14 files changed, 511 insertions, 18 deletions

diff --git a/mm/Kconfig b/mm/Kconfig
index efee5d379df4..446c6588c753 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -208,3 +208,6 @@ config NR_QUICK
 config VIRT_TO_BUS
         def_bool y
         depends on !ARCH_NO_VIRT_TO_BUS
+
+config MMU_NOTIFIER
+        bool
diff --git a/mm/Makefile b/mm/Makefile
index 06ca2381fef1..da4ccf015aea 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -25,6 +25,7 @@ obj-$(CONFIG_SHMEM) += shmem.o
 obj-$(CONFIG_TMPFS_POSIX_ACL) += shmem_acl.o
 obj-$(CONFIG_TINY_SHMEM) += tiny-shmem.o
 obj-$(CONFIG_SLOB) += slob.o
+obj-$(CONFIG_MMU_NOTIFIER) += mmu_notifier.o
 obj-$(CONFIG_SLAB) += slab.o
 obj-$(CONFIG_SLUB) += slub.o
 obj-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o
diff --git a/mm/filemap.c b/mm/filemap.c
index 5de7633e1dbe..42bbc6909ba4 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1023,8 +1023,17 @@ find_page:
                                         ra, filp, page,
                                         index, last_index - index);
                 }
-                if (!PageUptodate(page))
-                        goto page_not_up_to_date;
+                if (!PageUptodate(page)) {
+                        if (inode->i_blkbits == PAGE_CACHE_SHIFT ||
+                                        !mapping->a_ops->is_partially_uptodate)
+                                goto page_not_up_to_date;
+                        if (TestSetPageLocked(page))
+                                goto page_not_up_to_date;
+                        if (!mapping->a_ops->is_partially_uptodate(page,
+                                                                desc, offset))
+                                goto page_not_up_to_date_locked;
+                        unlock_page(page);
+                }
 page_ok:
                 /*
                  * i_size must be checked after we know the page is Uptodate.
@@ -1094,6 +1103,7 @@ page_not_up_to_date:
                 if (lock_page_killable(page))
                         goto readpage_eio;
 
+page_not_up_to_date_locked:
                 /* Did it get truncated before we got the lock? */
                 if (!page->mapping) {
                         unlock_page(page);
diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c
index 98a3f31ccd6a..380ab402d711 100644
--- a/mm/filemap_xip.c
+++ b/mm/filemap_xip.c
@@ -13,6 +13,7 @@
 #include <linux/module.h>
 #include <linux/uio.h>
 #include <linux/rmap.h>
+#include <linux/mmu_notifier.h>
 #include <linux/sched.h>
 #include <asm/tlbflush.h>
 #include <asm/io.h>
@@ -188,7 +189,7 @@ __xip_unmap (struct address_space * mapping,
                 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
index 07a9c82ce1a3..7881638e4a12 100644
--- 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 @@ asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size,
                 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
index 3be79dc18c5c..254ce2b90158 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -9,6 +9,7 @@
 #include <linux/mm.h>
 #include <linux/sysctl.h>
 #include <linux/highmem.h>
+#include <linux/mmu_notifier.h>
 #include <linux/nodemask.h>
 #include <linux/pagemap.h>
 #include <linux/mempolicy.h>
@@ -19,6 +20,7 @@
 
 #include <asm/page.h>
 #include <asm/pgtable.h>
+#include <asm/io.h>
 
 #include <linux/hugetlb.h>
 #include "internal.h"
@@ -1672,6 +1674,7 @@ void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
         BUG_ON(start & ~huge_page_mask(h));
         BUG_ON(end & ~huge_page_mask(h));
 
+        mmu_notifier_invalidate_range_start(mm, start, end);
         spin_lock(&mm->page_table_lock);
         for (address = start; address < end; address += sz) {
                 ptep = huge_pte_offset(mm, address);
@@ -1713,6 +1716,7 @@ void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
         }
         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
index a8ca04faaea6..67f0ab9077d9 100644
--- 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>
@@ -652,6 +653,7 @@ int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
         unsigned long next;
         unsigned long addr = vma->vm_start;
         unsigned long end = vma->vm_end;
+        int ret;
 
