[patch 1/4] mmu_notifier: Core code
From: Christoph Lameter
Date: Fri Jan 25 2008 - 00:59:31 EST
Core code for mmu notifiers.
Signed-off-by: Christoph Lameter <clameter@xxxxxxx>
Signed-off-by: Andrea Arcangeli <andrea@xxxxxxxxxxxx>
---
include/linux/mm_types.h | 8 ++
include/linux/mmu_notifier.h | 152 +++++++++++++++++++++++++++++++++++++++++++
include/linux/page-flags.h | 9 ++
kernel/fork.c | 2
mm/Kconfig | 4 +
mm/Makefile | 1
mm/mmap.c | 2
mm/mmu_notifier.c | 91 +++++++++++++++++++++++++
8 files changed, 269 insertions(+)
Index: linux-2.6/include/linux/mm_types.h
===================================================================
--- linux-2.6.orig/include/linux/mm_types.h 2008-01-24 20:59:17.000000000 -0800
+++ linux-2.6/include/linux/mm_types.h 2008-01-24 20:59:19.000000000 -0800
@@ -153,6 +153,10 @@ struct vm_area_struct {
#endif
};
+struct mmu_notifier_head {
+ struct hlist_head head;
+};
+
struct mm_struct {
struct vm_area_struct * mmap; /* list of VMAs */
struct rb_root mm_rb;
@@ -219,6 +223,10 @@ struct mm_struct {
/* aio bits */
rwlock_t ioctx_list_lock;
struct kioctx *ioctx_list;
+
+#ifdef CONFIG_MMU_NOTIFIER
+ struct mmu_notifier_head mmu_notifier; /* MMU notifier list */
+#endif
};
#endif /* _LINUX_MM_TYPES_H */
Index: linux-2.6/include/linux/mmu_notifier.h
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6/include/linux/mmu_notifier.h 2008-01-24 20:59:19.000000000 -0800
@@ -0,0 +1,152 @@
+#ifndef _LINUX_MMU_NOTIFIER_H
+#define _LINUX_MMU_NOTIFIER_H
+
+/*
+ * MMU motifier
+ *
+ * Notifier functions for hardware and software that establishes external
+ * references to pages of a Linux system. The notifier calls ensure that
+ * the external mappings are removed when the Linux VM removes memory ranges
+ * or individual pages from a process.
+ *
+ * These fall into two classes
+ *
+ * 1. mmu_notifier
+ *
+ * These are callbacks registered with an mm_struct. If mappings are
+ * removed from an address space then callbacks are performed.
+ * Spinlocks must be held in order to the walk reverse maps and the
+ * notifications are performed while the spinlock is held.
+ *
+ *
+ * 2. mmu_rmap_notifier
+ *
+ * Callbacks for subsystems that provide their own rmaps. These
+ * need to walk their own rmaps for a page. The invalidate_page
+ * callback is outside of locks so that we are not in a strictly
+ * atomic context (but we may be in a PF_MEMALLOC context if the
+ * notifier is called from reclaim code) and are able to sleep.
+ * Rmap notifiers need an extra page bit and are only available
+ * on 64 bit platforms. It is up to the subsystem to mark pags
+ * as PageExternalRmap as needed to trigger the callbacks. Pages
+ * must be marked dirty if dirty bits are set in the external
+ * pte.
+ */
+
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/rcupdate.h>
+#include <linux/mm_types.h>
+
+struct mmu_notifier_ops;
+
+struct mmu_notifier {
+ struct hlist_node hlist;
+ const struct mmu_notifier_ops *ops;
+};
+
+struct mmu_notifier_ops {
+ void (*release)(struct mmu_notifier *mn,
+ struct mm_struct *mm);
+ int (*age_page)(struct mmu_notifier *mn,
+ struct mm_struct *mm,
+ unsigned long address);
+ void (*invalidate_page)(struct mmu_notifier *mn,
+ struct mm_struct *mm,
+ unsigned long address);
+ void (*invalidate_range)(struct mmu_notifier *mn,
+ struct mm_struct *mm,
+ unsigned long start, unsigned long end);
+};
+
+struct mmu_rmap_notifier_ops;
+
+struct mmu_rmap_notifier {
+ struct hlist_node hlist;
+ const struct mmu_rmap_notifier_ops *ops;
+};
+
+struct mmu_rmap_notifier_ops {
+ /*
+ * Called with the page lock held after ptes are modified or removed
+ * so that a subsystem with its own rmap's can remove remote ptes
+ * mapping a page.
