[PATCH 01 of 12] Core of mmu notifiers

From: Andrea Arcangeli
Date: Tue Apr 22 2008 - 10:12:15 EST

# HG changeset patch
# User Andrea Arcangeli <andrea@xxxxxxxxxxxx>
# Date 1208870142 -7200
# Node ID ea87c15371b1bd49380c40c3f15f1c7ca4438af5
# Parent fb3bc9942fb78629d096bd07564f435d51d86e5f
Core of mmu notifiers.

Signed-off-by: Andrea Arcangeli <andrea@xxxxxxxxxxxx>
Signed-off-by: Nick Piggin <npiggin@xxxxxxx>
Signed-off-by: Christoph Lameter <clameter@xxxxxxx>

diff --git a/include/linux/mm.h b/include/linux/mm.h
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1050,6 +1050,27 @@
unsigned long addr, unsigned long len,
unsigned long flags, struct page **pages);

+/*
+ * mm_lock will take mmap_sem writably (to prevent all modifications
+ * and scanning of vmas) and then also takes the mapping locks for
+ * each of the vma to lockout any scans of pagetables of this address
+ * space. This can be used to effectively holding off reclaim from the
+ * address space.
+ *
+ * mm_lock can fail if there is not enough memory to store a pointer
+ * array to all vmas.
+ *
+ * mm_lock and mm_unlock are expensive operations that may take a long time.
+ */
+struct mm_lock_data {
+ spinlock_t **i_mmap_locks;
+ spinlock_t **anon_vma_locks;
+ size_t nr_i_mmap_locks;
+ size_t nr_anon_vma_locks;
+};
+extern int mm_lock(struct mm_struct *mm, struct mm_lock_data *data);
+extern void mm_unlock(struct mm_struct *mm, struct mm_lock_data *data);
+
extern unsigned long get_unmapped_area(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);

extern unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -225,6 +225,9 @@
#ifdef CONFIG_CGROUP_MEM_RES_CTLR
struct mem_cgroup *mem_cgroup;
#endif
+#ifdef CONFIG_MMU_NOTIFIER
+ struct hlist_head mmu_notifier_list;
+#endif
};