         /*
          * Don't copy ptes where a page fault will fill them correctly.
@@ -667,17 +669,33 @@ int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
         if (is_vm_hugetlb_page(vma))
                 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
 
+        /*
+         * We need to invalidate the secondary MMU mappings only when
+         * there could be a permission downgrade on the ptes of the
+         * parent mm. And a permission downgrade will only happen if
+         * is_cow_mapping() returns true.
+         */
+        if (is_cow_mapping(vma->vm_flags))
+                mmu_notifier_invalidate_range_start(src_mm, addr, end);
+
+        ret = 0;
         dst_pgd = pgd_offset(dst_mm, addr);
         src_pgd = pgd_offset(src_mm, addr);
         do {
                 next = pgd_addr_end(addr, end);
                 if (pgd_none_or_clear_bad(src_pgd))
                         continue;
-                if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
-                                                vma, addr, next))
-                        return -ENOMEM;
+                if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
+                                            vma, addr, next))) {
+                        ret = -ENOMEM;
+                        break;
+                }
         } while (dst_pgd++, src_pgd++, addr = next, addr != end);
-        return 0;
+
+        if (is_cow_mapping(vma->vm_flags))
+                mmu_notifier_invalidate_range_end(src_mm,
+                                                  vma->vm_start, end);
+        return ret;
 }
 
 static unsigned long zap_pte_range(struct mmu_gather *tlb,
@@ -881,7 +899,9 @@ unsigned long unmap_vmas(struct mmu_gather **tlbp,
         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;
 
@@ -946,6 +966,7 @@ unsigned long unmap_vmas(struct mmu_gather **tlbp,
                 }
         }
 out:
+        mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
         return start;   /* which is now the end (or restart) address */
 }
 
@@ -1616,10 +1637,11 @@ int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
 {
         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);
@@ -1627,6 +1649,7 @@ int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
                 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);
@@ -1839,7 +1862,7 @@ gotten:
                  * 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
index 5e0cc99e9cd5..245c3d69067b 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -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>
@@ -2061,6 +2062,7 @@ void exit_mmap(struct mm_struct *mm)
 
         /* 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);
@@ -2268,3 +2270,161 @@ int install_special_mapping(struct mm_struct *mm,
 