+ */
+ void (*invalidate_page)(struct mmu_rmap_notifier *mrn, struct page *page);
+};
+
+#ifdef CONFIG_MMU_NOTIFIER
+
+extern void mmu_notifier_register(struct mmu_notifier *mn,
+ struct mm_struct *mm);
+extern void mmu_notifier_unregister(struct mmu_notifier *mn,
+ struct mm_struct *mm);
+extern void mmu_notifier_release(struct mm_struct *mm);
+extern int mmu_notifier_age_page(struct mm_struct *mm,
+ unsigned long address);
+
+static inline void mmu_notifier_head_init(struct mmu_notifier_head *mnh)
+{
+ INIT_HLIST_HEAD(&mnh->head);
+}
+
+#define mmu_notifier(function, mm, args...) \
+ do { \
+ struct mmu_notifier *__mn; \
+ struct hlist_node *__n; \
+ \
+ if (unlikely(!hlist_empty(&(mm)->mmu_notifier.head))) { \
+ rcu_read_lock(); \
+ hlist_for_each_entry_rcu(__mn, __n, \
+ &(mm)->mmu_notifier.head, \
+ hlist) \
+ if (__mn->ops->function) \
+ __mn->ops->function(__mn, \
+ mm, \
+ args); \
+ rcu_read_unlock(); \
+ } \
+ } while (0)
+
+extern void mmu_rmap_notifier_register(struct mmu_rmap_notifier *mrn);
+extern void mmu_rmap_notifier_unregister(struct mmu_rmap_notifier *mrn);
+
+extern struct hlist_head mmu_rmap_notifier_list;
+
+#define mmu_rmap_notifier(function, args...) \
+ do { \
+ struct mmu_rmap_notifier *__mrn; \
+ struct hlist_node *__n; \
+ \
+ rcu_read_lock(); \
+ hlist_for_each_entry_rcu(__mrn, __n, &mmu_rmap_notifier_list, \
+ hlist) \
+ if (__mrn->ops->function) \
+ __mrn->ops->function(__mrn, args); \
+ rcu_read_unlock(); \
+ } while (0);
+
+#else /* CONFIG_MMU_NOTIFIER */
+
+#define mmu_notifier(function, mm, args...) do { } while (0)
+#define mmu_rmap_notifier(function, args...) do { } while (0)
+
+static inline void mmu_notifier_register(struct mmu_notifier *mn,
+ struct mm_struct *mm) {}
+static inline void mmu_notifier_unregister(struct mmu_notifier *mn,
+ struct mm_struct *mm) {}
+static inline void mmu_notifier_release(struct mm_struct *mm) {}
+static inline void mmu_notifier_age(struct mm_struct *mm,
+ unsigned long address)
+{
+ return 0;
+}
+
+static inline void mmu_notifier_head_init(struct mmu_notifier_head *mmh) {}
+
+static inline void mmu_rmap_notifier_register(struct mmu_rmap_notifier *mrn) {}
+static inline void mmu_rmap_notifier_unregister(struct mmu_rmap_notifier *mrn) {}
+
+#endif /* CONFIG_MMU_NOTIFIER */
+
+#endif /* _LINUX_MMU_NOTIFIER_H */
Index: linux-2.6/include/linux/page-flags.h
===================================================================
--- linux-2.6.orig/include/linux/page-flags.h 2008-01-24 20:59:17.000000000 -0800
+++ linux-2.6/include/linux/page-flags.h 2008-01-24 20:59:19.000000000 -0800
@@ -105,6 +105,7 @@
* 64 bit | FIELDS | ?????? FLAGS |
* 63 32 0
*/
+#define PG_external_rmap 30 /* Page has external rmap */
#define PG_uncached 31 /* Page has been mapped as uncached */
#endif
@@ -260,6 +261,14 @@ static inline void __ClearPageTail(struc
#define SetPageUncached(page) set_bit(PG_uncached, &(page)->flags)
#define ClearPageUncached(page) clear_bit(PG_uncached, &(page)->flags)
+#if defined(CONFIG_MMU_NOTIFIER) && defined(CONFIG_64BIT)
+#define PageExternalRmap(page) test_bit(PG_external_rmap, &(page)->flags)
+#define SetPageExternalRmap(page) set_bit(PG_external_rmap, &(page)->flags)
+#define ClearPageExternalRmap(page) clear_bit(PG_external_rmap, &(page)->flags)
+#else
+#define PageExternalRmap(page) 0
+#endif
+
struct page; /* forward declaration */
extern void cancel_dirty_page(struct page *page, unsigned int account_size);
Index: linux-2.6/mm/Kconfig
===================================================================
--- linux-2.6.orig/mm/Kconfig 2008-01-24 20:59:17.000000000 -0800
+++ linux-2.6/mm/Kconfig 2008-01-24 20:59:19.000000000 -0800
@@ -193,3 +193,7 @@ config NR_QUICK
config VIRT_TO_BUS
def_bool y
depends on !ARCH_NO_VIRT_TO_BUS
+
+config MMU_NOTIFIER
+ def_bool y
+ bool "MMU notifier, for paging KVM/RDMA"
Index: linux-2.6/mm/Makefile
===================================================================
--- linux-2.6.orig/mm/Makefile 2008-01-24 20:59:17.000000000 -0800
+++ linux-2.6/mm/Makefile 2008-01-24 20:59:19.000000000 -0800
@@ -30,4 +30,5 @@ obj-$(CONFIG_FS_XIP) += filemap_xip.o
obj-$(CONFIG_MIGRATION) += migrate.o
obj-$(CONFIG_SMP) += allocpercpu.o
obj-$(CONFIG_QUICKLIST) += quicklist.o
+obj-$(CONFIG_MMU_NOTIFIER) += mmu_notifier.o
Index: linux-2.6/mm/mmu_notifier.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6/mm/mmu_notifier.c 2008-01-24 20:59:19.000000000 -0800
@@ -0,0 +1,91 @@
+/*
+ * linux/mm/mmu_notifier.c
+ *
+ * Copyright (C) 2008 Qumranet, Inc.
