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Subject[PATCH 2/2] Simple shared page tables
The actual shared page table patches

------------------------
Diffstat:

arch/i386/Kconfig | 7
arch/s390/Kconfig | 7
arch/x86_64/Kconfig | 7
fs/proc/proc_misc.c | 6
fs/proc/task_mmu.c | 7
include/asm-generic/pgtable.h | 31 +++
include/linux/mm.h | 10 -
include/linux/mmzone.h | 3
include/linux/ptshare.h | 69 ++++++++
include/linux/rmap.h | 2
include/linux/sched.h | 5
mm/Makefile | 1
mm/filemap_xip.c | 3
mm/fremap.c | 3
mm/memory.c | 8 -
mm/mmap.c | 7
mm/mprotect.c | 8 -
mm/mremap.c | 3
mm/ptshare.c | 332 ++++++++++++++++++++++++++++++++++++++++++
mm/rmap.c | 18 +-
mm/vmstat.c | 3
21 files changed, 524 insertions(+), 16 deletions(-)
------------------------
--- 2.6.18-rc4-macro/./arch/i386/Kconfig 2006-08-06 13:20:11.000000000 -0500
+++ 2.6.18-rc4-shpt/./arch/i386/Kconfig 2006-08-07 19:28:56.000000000 -0500
@@ -539,6 +539,13 @@ config X86_PAE
default y
select RESOURCES_64BIT

+config PTSHARE
+ bool "Share page tables"
+ default y
+ help
+ Turn on sharing of page tables between processes for large shared
+ memory regions.
+
# Common NUMA Features
config NUMA
bool "Numa Memory Allocation and Scheduler Support"
--- 2.6.18-rc4-macro/./arch/s390/Kconfig 2006-08-06 13:20:11.000000000 -0500
+++ 2.6.18-rc4-shpt/./arch/s390/Kconfig 2006-08-07 19:28:56.000000000 -0500
@@ -219,6 +219,13 @@ 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.
+
comment "I/O subsystem configuration"

config MACHCHK_WARNING
--- 2.6.18-rc4-macro/./arch/x86_64/Kconfig 2006-08-06 13:20:11.000000000 -0500
+++ 2.6.18-rc4-shpt/./arch/x86_64/Kconfig 2006-08-07 19:28:56.000000000 -0500
@@ -321,6 +321,13 @@ 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 ARCH_DISCONTIGMEM_ENABLE
bool
depends on NUMA
--- 2.6.18-rc4-macro/./fs/proc/proc_misc.c 2006-08-06 13:20:11.000000000 -0500
+++ 2.6.18-rc4-shpt/./fs/proc/proc_misc.c 2006-08-15 10:15:09.000000000 -0500
@@ -169,6 +169,9 @@ static int meminfo_read_proc(char *page,
"Mapped: %8lu kB\n"
"Slab: %8lu kB\n"
"PageTables: %8lu kB\n"
+#ifdef CONFIG_PTSHARE
+ "SharedPTE: %8lu kB\n"
+#endif
"NFS Unstable: %8lu kB\n"
"Bounce: %8lu kB\n"
"CommitLimit: %8lu kB\n"
@@ -195,6 +198,9 @@ static int meminfo_read_proc(char *page,
K(global_page_state(NR_FILE_MAPPED)),
K(global_page_state(NR_SLAB)),
K(global_page_state(NR_PAGETABLE)),
+#ifdef CONFIG_PTSHARE
+ K(global_page_state(NR_SHAREDPTE)),
+#endif
K(global_page_state(NR_UNSTABLE_NFS)),
K(global_page_state(NR_BOUNCE)),
K(allowed),
--- 2.6.18-rc4-macro/./fs/proc/task_mmu.c 2006-08-06 13:20:11.000000000 -0500
+++ 2.6.18-rc4-shpt/./fs/proc/task_mmu.c 2006-08-15 15:41:06.000000000 -0500
@@ -43,6 +43,9 @@ char *task_mem(struct mm_struct *mm, cha
"VmStk:\t%8lu kB\n"
"VmExe:\t%8lu kB\n"
"VmLib:\t%8lu kB\n"
+#ifdef CONFIG_PTSHARE
+ "VmSHPT:\t%8lu kB\n"
+#endif
"VmPTE:\t%8lu kB\n",
hiwater_vm << (PAGE_SHIFT-10),
(total_vm - mm->reserved_vm) << (PAGE_SHIFT-10),
@@ -51,7 +54,11 @@ char *task_mem(struct mm_struct *mm, cha
total_rss << (PAGE_SHIFT-10),
data << (PAGE_SHIFT-10),
mm->stack_vm << (PAGE_SHIFT-10), text, lib,
+#ifdef CONFIG_PTSHARE
+ (PTRS_PER_PTE*sizeof(pte_t)*mm->nr_shpte) >> 10,
+#endif
(PTRS_PER_PTE*sizeof(pte_t)*mm->nr_ptes) >> 10);
+
return buffer;
}