         return 0;
 }
+
+static DEFINE_MUTEX(mm_all_locks_mutex);
+
+static void vm_lock_anon_vma(struct anon_vma *anon_vma)
+{
+        if (!test_bit(0, (unsigned long *) &anon_vma->head.next)) {
+                /*
+                 * The LSB of head.next can't change from under us
+                 * because we hold the mm_all_locks_mutex.
+                 */
+                spin_lock(&anon_vma->lock);
+                /*
+                 * We can safely modify head.next after taking the
+                 * anon_vma->lock. If some other vma in this mm shares
+                 * the same anon_vma we won't take it again.
+                 *
+                 * No need of atomic instructions here, head.next
+                 * can't change from under us thanks to the
+                 * anon_vma->lock.
+                 */
+                if (__test_and_set_bit(0, (unsigned long *)
+                                       &anon_vma->head.next))
+                        BUG();
+        }
+}
+
+static void vm_lock_mapping(struct address_space *mapping)
+{
+        if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
+                /*
+                 * AS_MM_ALL_LOCKS can't change from under us because
+                 * we hold the mm_all_locks_mutex.
+                 *
+                 * Operations on ->flags have to be atomic because
+                 * even if AS_MM_ALL_LOCKS is stable thanks to the
+                 * mm_all_locks_mutex, there may be other cpus
+                 * changing other bitflags in parallel to us.
+                 */
+                if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
+                        BUG();
+                spin_lock(&mapping->i_mmap_lock);
+        }
+}
+
+/*
+ * 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 caller must take the mmap_sem in write mode before calling
+ * mm_take_all_locks(). The caller isn't allowed to release the
+ * mmap_sem until mm_drop_all_locks() returns.
+ *
+ * mmap_sem in write mode is required in order to block all operations
+ * that could modify pagetables and free pages without need of
+ * altering the vma layout (for example populate_range() with
+ * nonlinear vmas). It's also needed in write mode to avoid new
+ * anon_vmas to be associated with existing vmas.
+ *
+ * A single task can't take more than one mm_take_all_locks() in a row
+ * or it would deadlock.
+ *
+ * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in
+ * mapping->flags avoid to take the same lock twice, if more than one
+ * vma in this mm is backed by the same anon_vma or address_space.
+ *
+ * We can take all the locks in random order because the VM code
+ * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never
+ * takes more than one of them in a row. Secondly we're protected
+ * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
+ *
+ * mm_take_all_locks() and mm_drop_all_locks are expensive operations
+ * that may have to take thousand of locks.
+ *
+ * mm_take_all_locks() can fail if it's interrupted by signals.
+ */
+int mm_take_all_locks(struct mm_struct *mm)
+{
+        struct vm_area_struct *vma;
+        int ret = -EINTR;
+
+        BUG_ON(down_read_trylock(&mm->mmap_sem));
+
+        mutex_lock(&mm_all_locks_mutex);
+
+        for (vma = mm->mmap; vma; vma = vma->vm_next) {
+                if (signal_pending(current))
+                        goto out_unlock;
+                if (vma->anon_vma)
+                        vm_lock_anon_vma(vma->anon_vma);
+                if (vma->vm_file && vma->vm_file->f_mapping)
+                        vm_lock_mapping(vma->vm_file->f_mapping);
+        }
+        ret = 0;
+
+out_unlock:
+        if (ret)
+                mm_drop_all_locks(mm);
+
+        return ret;
+}
+
+static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
+{
+        if (test_bit(0, (unsigned long *) &anon_vma->head.next)) {
+                /*
+                 * The LSB of head.next can't change to 0 from under
+                 * us because we hold the mm_all_locks_mutex.
+                 *
+                 * We must however clear the bitflag before unlocking
+                 * the vma so the users using the anon_vma->head will
+                 * never see our bitflag.
+                 *
+                 * No need of atomic instructions here, head.next
+                 * can't change from under us until we release the
+                 * anon_vma->lock.
+                 */
+                if (!__test_and_clear_bit(0, (unsigned long *)
+                                          &anon_vma->head.next))
+                        BUG();
+                spin_unlock(&anon_vma->lock);
+        }
+}
+
+static void vm_unlock_mapping(struct address_space *mapping)
+{
+        if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
+                /*
+                 * AS_MM_ALL_LOCKS can't change to 0 from under us
+                 * because we hold the mm_all_locks_mutex.
+                 */
+                spin_unlock(&mapping->i_mmap_lock);
+                if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
+                                        &mapping->flags))
+                        BUG();
+        }
+}
+
+/*
+ * The mmap_sem cannot be released by the caller until
+ * mm_drop_all_locks() returns.
+ */
+void mm_drop_all_locks(struct mm_struct *mm)
+{
+        struct vm_area_struct *vma;
+
+        BUG_ON(down_read_trylock(&mm->mmap_sem));
+        BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
+
+        for (vma = mm->mmap; vma; vma = vma->vm_next) {