#endif /* _LINUX_MM_TYPES_H */
diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
new file mode 100644
--- /dev/null
+++ b/include/linux/mmu_notifier.h
@@ -0,0 +1,229 @@
+#ifndef _LINUX_MMU_NOTIFIER_H
+#define _LINUX_MMU_NOTIFIER_H
+
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/mm_types.h>
+
+struct mmu_notifier;
+struct mmu_notifier_ops;
+
+#ifdef CONFIG_MMU_NOTIFIER
+
+struct mmu_notifier_ops {
+ /*
+ * Called after all other threads have terminated and the executing
+ * thread is the only remaining execution thread. There are no
+ * users of the mm_struct remaining.
+ */
+ void (*release)(struct mmu_notifier *mn,
+ struct mm_struct *mm);
+
+ /*
+ * clear_flush_young is called after the VM is
+ * test-and-clearing the young/accessed bitflag in the
+ * pte. This way the VM will provide proper aging to the
+ * accesses to the page through the secondary MMUs and not
+ * only to the ones through the Linux pte.
+ */
+ int (*clear_flush_young)(struct mmu_notifier *mn,
+ struct mm_struct *mm,
+ unsigned long address);
+
+ /*
+ * Before this is invoked any secondary MMU is still ok to
+ * read/write to the page previously pointed by the Linux pte
+ * because the old page hasn't been freed yet. If required
+ * set_page_dirty has to be called internally to this method.
+ */
+ void (*invalidate_page)(struct mmu_notifier *mn,
+ struct mm_struct *mm,
+ unsigned long address);
+
+ /*
+ * invalidate_range_start() and invalidate_range_end() must be
+ * paired and are called only when the mmap_sem is held and/or
+ * the semaphores protecting the reverse maps. Both functions
+ * may sleep. The subsystem must guarantee that no additional
+ * references to the pages in the range established between
+ * the call to invalidate_range_start() and the matching call
+ * to invalidate_range_end().
+ *
+ * Invalidation of multiple concurrent ranges may be permitted
+ * by the driver or the driver may exclude other invalidation
+ * from proceeding by blocking on new invalidate_range_start()
+ * callback that overlap invalidates that are already in
+ * progress. Either way the establishment of sptes to the
+ * range can only be allowed if all invalidate_range_stop()
+ * function have been called.
+ *
+ * invalidate_range_start() is called when all pages in the
+ * range are still mapped and have at least a refcount of one.
+ *
+ * invalidate_range_end() is called when all pages in the
+ * range have been unmapped and the pages have been freed by
+ * the VM.
+ *
+ * The VM will remove the page table entries and potentially
+ * the page between invalidate_range_start() and
+ * invalidate_range_end(). If the page must not be freed
+ * because of pending I/O or other circumstances then the
+ * invalidate_range_start() callback (or the initial mapping
+ * by the driver) must make sure that the refcount is kept
+ * elevated.
+ *
+ * If the driver increases the refcount when the pages are
+ * initially mapped into an address space then either
+ * invalidate_range_start() or invalidate_range_end() may
+ * decrease the refcount. If the refcount is decreased on
+ * invalidate_range_start() then the VM can free pages as page
+ * table entries are removed. If the refcount is only
+ * droppped on invalidate_range_end() then the driver itself
+ * will drop the last refcount but it must take care to flush
+ * any secondary tlb before doing the final free on the
+ * page. Pages will no longer be referenced by the linux
+ * address space but may still be referenced by sptes until
+ * the last refcount is dropped.
+ */
+ void (*invalidate_range_start)(struct mmu_notifier *mn,
+ struct mm_struct *mm,
+ unsigned long start, unsigned long end);
+ void (*invalidate_range_end)(struct mmu_notifier *mn,
+ struct mm_struct *mm,
+ unsigned long start, unsigned long end);
+};
+
+/*
+ * The notifier chains are protected by mmap_sem and/or the reverse map
+ * semaphores. Notifier chains are only changed when all reverse maps and
+ * the mmap_sem locks are taken.
+ *
+ * Therefore notifier chains can only be traversed when either
+ *
+ * 1. mmap_sem is held.
+ * 2. One of the reverse map locks is held (i_mmap_sem or anon_vma->sem).
+ * 3. No other concurrent thread can access the list (release)
+ */
+struct mmu_notifier {
+ struct hlist_node hlist;
+ const struct mmu_notifier_ops *ops;
+};
+
+static inline int mm_has_notifiers(struct mm_struct *mm)
+{
+ return unlikely(!hlist_empty(&mm->mmu_notifier_list));
+}
+
+extern int mmu_notifier_register(struct mmu_notifier *mn,
+ struct mm_struct *mm);
+extern int mmu_notifier_unregister(struct mmu_notifier *mn,
+ struct mm_struct *mm);
+extern void __mmu_notifier_release(struct mm_struct *mm);
+extern int __mmu_notifier_clear_flush_young(struct mm_struct *mm,
+ unsigned long address);
+extern void __mmu_notifier_invalidate_page(struct mm_struct *mm,
+ unsigned long address);
+extern void __mmu_notifier_invalidate_range_start(struct mm_struct *mm,
+ unsigned long start, unsigned long end);
+extern void __mmu_notifier_invalidate_range_end(struct mm_struct *mm,
+ unsigned long start, unsigned long end);
+
+
+static inline void mmu_notifier_release(struct mm_struct *mm)
+{
+ if (mm_has_notifiers(mm))
+ __mmu_notifier_release(mm);
+}
+
+static inline int mmu_notifier_clear_flush_young(struct mm_struct *mm,
+ unsigned long address)
+{
+ if (mm_has_notifiers(mm))
+ return __mmu_notifier_clear_flush_young(mm, address);
+ return 0;
+}
+
+static inline void mmu_notifier_invalidate_page(struct mm_struct *mm,
+ unsigned long address)
+{
+ if (mm_has_notifiers(mm))
+ __mmu_notifier_invalidate_page(mm, address);
+}
+
+static inline void mmu_notifier_invalidate_range_start(struct mm_struct *mm,
+ unsigned long start, unsigned long end)
+{
+ if (mm_has_notifiers(mm))
+ __mmu_notifier_invalidate_range_start(mm, start, end);
+}
+
+static inline void mmu_notifier_invalidate_range_end(struct mm_struct *mm,
+ unsigned long start, unsigned long end)
+{
+ if (mm_has_notifiers(mm))
+ __mmu_notifier_invalidate_range_end(mm, start, end);
+}
+
+static inline void mmu_notifier_mm_init(struct mm_struct *mm)
+{
+ INIT_HLIST_HEAD(&mm->mmu_notifier_list);
+}
+
+#define ptep_clear_flush_notify(__vma, __address, __ptep) \
+({ \
+ pte_t __pte; \
+ struct vm_area_struct *___vma = __vma; \
+ unsigned long ___address = __address; \
+ __pte = ptep_clear_flush(___vma, ___address, __ptep); \
+ mmu_notifier_invalidate_page(___vma->vm_mm, ___address); \
+ __pte; \
+})
+
+#define ptep_clear_flush_young_notify(__vma, __address, __ptep) \
+({ \
+ int __young; \
+ struct vm_area_struct *___vma = __vma; \
+ unsigned long ___address = __address; \
+ __young = ptep_clear_flush_young(___vma, ___address, __ptep); \
+ __young |= mmu_notifier_clear_flush_young(___vma->vm_mm, \
+ ___address); \
+ __young; \
+})
+
+#else /* CONFIG_MMU_NOTIFIER */
+
+static inline void mmu_notifier_release(struct mm_struct *mm)
+{
+}
+
+static inline int mmu_notifier_clear_flush_young(struct mm_struct *mm,
+ unsigned long address)
+{
+ return 0;
+}
+
+static inline void mmu_notifier_invalidate_page(struct mm_struct *mm,
+ unsigned long address)
+{
+}
+
+static inline void mmu_notifier_invalidate_range_start(struct mm_struct *mm,
+ unsigned long start, unsigned long end)
+{
+}
+
+static inline void mmu_notifier_invalidate_range_end(struct mm_struct *mm,
+ unsigned long start, unsigned long end)
+{
+}
+
+static inline void mmu_notifier_mm_init(struct mm_struct *mm)
+{
+}
+
+#define ptep_clear_flush_young_notify ptep_clear_flush_young
+#define ptep_clear_flush_notify ptep_clear_flush
+
+#endif /* CONFIG_MMU_NOTIFIER */
+
+#endif /* _LINUX_MMU_NOTIFIER_H */
diff --git a/kernel/fork.c b/kernel/fork.c
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -53,6 +53,7 @@
#include <linux/tty.h>
#include <linux/proc_fs.h>
#include <linux/blkdev.h>
+#include <linux/mmu_notifier.h>