--- 2.6.18-rc4-macro/./include/asm-generic/pgtable.h 2006-08-06 13:20:11.000000000 -0500
+++ 2.6.18-rc4-shpt/./include/asm-generic/pgtable.h 2006-08-07 19:28:56.000000000 -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)
@@ -164,6 +174,27 @@ 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.
--- 2.6.18-rc4-macro/./include/linux/mm.h 2006-08-06 13:20:11.000000000 -0500
+++ 2.6.18-rc4-shpt/./include/linux/mm.h 2006-08-07 19:28:56.000000000 -0500
@@ -245,7 +245,7 @@ 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
};
@@ -826,19 +826,19 @@ 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.
--- 2.6.18-rc4-macro/./include/linux/mmzone.h 2006-08-06 13:20:11.000000000 -0500
+++ 2.6.18-rc4-shpt/./include/linux/mmzone.h 2006-08-15 10:14:04.000000000 -0500
@@ -65,6 +65,9 @@ enum zone_stat_item {
NUMA_LOCAL, /* allocation from local node */
NUMA_OTHER, /* allocation from other node */
#endif
+#ifdef CONFIG_PTSHARE
+ NR_SHAREDPTE, /* Number of shared page table pages */
+#endif
NR_VM_ZONE_STAT_ITEMS };

struct per_cpu_pages {
--- 2.6.18-rc4-macro/./include/linux/rmap.h 2006-08-06 13:20:11.000000000 -0500
+++ 2.6.18-rc4-shpt/./include/linux/rmap.h 2006-08-07 19:28:56.000000000 -0500
@@ -96,7 +96,7 @@ int try_to_unmap(struct page *, int igno
* 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.
--- 2.6.18-rc4-macro/./include/linux/sched.h 2006-08-06 13:20:11.000000000 -0500
+++ 2.6.18-rc4-shpt/./include/linux/sched.h 2006-08-15 14:05:41.000000000 -0500
@@ -257,7 +257,7 @@ 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.
@@ -333,6 +333,9 @@ struct mm_struct {
unsigned long start_code, end_code, start_data, end_data;
unsigned long start_brk, brk, start_stack;
unsigned long arg_start, arg_end, env_start, env_end;
+#ifdef CONFIG_PTSHARE
+ unsigned long nr_shpte;
+#endif

unsigned long saved_auxv[AT_VECTOR_SIZE]; /* for /proc/PID/auxv */

--- 2.6.18-rc4-macro/./include/linux/ptshare.h 1969-12-31 18:00:00.000000000 -0600
+++ 2.6.18-rc4-shpt/./include/linux/ptshare.h 2006-08-07 19:57:56.000000000 -0500
@@ -0,0 +1,69 @@
+#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@us.ibm.com>
+ */
+
+#undef PT_DEBUG
+
+#ifdef CONFIG_PTSHARE
+static inline int pt_is_shared(struct page *page)
+{
+ return (page_mapcount(page) > 0);
+}
+
+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_share(struct page *page)
+{
+ atomic_inc(&page->_mapcount);
+}
+
+static inline void pt_decrement_share(struct page *page)
+{
+ atomic_dec(&page->_mapcount);
+}
+
+extern pte_t *pt_share_pte(struct vm_area_struct *vma, pmd_t *pmd,
+ unsigned long address);
+
+extern void pt_unshare_range(struct mm_struct *mm, unsigned long address,
+ unsigned long end);
+
+extern int pt_check_unshare_pte(struct mm_struct *mm, unsigned long address,
+ pmd_t *pmd);
+
+#else /* CONFIG_PTSHARE */
+#define pt_is_shared(page) (0)
+#define pt_is_shared_pte(pmdval) (0)
+#define pt_increment_share(page)
+#define pt_decrement_share(page)
+#define pt_share_pte(vma, pmd, address) pte_alloc_map(vma->vm_mm, pmd, address)
+#define pt_unshare_range(mm, address, end)
+#define pt_check_unshare_pte(mm, address, pmd) (0)
+#endif /* CONFIG_PTSHARE */
+
+#endif /* _LINUX_PTSHARE_H */
--- 2.6.18-rc4-macro/./mm/Makefile 2006-08-06 13:20:11.000000000 -0500
+++ 2.6.18-rc4-shpt/./mm/Makefile 2006-08-07 19:28:56.000000000 -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