+                if (vma->anon_vma)
+                        vm_unlock_anon_vma(vma->anon_vma);
+                if (vma->vm_file && vma->vm_file->f_mapping)
+                        vm_unlock_mapping(vma->vm_file->f_mapping);
+        }
+
+        mutex_unlock(&mm_all_locks_mutex);
+}
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
new file mode 100644
index 000000000000..5f4ef0250bee
--- /dev/null
+++ b/mm/mmu_notifier.c
@@ -0,0 +1,277 @@
+/*
+ *  linux/mm/mmu_notifier.c
+ *
+ *  Copyright (C) 2008  Qumranet, Inc.
+ *  Copyright (C) 2008  SGI
+ *             Christoph Lameter <clameter@sgi.com>
+ *
+ *  This work is licensed under the terms of the GNU GPL, version 2. See
+ *  the COPYING file in the top-level directory.
+ */
+
+#include <linux/rculist.h>
+#include <linux/mmu_notifier.h>
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/err.h>
+#include <linux/rcupdate.h>
+#include <linux/sched.h>
+
+/*
+ * This function can't run concurrently against mmu_notifier_register
+ * because mm->mm_users > 0 during mmu_notifier_register and exit_mmap
+ * runs with mm_users == 0. Other tasks may still invoke mmu notifiers
+ * in parallel despite there being no task using this mm any more,
+ * through the vmas outside of the exit_mmap context, such as with
+ * vmtruncate. This serializes against mmu_notifier_unregister with
+ * the mmu_notifier_mm->lock in addition to RCU and it serializes
+ * against the other mmu notifiers with RCU. struct mmu_notifier_mm
+ * can't go away from under us as exit_mmap holds an mm_count pin
+ * itself.
+ */
+void __mmu_notifier_release(struct mm_struct *mm)
+{
+        struct mmu_notifier *mn;
+
+        spin_lock(&mm->mmu_notifier_mm->lock);
+        while (unlikely(!hlist_empty(&mm->mmu_notifier_mm->list))) {
+                mn = hlist_entry(mm->mmu_notifier_mm->list.first,
+                                 struct mmu_notifier,
+                                 hlist);
+                /*
+                 * We arrived before mmu_notifier_unregister so
+                 * mmu_notifier_unregister will do nothing other than
+                 * to wait ->release to finish and
+                 * mmu_notifier_unregister to return.
+                 */
+                hlist_del_init_rcu(&mn->hlist);
+                /*
+                 * RCU here will block mmu_notifier_unregister until
+                 * ->release returns.
+                 */
+                rcu_read_lock();
+                spin_unlock(&mm->mmu_notifier_mm->lock);
+                /*
+                 * if ->release runs before mmu_notifier_unregister it
+                 * must be handled as it's the only way for the driver
+                 * to flush all existing sptes and stop the driver
+                 * from establishing any more sptes before all the
+                 * pages in the mm are freed.
+                 */
+                if (mn->ops->release)
+                        mn->ops->release(mn, mm);
+                rcu_read_unlock();
+                spin_lock(&mm->mmu_notifier_mm->lock);
+        }
+        spin_unlock(&mm->mmu_notifier_mm->lock);
+
+        /*
+         * synchronize_rcu here prevents mmu_notifier_release to
+         * return to exit_mmap (which would proceed freeing all pages
+         * in the mm) until the ->release method returns, if it was
+         * invoked by mmu_notifier_unregister.
+         *
+         * The mmu_notifier_mm can't go away from under us because one
+         * mm_count is hold by exit_mmap.
+         */
+        synchronize_rcu();
+}
+
+/*
+ * 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;
+
+        rcu_read_lock();
+        hlist_for_each_entry_rcu(mn, n, &mm->mmu_notifier_mm->list, hlist) {
+                if (mn->ops->clear_flush_young)
+                        young |= mn->ops->clear_flush_young(mn, mm, address);
+        }
+        rcu_read_unlock();
+
+        return young;
+}
+
+void __mmu_notifier_invalidate_page(struct mm_struct *mm,
+                                          unsigned long address)
+{
+        struct mmu_notifier *mn;
+        struct hlist_node *n;
+
+        rcu_read_lock();
+        hlist_for_each_entry_rcu(mn, n, &mm->mmu_notifier_mm->list, hlist) {
+                if (mn->ops->invalidate_page)
+                        mn->ops->invalidate_page(mn, mm, address);
+        }
+        rcu_read_unlock();
+}
+
+void __mmu_notifier_invalidate_range_start(struct mm_struct *mm,
+                                  unsigned long start, unsigned long end)
+{
+        struct mmu_notifier *mn;
+        struct hlist_node *n;
+
+        rcu_read_lock();
+        hlist_for_each_entry_rcu(mn, n, &mm->mmu_notifier_mm->list, hlist) {
+                if (mn->ops->invalidate_range_start)
+                        mn->ops->invalidate_range_start(mn, mm, start, end);
+        }
+        rcu_read_unlock();
+}
+
+void __mmu_notifier_invalidate_range_end(struct mm_struct *mm,
+                                  unsigned long start, unsigned long end)
+{
+        struct mmu_notifier *mn;
+        struct hlist_node *n;
+
+        rcu_read_lock();
+        hlist_for_each_entry_rcu(mn, n, &mm->mmu_notifier_mm->list, hlist) {
+                if (mn->ops->invalidate_range_end)
+                        mn->ops->invalidate_range_end(mn, mm, start, end);
+        }
+        rcu_read_unlock();
+}
+
+static int do_mmu_notifier_register(struct mmu_notifier *mn,
+                                    struct mm_struct *mm,
+                                    int take_mmap_sem)
+{
+        struct mmu_notifier_mm *mmu_notifier_mm;
+        int ret;
+
