;
+
+ /* No sharing of nonlinear areas or vmas in transition */
+ if (vma->vm_flags & (VM_NONLINEAR|VM_TRANSITION|VM_PFNMAP|VM_INSERTPAGE))
+ return 0;
+
+ /* Only share shared mappings or read-only mappings */
+ if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) == VM_WRITE)
+ return 0;
+
+ /* If it's smaller than the smallest shareable unit, don't bother
+ calling it shareable */
+ if ((vma->vm_end - vma->vm_start) < PMD_SIZE)
+ return 0;
+
+ return 1;
+}
+
+#ifdef CONFIG_PTSHARE_PTE
+static inline void pt_unshare_pte(struct mm_struct *mm, pmd_t *pmd,
+ unsigned long address)
+{
+ struct page *page;
+ spinlock_t *ptl;
+
+ if (pmd_present(*pmd)) {
+ page = pmd_page(*pmd);
+ ptl = __pt_lockptr(page);
+ spin_lock(ptl);
+ if (pt_is_shared(page)) {
+#ifdef PT_DEBUG
+ printk(KERN_DEBUG "Unsharing pte page at address 0x%lx\n",
+ address);
+#endif
+ pt_decrement_share(page);
+ pmd_clear_flush(mm, address, pmd);
+ }
+ spin_unlock(ptl);
+ }
+}
+#endif
+
+#ifndef __PAGETABLE_PMD_FOLDED
+static void pt_unshare_pmd(struct mm_struct *mm, pud_t *pud, unsigned long address,
+ unsigned long end, int hugepage)
+{
+ if (!pud_present(*pud))
+ return;
+
+#ifdef CONFIG_PTSHARE_PMD
+ {
+ struct page *page;
+ spinlock_t *ptl;
+
+ page = pud_page(*pud);
+ ptl = __pt_lockptr(page);
+ spin_lock(ptl);
+ if (pt_is_shared(page)) {
+#ifdef PT_DEBUG
+ printk(KERN_DEBUG "Unsharing pmd page at address 0x%lx\n",
+ address);
+#endif
+ pt_decrement_share(page);
+ spin_unlock(ptl);
+ pud_clear_flush(mm, address, pud);
+ return;
+ }
+ spin_unlock(ptl);
+ }
+#endif
+#ifdef CONFIG_PTSHARE_PTE
+ if (hugepage)
+ return;
+
+ {
+ pmd_t *pmd;
+
+ pmd = pmd_offset(pud, address);
+ end = pud_addr_end(address, end);
+ while (address <= end) {
+ pt_unshare_pte(mm, pmd, address);
+ pmd++;
+ address += PMD_SIZE;
+ }
+ }
+#endif
+}
+
+#ifndef __PAGETABLE_PUD_FOLDED
+static void pt_unshare_pud(struct mm_struct *mm, pgd_t *pgd, unsigned long address,
+ unsigned long end, int hugepage)
+{
+ pud_t *pud;
+
+ if (!pgd_present(*pgd))
+ return;
+
+ pud = pud_offset(pgd, address);
+ end = pgd_addr_end(address, end);
+ while (address <= end) {
+ pt_unshare_pmd(mm, pud, address, end, hugepage);
+ pud++;
+ address += PUD_SIZE;
+ }
+}
+#endif /* __PAGETABLE_PUD_FOLDED */
+#endif /* __PAGETABLE_PMD_FOLDED */
+
+static void pt_unshare_pgd(struct mm_struct *mm, unsigned long address,
+ unsigned long end, int hugepage)
+{
+ pgd_t *pgd;
+
+ pgd = pgd_offset(mm, address);
+
+ spin_lock(&mm->page_table_lock);
+ while (address <= end) {
+#ifdef __PAGETABLE_PMD_FOLDED
+ if (!hugepage)
+ pt_unshare_pte(mm, (pmd_t *)pgd, address);
+#else
+#ifdef __PAGETABLE_PUD_FOLDED
+ pt_unshare_pmd(mm, (pud_t *)pgd, address, end, hugepage);
+#else
+ pt_unshare_pud(mm, pgd, address, end, hugepage);
+#endif
+#endif
+ pgd++;
+ address += PGDIR_SIZE;
+ }
+ spin_unlock(&mm->page_table_lock);
+}
+
+void pt_unshare_range(struct vm_area_struct *vma, unsigned long address,
+ unsigned long end)
+{
+ struct address_space *mapping;
+
+ mapping = vma->vm_file->f_dentry->d_inode->i_mapping;
+ spin_lock(&mapping->i_mmap_lock);
+
+ pt_unshare_pgd(vma->vm_mm, address, end, 0);
+
+ spin_unlock(&mapping->i_mmap_lock);
+
+ /* If we unshare the entire vma it's safe to clear the share flag */
+ if (vma->vm_start == address &&