--- 2.6.18-rc4-macro/./mm/filemap_xip.c 2006-08-06 13:20:11.000000000 -0500
+++ 2.6.18-rc4-shpt/./mm/filemap_xip.c 2006-08-07 19:28:56.000000000 -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));
--- 2.6.18-rc4-macro/./mm/fremap.c 2006-08-06 13:20:11.000000000 -0500
+++ 2.6.18-rc4-shpt/./mm/fremap.c 2006-08-07 19:28:56.000000000 -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>
@@ -200,6 +201,8 @@ asmlinkage long sys_remap_file_pages(uns
has_write_lock = 1;
goto retry;
}
+ pt_unshare_range(mm, vma->vm_start, vma->vm_end);
+
mapping = vma->vm_file->f_mapping;
spin_lock(&mapping->i_mmap_lock);
flush_dcache_mmap_lock(mapping);
--- 2.6.18-rc4-macro/./mm/memory.c 2006-08-06 13:20:11.000000000 -0500
+++ 2.6.18-rc4-shpt/./mm/memory.c 2006-08-15 15:13:51.000000000 -0500
@@ -49,6 +49,7 @@
#include <linux/module.h>
#include <linux/delayacct.h>
#include <linux/init.h>
+#include <linux/ptshare.h>

#include <asm/pgalloc.h>
#include <asm/uaccess.h>
@@ -145,6 +146,8 @@ static inline void free_pmd_range(struct
next = pmd_addr_end(addr, end);
if (pmd_none_or_clear_bad(pmd))
continue;
+ if (pt_check_unshare_pte(tlb->mm, addr, pmd))
+ continue;
free_pte_range(tlb, pmd);
} while (pmd++, addr = next, addr != end);

@@ -626,6 +629,9 @@ static unsigned long zap_pte_range(struc
int file_rss = 0;
int anon_rss = 0;

+ if (pt_check_unshare_pte(mm, addr, pmd))
+ return end;
+
pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
do {
pte_t ptent = *pte;
@@ -2340,7 +2346,7 @@ int __handle_mm_fault(struct mm_struct *
pmd = pmd_alloc(mm, pud, address);
if (!pmd)
return VM_FAULT_OOM;
- pte = pte_alloc_map(mm, pmd, address);
+ pte = pt_share_pte(vma, pmd, address);
if (!pte)
return VM_FAULT_OOM;

--- 2.6.18-rc4-macro/./mm/mmap.c 2006-08-06 13:20:11.000000000 -0500
+++ 2.6.18-rc4-shpt/./mm/mmap.c 2006-08-07 19:34:05.000000000 -0500
@@ -25,6 +25,7 @@
#include <linux/mount.h>
#include <linux/mempolicy.h>
#include <linux/rmap.h>
+#include <linux/ptshare.h>

#include <asm/uaccess.h>
#include <asm/cacheflush.h>
@@ -1039,6 +1040,7 @@ munmap_back:
vm_flags |= VM_ACCOUNT;
}
}
+ pt_unshare_range(mm, addr, addr + len);

/*
* Can we just expand an old private anonymous mapping?
@@ -1950,6 +1952,9 @@ void exit_mmap(struct mm_struct *mm)
unsigned long nr_accounted = 0;
unsigned long end;