+        BUG_ON(atomic_read(&mm->mm_users) <= 0);
+
+        ret = -ENOMEM;
+        mmu_notifier_mm = kmalloc(sizeof(struct mmu_notifier_mm), GFP_KERNEL);
+        if (unlikely(!mmu_notifier_mm))
+                goto out;
+
+        if (take_mmap_sem)
+                down_write(&mm->mmap_sem);
+        ret = mm_take_all_locks(mm);
+        if (unlikely(ret))
+                goto out_cleanup;
+
+        if (!mm_has_notifiers(mm)) {
+                INIT_HLIST_HEAD(&mmu_notifier_mm->list);
+                spin_lock_init(&mmu_notifier_mm->lock);
+                mm->mmu_notifier_mm = mmu_notifier_mm;
+                mmu_notifier_mm = NULL;
+        }
+        atomic_inc(&mm->mm_count);
+
+        /*
+         * Serialize the update against mmu_notifier_unregister. A
+         * side note: mmu_notifier_release can't run concurrently with
+         * us because we hold the mm_users pin (either implicitly as
+         * current->mm or explicitly with get_task_mm() or similar).
+         * We can't race against any other mmu notifier method either
+         * thanks to mm_take_all_locks().
+         */
+        spin_lock(&mm->mmu_notifier_mm->lock);
+        hlist_add_head(&mn->hlist, &mm->mmu_notifier_mm->list);
+        spin_unlock(&mm->mmu_notifier_mm->lock);
+
+        mm_drop_all_locks(mm);
+out_cleanup:
+        if (take_mmap_sem)
+                up_write(&mm->mmap_sem);
+        /* kfree() does nothing if mmu_notifier_mm is NULL */
+        kfree(mmu_notifier_mm);
+out:
+        BUG_ON(atomic_read(&mm->mm_users) <= 0);
+        return ret;
+}
+
+/*
+ * Must not hold mmap_sem nor any other VM related lock when calling
+ * this registration function. Must also ensure mm_users can't go down
+ * to zero while this runs to avoid races with mmu_notifier_release,
+ * so mm has to be current->mm or the mm should be pinned safely such
+ * as with get_task_mm(). If the mm is not current->mm, the mm_users
+ * pin should be released by calling mmput after mmu_notifier_register
+ * returns. mmu_notifier_unregister must be always called to
+ * unregister the notifier. mm_count is automatically pinned to allow
+ * mmu_notifier_unregister to safely run at any time later, before or
+ * after exit_mmap. ->release will always be called before exit_mmap
+ * frees the pages.
+ */
+int mmu_notifier_register(struct mmu_notifier *mn, struct mm_struct *mm)
+{
+        return do_mmu_notifier_register(mn, mm, 1);
+}
+EXPORT_SYMBOL_GPL(mmu_notifier_register);
+
+/*
+ * Same as mmu_notifier_register but here the caller must hold the
+ * mmap_sem in write mode.
+ */
+int __mmu_notifier_register(struct mmu_notifier *mn, struct mm_struct *mm)
+{
+        return do_mmu_notifier_register(mn, mm, 0);
+}
+EXPORT_SYMBOL_GPL(__mmu_notifier_register);
+
+/* this is called after the last mmu_notifier_unregister() returned */
+void __mmu_notifier_mm_destroy(struct mm_struct *mm)
+{
+        BUG_ON(!hlist_empty(&mm->mmu_notifier_mm->list));
+        kfree(mm->mmu_notifier_mm);
+        mm->mmu_notifier_mm = LIST_POISON1; /* debug */
+}
+
+/*
+ * This releases the mm_count pin automatically and frees the mm
+ * structure if it was the last user of it. It serializes against
+ * running mmu notifiers with RCU and against mmu_notifier_unregister
+ * with the unregister lock + RCU. All sptes must be dropped before
+ * calling mmu_notifier_unregister. ->release or any other notifier
+ * method may be invoked concurrently with mmu_notifier_unregister,
+ * and only after mmu_notifier_unregister returned we're guaranteed
+ * that ->release or any other method can't run anymore.
+ */
+void mmu_notifier_unregister(struct mmu_notifier *mn, struct mm_struct *mm)
+{
+        BUG_ON(atomic_read(&mm->mm_count) <= 0);
+
+        spin_lock(&mm->mmu_notifier_mm->lock);
+        if (!hlist_unhashed(&mn->hlist)) {
+                hlist_del_rcu(&mn->hlist);
+
+                /*
+                 * RCU here will force exit_mmap to wait ->release to finish
+                 * before freeing the pages.
+                 */
+                rcu_read_lock();
+                spin_unlock(&mm->mmu_notifier_mm->lock);
+                /*
+                 * exit_mmap will block in mmu_notifier_release to
+                 * guarantee ->release is called before freeing the
+                 * pages.
+                 */
+                if (mn->ops->release)
+                        mn->ops->release(mn, mm);
+                rcu_read_unlock();
+        } else
+                spin_unlock(&mm->mmu_notifier_mm->lock);
+
+        /*
+         * Wait any running method to finish, of course including
+         * ->release if it was run by mmu_notifier_relase instead of us.
+         */
+        synchronize_rcu();
+
+        BUG_ON(atomic_read(&mm->mm_count) <= 0);
+
+        mmdrop(mm);
+}
+EXPORT_SYMBOL_GPL(mmu_notifier_unregister);
diff --git a/mm/mprotect.c b/mm/mprotect.c
index abd645a3b0a0..fded06f923f4 100644
--- 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>
@@ -203,10 +204,12 @@ success:
                 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
index 08e3c7f2bd15..1a7743923c8c 100644
--- 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 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
         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 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
         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/page_alloc.c b/mm/page_alloc.c
index 6da667274df5..3cf3d05b6bd4 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2372,7 +2372,7 @@ static void build_zonelist_cache(pg_data_t *pgdat)
 