+ * Copyright (C) 2008 SGI
+ * Christoph Lameter <clameter@xxxxxxx>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See
+ * the COPYING file in the top-level directory.
+ */
+
+#include <linux/mmu_notifier.h>
+#include <linux/module.h>
+
+void mmu_notifier_release(struct mm_struct *mm)
+{
+ struct mmu_notifier *mn;
+ struct hlist_node *n;
+
+ if (unlikely(!hlist_empty(&mm->mmu_notifier.head))) {
+ rcu_read_lock();
+ hlist_for_each_entry_rcu(mn, n,
+ &mm->mmu_notifier.head, hlist) {
+ if (mn->ops->release)
+ mn->ops->release(mn, mm);
+ hlist_del(&mn->hlist);
+ }
+ rcu_read_unlock();
+ }
+}
+
+/*
+ * If no young bitflag is supported by the hardware, ->age_page can
+ * unmap the address and return 1 or 0 depending if the mapping previously
+ * existed or not.
+ */
+int mmu_notifier_age_page(struct mm_struct *mm, unsigned long address)
+{
+ struct mmu_notifier *mn;
+ struct hlist_node *n;
+ int young = 0;
+
+ if (unlikely(!hlist_empty(&mm->mmu_notifier.head))) {
+ rcu_read_lock();
+ hlist_for_each_entry_rcu(mn, n,
+ &mm->mmu_notifier.head, hlist) {
+ if (mn->ops->age_page)
+ young |= mn->ops->age_page(mn, mm, address);
+ }
+ rcu_read_unlock();
+ }
+
+ return young;
+}
+
+static DEFINE_SPINLOCK(mmu_notifier_list_lock);
+
+void mmu_notifier_register(struct mmu_notifier *mn, struct mm_struct *mm)
+{
+ spin_lock(&mmu_notifier_list_lock);
+ hlist_add_head(&mn->hlist, &mm->mmu_notifier.head);
+ spin_unlock(&mmu_notifier_list_lock);
+}
+EXPORT_SYMBOL_GPL(mmu_notifier_register);
+
+void mmu_notifier_unregister(struct mmu_notifier *mn, struct mm_struct *mm)
+{
+ spin_lock(&mmu_notifier_list_lock);
+ hlist_del(&mn->hlist);
+ spin_unlock(&mmu_notifier_list_lock);
+}
+EXPORT_SYMBOL_GPL(mmu_notifier_unregister);
+
+HLIST_HEAD(mmu_rmap_notifier_list);
+
+void mmu_rmap_notifier_register(struct mmu_rmap_notifier *mrn)
+{
+ spin_lock(&mmu_notifier_list_lock);
+ hlist_add_head_rcu(&mrn->hlist, &mmu_rmap_notifier_list);
+ spin_unlock(&mmu_notifier_list_lock);
+}
+EXPORT_SYMBOL(mmu_rmap_notifier_register);
+
+void mmu_rmap_notifier_unregister(struct mmu_rmap_notifier *mrn)
+{
+ spin_lock(&mmu_notifier_list_lock);
+ hlist_del_rcu(&mrn->hlist);
+ spin_unlock(&mmu_notifier_list_lock);
+}
+EXPORT_SYMBOL(mmu_rmap_notifier_unregister);
+
Index: linux-2.6/kernel/fork.c
===================================================================
--- linux-2.6.orig/kernel/fork.c 2008-01-24 20:59:17.000000000 -0800
+++ linux-2.6/kernel/fork.c 2008-01-24 20:59:19.000000000 -0800
@@ -51,6 +51,7 @@
#include <linux/random.h>
#include <linux/tty.h>
#include <linux/proc_fs.h>
+#include <linux/mmu_notifier.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
@@ -359,6 +360,7 @@ static struct mm_struct * mm_init(struct
if (likely(!mm_alloc_pgd(mm))) {
mm->def_flags = 0;
+ mmu_notifier_head_init(&mm->mmu_notifier);
return mm;
}
free_mm(mm);
Index: linux-2.6/mm/mmap.c
===================================================================
--- linux-2.6.orig/mm/mmap.c 2008-01-24 20:59:17.000000000 -0800
+++ linux-2.6/mm/mmap.c 2008-01-24 20:59:19.000000000 -0800
@@ -26,6 +26,7 @@
#include <linux/mount.h>
#include <linux/mempolicy.h>
#include <linux/rmap.h>
+#include <linux/mmu_notifier.h>
#include <asm/uaccess.h>
#include <asm/cacheflush.h>
@@ -2043,6 +2044,7 @@ 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);
+ mmu_notifier_release(mm);
/*
* Walk the list again, actually closing and freeing it,
--
--
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