+ /* We need this semaphore to protect against page table sharing */
+ down_write(&mm->mmap_sem);
+
lru_add_drain();
flush_cache_mm(mm);
tlb = tlb_gather_mmu(mm, 1);
@@ -1959,6 +1964,7 @@ void exit_mmap(struct mm_struct *mm)
vm_unacct_memory(nr_accounted);
free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);
tlb_finish_mmu(tlb, 0, end);
+ up_write(&mm->mmap_sem);

/*
* Walk the list again, actually closing and freeing it,
@@ -1967,7 +1973,6 @@ 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
--- 2.6.18-rc4-macro/./mm/mprotect.c 2006-08-06 13:20:11.000000000 -0500
+++ 2.6.18-rc4-shpt/./mm/mprotect.c 2006-08-07 19:28:56.000000000 -0500
@@ -21,6 +21,7 @@
#include <linux/syscalls.h>
#include <linux/swap.h>
#include <linux/swapops.h>
+#include <linux/ptshare.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/cacheflush.h>
@@ -133,6 +134,8 @@ mprotect_fixup(struct vm_area_struct *vm
return 0;
}

+ pt_unshare_range(mm, start, end);
+
/*
* If we make a private mapping writable we increase our commit;
* but (without finer accounting) cannot reduce our commit if we
@@ -144,8 +147,9 @@ 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)) {
return -ENOMEM;
+ }
newflags |= VM_ACCOUNT;
}
}
@@ -182,7 +186,7 @@ success:
if (vma->vm_ops && vma->vm_ops->page_mkwrite)
mask &= ~VM_SHARED;

- newprot = protection_map[newflags & mask];
+ newprot = protection_map[newflags & mask];

/*
* vm_flags and vm_page_prot are protected by the mmap_sem
--- 2.6.18-rc4-macro/./mm/mremap.c 2006-08-06 13:20:11.000000000 -0500
+++ 2.6.18-rc4-shpt/./mm/mremap.c 2006-08-07 19:28:56.000000000 -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 +179,8 @@ static unsigned long move_vma(struct vm_
if (!new_vma)
return -ENOMEM;

+ pt_unshare_range(mm, 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) {
/*
--- 2.6.18-rc4-macro/./mm/rmap.c 2006-08-06 13:20:11.000000000 -0500
+++ 2.6.18-rc4-shpt/./mm/rmap.c 2006-08-07 19:28:56.000000000 -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>

@@ -248,7 +249,8 @@ 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;
@@ -275,6 +277,9 @@ 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)) {
@@ -295,6 +300,7 @@ 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;

@@ -302,7 +308,7 @@ 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;

@@ -547,6 +553,7 @@ 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;

@@ -554,7 +561,7 @@ 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;

@@ -571,7 +578,10 @@ 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))
--- 2.6.18-rc4-macro/./mm/vmstat.c 2006-08-06 13:20:11.000000000 -0500
+++ 2.6.18-rc4-shpt/./mm/vmstat.c 2006-08-15 16:32:59.000000000 -0500
@@ -402,6 +402,9 @@ static char *vmstat_text[] = {
"numa_local",
"numa_other",
#endif
+#ifdef CONFIG_PTSHARE
+ "nr_sharedpte",
+#endif