+ vma->vm_end == end)
+ vma->vm_flags &= ~VM_PTSHARE;
+}
+
+static struct vm_area_struct *next_shareable_vma(struct vm_area_struct *vma,
+ struct vm_area_struct *svma,
+ struct prio_tree_iter *iter)
+{
+ while ((svma = vma_prio_tree_next(svma, iter))) {
+ if ((svma != vma) &&
+ ((vma->vm_flags&VMFLAG_COMPARE) == (svma->vm_flags&VMFLAG_COMPARE)) &&
+ (vma->vm_start == svma->vm_start) &&
+ (vma->vm_end == svma->vm_end) &&
+ (vma->vm_pgoff == svma->vm_pgoff))
+ break;
+ }
+ return svma;
+}
+
+#ifdef CONFIG_PTSHARE_PTE
+static int pt_shareable_pte(struct vm_area_struct *vma, unsigned long address)
+{
+ unsigned long base = address & PMD_MASK;
+ unsigned long end = base + (PMD_SIZE-1);
+
+ if (pt_shareable_vma(vma) &&
+ (vma->vm_start <= base) &&
+ (vma->vm_end >= end))
+ return 1;
+
+ return 0;
+}
+
+pte_t *pt_share_pte(struct vm_area_struct *vma, unsigned long address, pmd_t *pmd)
+{
+ struct prio_tree_iter iter;
+ struct vm_area_struct *svma = NULL;
+ pgd_t *spgd, spgde;
+ pud_t *spud, spude;
+ pmd_t *spmd, spmde;
+ pte_t *pte;
+ struct page *page;
+ struct address_space *mapping;
+ spinlock_t *ptl;
+
+ pmd_clear(&spmde);
+ page = NULL;
+ if (pmd_none(*pmd) &&
+ pt_shareable_pte(vma, address)) {
+#ifdef PT_DEBUG
+ printk(KERN_DEBUG "Looking for shareable pte page at address 0x%lx\n",
+ address);
+#endif
+ mapping = vma->vm_file->f_dentry->d_inode->i_mapping;
+ spin_lock(&mapping->i_mmap_lock);
+ prio_tree_iter_init(&iter, &mapping->i_mmap,
+ vma->vm_pgoff, VM_PGEND(vma));
+
+ while ((svma = next_shareable_vma(vma, svma, &iter))) {
+ spgd = pgd_offset(svma->vm_mm, address);
+ spgde = *spgd;
+ if (pgd_none(spgde))
+ continue;
+
+ spud = pud_offset(&spgde, address);
+ spude = *spud;
+ if (pud_none(spude))
+ continue;
+
+ spmd = pmd_offset(&spude, address);
+ spmde = *spmd;
+ if (pmd_none(spmde))
+ continue;
+
+ /* Found a shareable page */
+ page = pmd_page(spmde);
+ pt_increment_share(page);
+ break;
+ }
+ spin_unlock(&mapping->i_mmap_lock);
+ if (pmd_present(spmde)) {
+ ptl = pmd_lockptr(vma->vm_mm, pmd);
+ spin_lock(ptl);
+ if (pmd_none(*pmd)) {
+#ifdef PT_DEBUG
+ printk(KERN_DEBUG "Sharing pte page at address 0x%lx\n",
+ address);
+#endif
+ pmd_populate(vma->vm_mm, pmd, page);
+ /* Both vmas now have shared pt */
+ vma->vm_flags |= VM_PTSHARE;
+ svma->vm_flags |= VM_PTSHARE;
+ } else {
+ /* Oops, already mapped... undo it */
+ pt_decrement_share(page);
+ }
+ spin_unlock(ptl);
+ }
+
+ }
+ pte = pte_alloc_map(vma->vm_mm, pmd, address);
+
+ return pte;
+}
+int pt_check_unshare_pte(struct mm_struct *mm, unsigned long address, pmd_t *pmd)
+{
+ struct page *page;
+ spinlock_t *ptl;
+
+ page = pmd_page(*pmd);
+ ptl = __pt_lockptr(page);
+ spin_lock(ptl);
+ /* Doublecheck now that we hold the lock */
+ if (pt_is_shared(page)) {
+#ifdef PT_DEBUG
+ printk(KERN_DEBUG "Unsharing pte at address 0x%lx\n",
+ address);
+#endif
+ pt_decrement_share(page);
+ spin_unlock(ptl);
+ pmd_clear_flush(mm, address, pmd);
+ return 1;
+ }
+ spin_unlock(ptl);
+ return 0;
+}
+#endif
+
+#ifdef CONFIG_PTSHARE_PMD
+static int pt_shareable_pmd(struct vm_area_struct *vma,
+ unsigned long address)
+{
+ unsigned long base = address & PUD_MASK;
+ unsigned long end = base + (PUD_SIZE-1);
+
+ if (pt_shareable_vma(vma) &&
+ (vma->vm_start <= base) &&
+ (vma->vm_end >= end))