#include <asm/pgtable.h>
#include <asm/pgalloc.h>
@@ -362,6 +363,7 @@

if (likely(!mm_alloc_pgd(mm))) {
mm->def_flags = 0;
+ mmu_notifier_mm_init(mm);
return mm;
}

diff --git a/mm/Kconfig b/mm/Kconfig
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -193,3 +193,7 @@
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"
diff --git a/mm/Makefile b/mm/Makefile
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -33,4 +33,5 @@
obj-$(CONFIG_SMP) += allocpercpu.o
obj-$(CONFIG_QUICKLIST) += quicklist.o
obj-$(CONFIG_CGROUP_MEM_RES_CTLR) += memcontrol.o
+obj-$(CONFIG_MMU_NOTIFIER) += mmu_notifier.o

diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c
--- a/mm/filemap_xip.c
+++ b/mm/filemap_xip.c
@@ -194,7 +194,7 @@
if (pte) {
/* Nuke the page table entry. */
flush_cache_page(vma, address, pte_pfn(*pte));
- pteval = ptep_clear_flush(vma, address, pte);
+ pteval = ptep_clear_flush_notify(vma, address, pte);
page_remove_rmap(page, vma);
dec_mm_counter(mm, file_rss);
BUG_ON(pte_dirty(pteval));
diff --git a/mm/fremap.c b/mm/fremap.c
--- a/mm/fremap.c
+++ b/mm/fremap.c
@@ -15,6 +15,7 @@
#include <linux/rmap.h>
#include <linux/module.h>
#include <linux/syscalls.h>
+#include <linux/mmu_notifier.h>

#include <asm/mmu_context.h>
#include <asm/cacheflush.h>
@@ -214,7 +215,9 @@
spin_unlock(&mapping->i_mmap_lock);
}