#ifdef CONFIG_VM_EVENT_COUNTERS
"pgpgin",
--- 2.6.18-rc4-macro/./mm/ptshare.c 1969-12-31 18:00:00.000000000 -0600
+++ 2.6.18-rc4-shpt/./mm/ptshare.c 2006-08-15 16:41:49.000000000 -0500
@@ -0,0 +1,332 @@
+/*
+ * 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@us.ibm.com>
+ */
+
+#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)
+
+#undef PT_DEBUG
+
+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 "Force unshare pte for %s[%d] at address 0x%lx\n",
+ current->comm, current->pid, address);
+#endif
+ pt_decrement_share(page);
+ mm->nr_shpte--;
+ mm->nr_ptes--;
+ if (!pt_is_shared(page))
+ dec_zone_page_state(page, NR_SHAREDPTE);
+ pmd_clear_flush(mm, address, pmd);
+ }
+ spin_unlock(ptl);
+ }
+}
+
+#ifndef __PAGETABLE_PMD_FOLDED
+static void pt_unshare_pmd(struct mm_struct *mm, pud_t *pud, unsigned long address,
+ unsigned long end)
+{
+ pmd_t *pmd;
+
+ if (!pud_present(*pud))
+ return;
+
+ pmd = pmd_offset(pud, address);
+ end = pud_addr_end(address, end);
+ while (address < end) {
+ pt_unshare_pte(mm, pmd, address);
+ pmd++;
+ address += PMD_SIZE;
+ }
+}
+
+#ifndef __PAGETABLE_PUD_FOLDED
+static void pt_unshare_pud(struct mm_struct *mm, pgd_t *pgd, unsigned long address,
+ unsigned long end)
+{
+ 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);
+ pud++;
+ address += PUD_SIZE;
+ }
+}
+#endif /* __PAGETABLE_PUD_FOLDED */
+#endif /* __PAGETABLE_PMD_FOLDED */
+
+void pt_unshare_range(struct mm_struct *mm, unsigned long address,
+ unsigned long end)
+{
+ pgd_t *pgd;
+
+ pgd = pgd_offset(mm, address);
+
+ spin_lock(&mm->page_table_lock);
+ while (address < end) {
+#ifdef __PAGETABLE_PMD_FOLDED
+ pt_unshare_pte(mm, (pmd_t *)pgd, address);
+#else
+#ifdef __PAGETABLE_PUD_FOLDED
+ pt_unshare_pmd(mm, (pud_t *)pgd, address, end);
+#else
+ pt_unshare_pud(mm, pgd, address, end);
+#endif
+#endif
+ pgd++;
+ address += PGDIR_SIZE;
+ }
+ spin_unlock(&mm->page_table_lock);
+}
+
+static int pt_shareable_flags(struct vm_area_struct *vma)
+{
+ /* We can't share anonymous memory */
+ if (!vma->vm_file || vma->anon_vma)
+ return 0;
+
+ /* No sharing of nonlinear areas */
+ if (vma->vm_flags & (VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE|VM_HUGETLB))
+ return 0;
+
+ /* Shared mappings are shareable */
+ if (vma->vm_flags & VM_SHARED)
+ return 1;
+
+ /* We can't share if it's writeable or might have been writeable */
+ if (vma->vm_flags & VM_WRITE)
+ return 0;
+
+ /* What's left is read-only, which is shareable */
+ return 1;
+}
+
+static int pt_shareable_range(struct vm_area_struct *vma, unsigned long address,
+ unsigned long mask)
+{
+ unsigned long base = address & mask;
+ unsigned long end = base + ~mask;
+ struct vm_area_struct *prev = vma;
+
+ /* We can share if the vma spans the entire page */
+ if ((vma->vm_start <= base) &&
+ (vma->vm_end > end))
+ return 1;
+
+ /* We can share if the page only contains that vma */
+ while ((vma = vma->vm_next)) {
+ if (vma->vm_start > end)
+ break;
+ /* No access vmas don't count since they don't use the page table */
+ if (vma->vm_flags & (VM_READ|VM_WRITE|VM_EXEC))
+ return 0;
+ }
+ while (1) {
+ vma = prev;
+ BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &prev) != vma);
+ if (!prev)
+ break;
+ if (prev->vm_end < base)
+ break;
+ if (prev->vm_flags & (VM_READ|VM_WRITE|VM_EXEC))
+ return 0;
+ }
+ return 1;
+}
+
+static struct vm_area_struct *next_shareable_vma(struct vm_area_struct *vma,
+ struct vm_area_struct *svma,
+ struct prio_tree_iter *iter)
+{
+ struct mm_struct *smm;
+