+ return 1;
+
+ return 0;
+}
+
+pmd_t *pt_share_pmd(struct vm_area_struct *vma, unsigned long address, pud_t *pud)
+{
+ struct prio_tree_iter iter;
+ struct mm_struct *mm = vma->vm_mm;
+ struct vm_area_struct *svma = NULL;
+ pgd_t *spgd, spgde;
+ pud_t *spud, spude;
+ pmd_t *pmd;
+ struct page *page;
+ struct address_space *mapping;
+
+ pud_clear(&spude);
+ page = NULL;
+ if (pud_none(*pud) &&
+ pt_shareable_pmd(vma, address)) {
+#ifdef PT_DEBUG
+ printk(KERN_DEBUG "Looking for shareable pmd page at address 0x%lx\n",
+ address);
+#endif
+ mapping = vma->vm_file->f_dentry->d_inode->i_mapping;
+
+ spin_lock(&mapping->i_mmap_lock);
+ prio_tree_iter_init(&iter, &mapping->i_mmap,
+ vma->vm_pgoff, VM_PGEND(vma));
+
+ while ((svma = next_shareable_vma(vma, svma, &iter))) {
+ spgd = pgd_offset(svma->vm_mm, address);
+ spgde = *spgd;
+ if (pgd_none(spgde))
+ continue;
+
+ spud = pud_offset(spgd, address);
+ spude = *spud;
+ if (pud_none(spude))
+ continue;
+
+ /* Found a shareable page */
+ page = pud_page(spude);
+ pt_increment_share(page);
+ break;
+ }
+ spin_unlock(&mapping->i_mmap_lock);
+ if (pud_present(spude)) {
+ spin_lock(&mm->page_table_lock);
+ if (pud_none(*pud)) {
+#ifdef PT_DEBUG
+ printk(KERN_DEBUG "Sharing pmd page at address 0x%lx\n",
+ address);
+#endif
+ pud_populate(mm, pud,
+ (pmd_t *)pud_page_kernel(spude));
+ /* These vmas now have shared pt */
+ vma->vm_flags |= VM_PTSHARE;
+ svma->vm_flags |= VM_PTSHARE;
+ } else {
+ /* Oops, already mapped... undo it */
+ pt_decrement_share(page);
+ }
+ spin_unlock(&mm->page_table_lock);
+ }
+ }
+ pmd = pmd_alloc(mm, pud, address);
+
+ return pmd;
+}
+int pt_check_unshare_pmd(struct mm_struct *mm, unsigned long address, pud_t *pud)
+{
+ struct page *page;
+ spinlock_t *ptl;
+
+ page = pud_page(*pud);
+ ptl = __pt_lockptr(page);
+ spin_lock(ptl);
+ /* Doublecheck now that we hold the lock */
+ if (pt_is_shared(page)) {
+#ifdef PT_DEBUG
+ printk(KERN_DEBUG "Unsharing pmd at address 0x%lx\n",
+ address);
+#endif
+ pt_decrement_share(page);
+ spin_unlock(ptl);
+ pud_clear_flush(mm, address, pud);
+ return 1;
+ }
+ spin_unlock(ptl);
+ return 0;
+}
+#endif
+
+#ifdef CONFIG_PTSHARE_HUGEPAGE
+
+void pt_unshare_huge_range(struct vm_area_struct *vma, unsigned long address,
+ unsigned long end)
+{
+ struct address_space *mapping;
+
+ mapping = vma->vm_file->f_dentry->d_inode->i_mapping;
+ spin_lock(&mapping->i_mmap_lock);
+
+#ifdef CONFIG_PTSHARE_HUGEPAGE_PTE
+ pt_unshare_pgd(vma->vm_mm, address, end, 0);
+#else
+ pt_unshare_pgd(vma->vm_mm, address, end, 1);
+#endif
+
+ spin_unlock(&mapping->i_mmap_lock);
+
+ /* If we unshare the entire vma it's safe to clear the share flag */
+ if (vma->vm_start >= address &&
+ vma->vm_end <= end)
+ vma->vm_flags &= ~VM_PTSHARE;
+}
+
+pte_t *pt_share_hugepage(struct mm_struct *mm, struct vm_area_struct *vma,
+ unsigned long address)
+{
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+
+ pgd = pgd_offset(mm, address);
+ pud = pud_alloc(mm, pgd, address);
+ if (!pud)
+ return VM_FAULT_OOM;
+ pmd = pt_share_pmd(vma, address, pud);
+ if (!pmd)
+ return VM_FAULT_OOM;
+#ifdef CONFIG_PTSHARE_HUGEPAGE_PTE
+ pte = pt_share_pte(vma, address, pmd);
+#else
+ pte = (pte_t *)pmd;
+#endif
+ return pte;
+}
+#endif
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