+ mmu_notifier_invalidate_range_start(mm, start, start + size);
err = populate_range(mm, vma, start, size, pgoff);
+ mmu_notifier_invalidate_range_end(mm, start, start + size);
if (!err && !(flags & MAP_NONBLOCK)) {
if (unlikely(has_write_lock)) {
downgrade_write(&mm->mmap_sem);
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -14,6 +14,7 @@
#include <linux/mempolicy.h>
#include <linux/cpuset.h>
#include <linux/mutex.h>
+#include <linux/mmu_notifier.h>

#include <asm/page.h>
#include <asm/pgtable.h>
@@ -799,6 +800,7 @@
BUG_ON(start & ~HPAGE_MASK);
BUG_ON(end & ~HPAGE_MASK);

+ mmu_notifier_invalidate_range_start(mm, start, end);
spin_lock(&mm->page_table_lock);
for (address = start; address < end; address += HPAGE_SIZE) {
ptep = huge_pte_offset(mm, address);
@@ -819,6 +821,7 @@
}
spin_unlock(&mm->page_table_lock);
flush_tlb_range(vma, start, end);
+ mmu_notifier_invalidate_range_end(mm, start, end);
list_for_each_entry_safe(page, tmp, &page_list, lru) {
list_del(&page->lru);
put_page(page);
diff --git a/mm/memory.c b/mm/memory.c
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -51,6 +51,7 @@
#include <linux/init.h>
#include <linux/writeback.h>
#include <linux/memcontrol.h>
+#include <linux/mmu_notifier.h>

#include <asm/pgalloc.h>
#include <asm/uaccess.h>
@@ -611,6 +612,9 @@
if (is_vm_hugetlb_page(vma))
return copy_hugetlb_page_range(dst_mm, src_mm, vma);

+ if (is_cow_mapping(vma->vm_flags))
+ mmu_notifier_invalidate_range_start(src_mm, addr, end);
+
dst_pgd = pgd_offset(dst_mm, addr);
src_pgd = pgd_offset(src_mm, addr);
do {
@@ -621,6 +625,11 @@
vma, addr, next))
return -ENOMEM;
} while (dst_pgd++, src_pgd++, addr = next, addr != end);
+
+ if (is_cow_mapping(vma->vm_flags))
+ mmu_notifier_invalidate_range_end(src_mm,
+ vma->vm_start, end);
+
return 0;
}

@@ -825,7 +834,9 @@
unsigned long start = start_addr;
spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
int fullmm = (*tlbp)->fullmm;
+ struct mm_struct *mm = vma->vm_mm;

+ mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
unsigned long end;

@@ -876,6 +887,7 @@
}
}
out:
+ mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
return start; /* which is now the end (or restart) address */
}

@@ -1463,10 +1475,11 @@
{
pgd_t *pgd;
unsigned long next;
- unsigned long end = addr + size;
+ unsigned long start = addr, end = addr + size;
int err;

BUG_ON(addr >= end);
+ mmu_notifier_invalidate_range_start(mm, start, end);
pgd = pgd_offset(mm, addr);
do {
next = pgd_addr_end(addr, end);
@@ -1474,6 +1487,7 @@
if (err)
break;
} while (pgd++, addr = next, addr != end);
+ mmu_notifier_invalidate_range_end(mm, start, end);
return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);
@@ -1675,7 +1689,7 @@
* seen in the presence of one thread doing SMC and another
* thread doing COW.
*/
- ptep_clear_flush(vma, address, page_table);
+ ptep_clear_flush_notify(vma, address, page_table);
set_pte_at(mm, address, page_table, entry);
update_mmu_cache(vma, address, entry);
lru_cache_add_active(new_page);
diff --git a/mm/mmap.c b/mm/mmap.c
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -26,6 +26,9 @@
#include <linux/mount.h>
#include <linux/mempolicy.h>
#include <linux/rmap.h>
+#include <linux/vmalloc.h>
+#include <linux/sort.h>
+#include <linux/mmu_notifier.h>