+ while ((svma = vma_prio_tree_next(svma, iter))) {
+ if (svma == vma)
+ continue;
+
+ smm = svma->vm_mm;
+ /* Skip this one if the mm is doing something to its vmas */
+ if (unlikely(!down_read_trylock(&smm->mmap_sem)))
+ continue;
+
+ if ((vma->vm_flags&VMFLAG_COMPARE) != (svma->vm_flags&VMFLAG_COMPARE))
+ goto next;
+
+ if ((vma->vm_start != svma->vm_start) ||
+ (vma->vm_end != svma->vm_end) ||
+ (vma->vm_pgoff != svma->vm_pgoff))
+ goto next;
+
+ return svma;
+
+ next:
+ up_read(&smm->mmap_sem);
+ }
+ return NULL;
+}
+
+pte_t *pt_share_pte(struct vm_area_struct *vma, pmd_t *pmd, unsigned long address)
+{
+ struct prio_tree_iter iter;
+ struct mm_struct *mm = vma->vm_mm, *smm;
+ struct vm_area_struct *svma = NULL;
+ pgd_t *spgd, spgde;
+ pud_t *spud, spude;
+ pmd_t *spmd, spmde;
+ pte_t *pte;
+ spinlock_t *ptl = NULL;
+ struct page *page = NULL;
+ struct address_space *mapping;
+ int was_shared;
+
+ pmd_clear(&spmde);
+ if (pmd_none(*pmd) &&
+ pt_shareable_flags(vma) &&
+ pt_shareable_range(vma, address, PMD_MASK)) {
+#ifdef PT_DEBUG2
+ 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))) {
+ smm = svma->vm_mm;
+
+ if (!pt_shareable_range(svma, address, PMD_MASK))
+ goto next;
+
+ spgd = pgd_offset(smm, address);
+ spgde = *spgd;
+ if (!pgd_present(spgde))
+ goto next;
+
+ spud = pud_offset(&spgde, address);
+ spude = *spud;
+ if (!pud_present(spude))
+ goto next;
+
+ spmd = pmd_offset(&spude, address);
+ spmde = *spmd;
+ if (pmd_present(spmde))
+ goto found;
+
+ next:
+ up_read(&smm->mmap_sem);
+ }
+ spin_unlock(&mapping->i_mmap_lock);
+ goto notfound;
+
+found:
+ /* Found a shareable page */
+ spin_lock(&mm->page_table_lock);
+
+ page = pmd_page(spmde);
+ ptl = __pt_lockptr(page);
+ spin_lock(ptl);
+ was_shared = pt_is_shared(page);
+ pt_increment_share(page);
+
+ /* We have the page. Now we can release the locks on the other mm */
+ up_read(&smm->mmap_sem);
+ spin_unlock(&mapping->i_mmap_lock);
+
+ /* Check to make sure no one else filled it already */
+ if (pmd_none(*pmd)) {
+#ifdef PT_DEBUG
+ printk(KERN_DEBUG "Sharing pte for %s[%d] at address 0x%lx\n",
+ current->comm, current->pid, address);
+#endif
+ pmd_populate(mm, pmd, page);
+ mm->nr_shpte++;
+ mm->nr_ptes++;
+ if (!was_shared)
+ inc_zone_page_state(page, NR_SHAREDPTE);
+ } else
+ pt_decrement_share(page);
+
+ spin_unlock(ptl);
+ spin_unlock(&mm->page_table_lock);
+ }
+notfound:
+ pte = pte_alloc_map(mm, pmd, address);
+
+ return pte;
+}
+
+/*
+ * Check whether this pmd entry points to a shared pte page. If it does,
+ * unshare it by removing the entry and decrementing the share count in the
+ * page. This effectively gives away the pte page to whoever else is sharing
+ * it. This process will then allocate a new pte page on the next fault.
+ */
+int pt_check_unshare_pte(struct mm_struct *mm, unsigned long address, pmd_t *pmd)
+{
+ struct page *page;
+ spinlock_t *ptl;
+ int ret = 0;
+
+ page = pmd_page(*pmd);
+ ptl = __pt_lockptr(page);
+ spin_lock(ptl);
+ /* Check under the lock */
+ if (pt_is_shared(page)) {
+#ifdef PT_DEBUG
+ printk(KERN_DEBUG "Unshare pte for %s[%d] at address 0x%lx\n",
+ current->comm, current->pid, address);
+#endif
+ pt_decrement_share(page);
+ mm->nr_shpte--;
+ mm->nr_ptes--;
+ if (!pt_is_shared(page))
+ dec_zone_page_state(page, NR_SHAREDPTE);
+ pmd_clear_flush(mm, address, pmd);
+ ret = 1;
+ }
+ spin_unlock(ptl);
+ return ret;
+}
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  Last update: 2006-08-16 00:59    [from the cache]
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