 #endif  /* CONFIG_NUMA */
 
-/* return values int ....just for stop_machine_run() */
+/* return values int ....just for stop_machine() */
 static int __build_all_zonelists(void *dummy)
 {
         int nid;
@@ -2397,7 +2397,7 @@ void build_all_zonelists(void)
         } else {
                 /* we have to stop all cpus to guarantee there is no user
                    of zonelist */
-                stop_machine_run(__build_all_zonelists, NULL, NR_CPUS);
+                stop_machine(__build_all_zonelists, NULL, NULL);
                 /* cpuset refresh routine should be here */
         }
         vm_total_pages = nr_free_pagecache_pages();
diff --git a/mm/rmap.c b/mm/rmap.c
index 39ae5a9bf382..99bc3f9cd796 100644
--- 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 @@ static int page_referenced_one(struct page *page,
         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
@@ -457,7 +458,7 @@ static int page_mkclean_one(struct page *page, struct vm_area_struct *vma)
                 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);
@@ -705,14 +706,14 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
          * 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))
@@ -837,12 +838,12 @@ static void try_to_unmap_cluster(unsigned long cursor,
                 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))
diff --git a/mm/shmem.c b/mm/shmem.c
index 952d361774bb..c1e5a3b4f758 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1513,7 +1513,6 @@ shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
                 inode->i_uid = current->fsuid;
                 inode->i_gid = current->fsgid;
                 inode->i_blocks = 0;
-                inode->i_mapping->a_ops = &shmem_aops;
                 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
                 inode->i_generation = get_seconds();
@@ -1528,6 +1527,7 @@ shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
                         init_special_inode(inode, mode, dev);
                         break;
                 case S_IFREG:
+                        inode->i_mapping->a_ops = &shmem_aops;
                         inode->i_op = &shmem_inode_operations;
                         inode->i_fop = &shmem_file_operations;
                         mpol_shared_policy_init(&info->policy,
@@ -1929,6 +1929,7 @@ static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *s
                         return error;
                 }
                 unlock_page(page);
+                inode->i_mapping->a_ops = &shmem_aops;
                 inode->i_op = &shmem_symlink_inode_operations;
                 kaddr = kmap_atomic(page, KM_USER0);
                 memcpy(kaddr, symname, len);