#include <asm/uaccess.h>
#include <asm/cacheflush.h>
@@ -2038,6 +2041,7 @@

/* mm's last user has gone, and its about to be pulled down */
arch_exit_mmap(mm);
+ mmu_notifier_release(mm);

lru_add_drain();
flush_cache_mm(mm);
@@ -2242,3 +2246,143 @@

return 0;
}
+
+static int mm_lock_cmp(const void *a, const void *b)
+{
+ cond_resched();
+ if ((unsigned long)*(spinlock_t **)a <
+ (unsigned long)*(spinlock_t **)b)
+ return -1;
+ else if (a == b)
+ return 0;
+ else
+ return 1;
+}
+
+static unsigned long mm_lock_sort(struct mm_struct *mm, spinlock_t **locks,
+ int anon)
+{
+ struct vm_area_struct *vma;
+ size_t i = 0;
+
+ for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ if (anon) {
+ if (vma->anon_vma)
+ locks[i++] = &vma->anon_vma->lock;
+ } else {
+ if (vma->vm_file && vma->vm_file->f_mapping)
+ locks[i++] = &vma->vm_file->f_mapping->i_mmap_lock;
+ }
+ }
+
+ if (!i)
+ goto out;
+
+ sort(locks, i, sizeof(spinlock_t *), mm_lock_cmp, NULL);
+
+out:
+ return i;
+}
+
+static inline unsigned long mm_lock_sort_anon_vma(struct mm_struct *mm,
+ spinlock_t **locks)
+{
+ return mm_lock_sort(mm, locks, 1);
+}
+
+static inline unsigned long mm_lock_sort_i_mmap(struct mm_struct *mm,
+ spinlock_t **locks)
+{
+ return mm_lock_sort(mm, locks, 0);
+}
+
+static void mm_lock_unlock(spinlock_t **locks, size_t nr, int lock)
+{
+ spinlock_t *last = NULL;
+ size_t i;
+
+ for (i = 0; i < nr; i++)
+ /* Multiple vmas may use the same lock. */
+ if (locks[i] != last) {
+ BUG_ON((unsigned long) last > (unsigned long) locks[i]);
+ last = locks[i];
+ if (lock)
+ spin_lock(last);
+ else
+ spin_unlock(last);
+ }
+}
+
+static inline void __mm_lock(spinlock_t **locks, size_t nr)
+{
+ mm_lock_unlock(locks, nr, 1);
+}
+
+static inline void __mm_unlock(spinlock_t **locks, size_t nr)
+{
+ mm_lock_unlock(locks, nr, 0);
+}
+
+/*
+ * This operation locks against the VM for all pte/vma/mm related
+ * operations that could ever happen on a certain mm. This includes
+ * vmtruncate, try_to_unmap, and all page faults. The holder
+ * must not hold any mm related lock. A single task can't take more
+ * than one mm lock in a row or it would deadlock.
+ */
+int mm_lock(struct mm_struct *mm, struct mm_lock_data *data)
+{
+ spinlock_t **anon_vma_locks, **i_mmap_locks;
+
+ down_write(&mm->mmap_sem);
+ if (mm->map_count) {
+ anon_vma_locks = vmalloc(sizeof(spinlock_t *) * mm->map_count);
+ if (unlikely(!anon_vma_locks)) {
+ up_write(&mm->mmap_sem);
+ return -ENOMEM;
+ }
+
+ i_mmap_locks = vmalloc(sizeof(spinlock_t *) * mm->map_count);
+ if (unlikely(!i_mmap_locks)) {
+ up_write(&mm->mmap_sem);
+ vfree(anon_vma_locks);
+ return -ENOMEM;
+ }
+
+ data->nr_anon_vma_locks = mm_lock_sort_anon_vma(mm, anon_vma_locks);
+ data->nr_i_mmap_locks = mm_lock_sort_i_mmap(mm, i_mmap_locks);
+
+ if (data->nr_anon_vma_locks) {
+ __mm_lock(anon_vma_locks, data->nr_anon_vma_locks);
+ data->anon_vma_locks = anon_vma_locks;
+ } else
+ vfree(anon_vma_locks);
+
+ if (data->nr_i_mmap_locks) {
+ __mm_lock(i_mmap_locks, data->nr_i_mmap_locks);
+ data->i_mmap_locks = i_mmap_locks;
+ } else
+ vfree(i_mmap_locks);
+ }
+ return 0;
+}
+
+static void mm_unlock_vfree(spinlock_t **locks, size_t nr)
+{
+ __mm_unlock(locks, nr);
+ vfree(locks);
+}
+
+/* avoid memory allocations for mm_unlock to prevent deadlock */
+void mm_unlock(struct mm_struct *mm, struct mm_lock_data *data)
+{
+ if (mm->map_count) {
+ if (data->nr_anon_vma_locks)
+ mm_unlock_vfree(data->anon_vma_locks,
+ data->nr_anon_vma_locks);
+ if (data->i_mmap_locks)
+ mm_unlock_vfree(data->i_mmap_locks,
+ data->nr_i_mmap_locks);
+ }
+ up_write(&mm->mmap_sem);
+}
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
new file mode 100644
--- /dev/null
+++ b/mm/mmu_notifier.c
@@ -0,0 +1,130 @@
+/*
+ * 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>
+#include <linux/mm.h>
+#include <linux/err.h>
+
+/*
+ * No synchronization. This function can only be called when only a single
+ * process remains that performs teardown.
+ */
+void __mmu_notifier_release(struct mm_struct *mm)
+{
+ struct mmu_notifier *mn;
+
+ while (unlikely(!hlist_empty(&mm->mmu_notifier_list))) {
+ mn = hlist_entry(mm->mmu_notifier_list.first,
+ struct mmu_notifier,
+ hlist);
+ hlist_del(&mn->hlist);
+ if (mn->ops->release)
+ mn->ops->release(mn, mm);
+ }
+}
+
+/*
+ * If no young bitflag is supported by the hardware, ->clear_flush_young can
+ * unmap the address and return 1 or 0 depending if the mapping previously
+ * existed or not.
+ */
+int __mmu_notifier_clear_flush_young(struct mm_struct *mm,
+ unsigned long address)
+{
+ struct mmu_notifier *mn;
+ struct hlist_node *n;
+ int young = 0;
+
+ hlist_for_each_entry(mn, n, &mm->mmu_notifier_list, hlist) {
+ if (mn->ops->clear_flush_young)
+ young |= mn->ops->clear_flush_young(mn, mm, address);
+ }
+
+ return young;
+}
+
+void __mmu_notifier_invalidate_page(struct mm_struct *mm,
+ unsigned long address)
+{
+ struct mmu_notifier *mn;
+ struct hlist_node *n;
+
+ hlist_for_each_entry(mn, n, &mm->mmu_notifier_list, hlist) {
+ if (mn->ops->invalidate_page)
+ mn->ops->invalidate_page(mn, mm, address);
+ }
+}
+
+void __mmu_notifier_invalidate_range_start(struct mm_struct *mm,
+ unsigned long start, unsigned long end)
+{
+ struct mmu_notifier *mn;
+ struct hlist_node *n;
+
+ hlist_for_each_entry(mn, n, &mm->mmu_notifier_list, hlist) {
+ if (mn->ops->invalidate_range_start)
+ mn->ops->invalidate_range_start(mn, mm, start, end);
+ }
+}
+
+void __mmu_notifier_invalidate_range_end(struct mm_struct *mm,
+ unsigned long start, unsigned long end)
+{
+ struct mmu_notifier *mn;
+ struct hlist_node *n;
+
+ hlist_for_each_entry(mn, n, &mm->mmu_notifier_list, hlist) {
+ if (mn->ops->invalidate_range_end)
+ mn->ops->invalidate_range_end(mn, mm, start, end);
+ }
+}
+
+/*
+ * Must not hold mmap_sem nor any other VM related lock when calling
+ * this registration function.
+ */
+int mmu_notifier_register(struct mmu_notifier *mn, struct mm_struct *mm)
+{
+ struct mm_lock_data data;
+ int ret;
+
+ ret = mm_lock(mm, &data);
+ if (unlikely(ret))
+ goto out;
+ hlist_add_head(&mn->hlist, &mm->mmu_notifier_list);
+ mm_unlock(mm, &data);
+out:
+ return ret;
+}
+EXPORT_SYMBOL_GPL(mmu_notifier_register);
+
+/*
+ * mm_users can't go down to zero while mmu_notifier_unregister()
+ * runs or it can race with ->release. So a mm_users pin must
+ * be taken by the caller (if mm can be different from current->mm).
+ */
+int mmu_notifier_unregister(struct mmu_notifier *mn, struct mm_struct *mm)
+{
+ struct mm_lock_data data;
+ int ret;
+
+ BUG_ON(!atomic_read(&mm->mm_users));
+
+ ret = mm_lock(mm, &data);
+ if (unlikely(ret))
+ goto out;
+ hlist_del(&mn->hlist);
+ mm_unlock(mm, &data);
+out:
+ return ret;
+}
+EXPORT_SYMBOL_GPL(mmu_notifier_unregister);
diff --git a/mm/mprotect.c b/mm/mprotect.c
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -21,6 +21,7 @@
#include <linux/syscalls.h>
#include <linux/swap.h>
#include <linux/swapops.h>
+#include <linux/mmu_notifier.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/cacheflush.h>
@@ -198,10 +199,12 @@
dirty_accountable = 1;
}

+ mmu_notifier_invalidate_range_start(mm, start, end);
if (is_vm_hugetlb_page(vma))
hugetlb_change_protection(vma, start, end, vma->vm_page_prot);
else
change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable);
+ mmu_notifier_invalidate_range_end(mm, start, end);
vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
vm_stat_account(mm, newflags, vma->vm_file, nrpages);
return 0;
diff --git a/mm/mremap.c b/mm/mremap.c
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -18,6 +18,7 @@
#include <linux/highmem.h>
#include <linux/security.h>
#include <linux/syscalls.h>
+#include <linux/mmu_notifier.h>

#include <asm/uaccess.h>
#include <asm/cacheflush.h>
@@ -74,7 +75,11 @@
struct mm_struct *mm = vma->vm_mm;
pte_t *old_pte, *new_pte, pte;
spinlock_t *old_ptl, *new_ptl;
+ unsigned long old_start;

+ old_start = old_addr;
+ mmu_notifier_invalidate_range_start(vma->vm_mm,
+ old_start, old_end);
if (vma->vm_file) {
/*
* Subtle point from Rajesh Venkatasubramanian: before
@@ -116,6 +121,7 @@
pte_unmap_unlock(old_pte - 1, old_ptl);
if (mapping)
spin_unlock(&mapping->i_mmap_lock);
+ mmu_notifier_invalidate_range_end(vma->vm_mm, old_start, old_end);
}

#define LATENCY_LIMIT (64 * PAGE_SIZE)
diff --git a/mm/rmap.c b/mm/rmap.c
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -49,6 +49,7 @@
#include <linux/module.h>
#include <linux/kallsyms.h>
#include <linux/memcontrol.h>
+#include <linux/mmu_notifier.h>

#include <asm/tlbflush.h>

@@ -287,7 +288,7 @@
if (vma->vm_flags & VM_LOCKED) {
referenced++;
*mapcount = 1; /* break early from loop */
- } else if (ptep_clear_flush_young(vma, address, pte))
+ } else if (ptep_clear_flush_young_notify(vma, address, pte))
referenced++;

/* Pretend the page is referenced if the task has the
@@ -456,7 +457,7 @@
pte_t entry;

flush_cache_page(vma, address, pte_pfn(*pte));
- entry = ptep_clear_flush(vma, address, pte);
+ entry = ptep_clear_flush_notify(vma, address, pte);
entry = pte_wrprotect(entry);
entry = pte_mkclean(entry);
set_pte_at(mm, address, pte, entry);
@@ -717,14 +718,14 @@
* skipped over this mm) then we should reactivate it.
*/
if (!migration && ((vma->vm_flags & VM_LOCKED) ||
- (ptep_clear_flush_young(vma, address, pte)))) {
+ (ptep_clear_flush_young_notify(vma, address, pte)))) {
ret = SWAP_FAIL;
goto out_unmap;
}

/* Nuke the page table entry. */
flush_cache_page(vma, address, page_to_pfn(page));
- pteval = ptep_clear_flush(vma, address, pte);
+ pteval = ptep_clear_flush_notify(vma, address, pte);

/* Move the dirty bit to the physical page now the pte is gone. */
if (pte_dirty(pteval))
@@ -849,12 +850,12 @@
page = vm_normal_page(vma, address, *pte);
BUG_ON(!page || PageAnon(page));

- if (ptep_clear_flush_young(vma, address, pte))
+ if (ptep_clear_flush_young_notify(vma, address, pte))
continue;

/* Nuke the page table entry. */
flush_cache_page(vma, address, pte_pfn(*pte));
- pteval = ptep_clear_flush(vma, address, pte);
+ pteval = ptep_clear_flush_notify(vma, address, pte);

/* If nonlinear, store the file page offset in the pte. */
if (page->index != linear_page_index(vma, address))
--
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