mm: swap: implement generic handler for swap_activate
[linux-3.10.git] / mm / nommu.c
index 88ff091..d4b0c10 100644 (file)
  *  Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com>
  *  Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
  *  Copyright (c) 2002      Greg Ungerer <gerg@snapgear.com>
- *  Copyright (c) 2007-2009 Paul Mundt <lethal@linux-sh.org>
+ *  Copyright (c) 2007-2010 Paul Mundt <lethal@linux-sh.org>
  */
 
-#include <linux/module.h>
+#include <linux/export.h>
 #include <linux/mm.h>
 #include <linux/mman.h>
 #include <linux/swap.h>
 #include <linux/pagemap.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
-#include <linux/tracehook.h>
 #include <linux/blkdev.h>
 #include <linux/backing-dev.h>
 #include <linux/mount.h>
 #include <linux/personality.h>
 #include <linux/security.h>
 #include <linux/syscalls.h>
+#include <linux/audit.h>
 
 #include <asm/uaccess.h>
 #include <asm/tlb.h>
@@ -126,7 +126,8 @@ unsigned int kobjsize(const void *objp)
 
 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
                     unsigned long start, int nr_pages, unsigned int foll_flags,
-                    struct page **pages, struct vm_area_struct **vmas)
+                    struct page **pages, struct vm_area_struct **vmas,
+                    int *retry)
 {
        struct vm_area_struct *vma;
        unsigned long vm_flags;
@@ -184,7 +185,8 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
        if (force)
                flags |= FOLL_FORCE;
 
-       return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas);
+       return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
+                               NULL);
 }
 EXPORT_SYMBOL(get_user_pages);
 
@@ -293,12 +295,60 @@ void *vmalloc(unsigned long size)
 }
 EXPORT_SYMBOL(vmalloc);
 
+/*
+ *     vzalloc - allocate virtually continguos memory with zero fill
+ *
+ *     @size:          allocation size
+ *
+ *     Allocate enough pages to cover @size from the page level
+ *     allocator and map them into continguos kernel virtual space.
+ *     The memory allocated is set to zero.
+ *
+ *     For tight control over page level allocator and protection flags
+ *     use __vmalloc() instead.
+ */
+void *vzalloc(unsigned long size)
+{
+       return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
+                       PAGE_KERNEL);
+}
+EXPORT_SYMBOL(vzalloc);
+
+/**
+ * vmalloc_node - allocate memory on a specific node
+ * @size:      allocation size
+ * @node:      numa node
+ *
+ * Allocate enough pages to cover @size from the page level
+ * allocator and map them into contiguous kernel virtual space.
+ *
+ * For tight control over page level allocator and protection flags
+ * use __vmalloc() instead.
+ */
 void *vmalloc_node(unsigned long size, int node)
 {
        return vmalloc(size);
 }
 EXPORT_SYMBOL(vmalloc_node);
 
+/**
+ * vzalloc_node - allocate memory on a specific node with zero fill
+ * @size:      allocation size
+ * @node:      numa node
+ *
+ * Allocate enough pages to cover @size from the page level
+ * allocator and map them into contiguous kernel virtual space.
+ * The memory allocated is set to zero.
+ *
+ * For tight control over page level allocator and protection flags
+ * use __vmalloc() instead.
+ */
+void *vzalloc_node(unsigned long size, int node)
+{
+       return vzalloc(size);
+}
+EXPORT_SYMBOL(vzalloc_node);
+
 #ifndef PAGE_KERNEL_EXEC
 # define PAGE_KERNEL_EXEC PAGE_KERNEL
 #endif
@@ -392,6 +442,31 @@ void  __attribute__((weak)) vmalloc_sync_all(void)
 {
 }
 
+/**
+ *     alloc_vm_area - allocate a range of kernel address space
+ *     @size:          size of the area
+ *
+ *     Returns:        NULL on failure, vm_struct on success
+ *
+ *     This function reserves a range of kernel address space, and
+ *     allocates pagetables to map that range.  No actual mappings
+ *     are created.  If the kernel address space is not shared
+ *     between processes, it syncs the pagetable across all
+ *     processes.
+ */
+struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)
+{
+       BUG();
+       return NULL;
+}
+EXPORT_SYMBOL_GPL(alloc_vm_area);
+
+void free_vm_area(struct vm_struct *area)
+{
+       BUG();
+}
+EXPORT_SYMBOL_GPL(free_vm_area);
+
 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
                   struct page *page)
 {
@@ -604,9 +679,9 @@ static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
  */
 static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
 {
-       struct vm_area_struct *pvma, **pp, *next;
+       struct vm_area_struct *pvma, *prev;
        struct address_space *mapping;
-       struct rb_node **p, *parent;
+       struct rb_node **p, *parent, *rb_prev;
 
        kenter(",%p", vma);
 
@@ -621,13 +696,15 @@ static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
        if (vma->vm_file) {
                mapping = vma->vm_file->f_mapping;
 
+               mutex_lock(&mapping->i_mmap_mutex);
                flush_dcache_mmap_lock(mapping);
                vma_prio_tree_insert(vma, &mapping->i_mmap);
                flush_dcache_mmap_unlock(mapping);
+               mutex_unlock(&mapping->i_mmap_mutex);
        }
 
        /* add the VMA to the tree */
-       parent = NULL;
+       parent = rb_prev = NULL;
        p = &mm->mm_rb.rb_node;
        while (*p) {
                parent = *p;
@@ -637,17 +714,20 @@ static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
                 * (the latter is necessary as we may get identical VMAs) */
                if (vma->vm_start < pvma->vm_start)
                        p = &(*p)->rb_left;
-               else if (vma->vm_start > pvma->vm_start)
+               else if (vma->vm_start > pvma->vm_start) {
+                       rb_prev = parent;
                        p = &(*p)->rb_right;
-               else if (vma->vm_end < pvma->vm_end)
+               } else if (vma->vm_end < pvma->vm_end)
                        p = &(*p)->rb_left;
-               else if (vma->vm_end > pvma->vm_end)
+               else if (vma->vm_end > pvma->vm_end) {
+                       rb_prev = parent;
                        p = &(*p)->rb_right;
-               else if (vma < pvma)
+               } else if (vma < pvma)
                        p = &(*p)->rb_left;
-               else if (vma > pvma)
+               else if (vma > pvma) {
+                       rb_prev = parent;
                        p = &(*p)->rb_right;
-               else
+               } else
                        BUG();
        }
 
@@ -655,20 +735,11 @@ static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
        rb_insert_color(&vma->vm_rb, &mm->mm_rb);
 
        /* add VMA to the VMA list also */
-       for (pp = &mm->mmap; (pvma = *pp); pp = &(*pp)->vm_next) {
-               if (pvma->vm_start > vma->vm_start)
-                       break;
-               if (pvma->vm_start < vma->vm_start)
-                       continue;
-               if (pvma->vm_end < vma->vm_end)
-                       break;
-       }
+       prev = NULL;
+       if (rb_prev)
+               prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
 
-       next = *pp;
-       *pp = vma;
-       vma->vm_next = next;
-       if (next)
-               next->vm_prev = vma;
+       __vma_link_list(mm, vma, prev, parent);
 }
 
 /*
@@ -676,7 +747,6 @@ static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
  */
 static void delete_vma_from_mm(struct vm_area_struct *vma)
 {
-       struct vm_area_struct **pp;
        struct address_space *mapping;
        struct mm_struct *mm = vma->vm_mm;
 
@@ -692,21 +762,23 @@ static void delete_vma_from_mm(struct vm_area_struct *vma)
        if (vma->vm_file) {
                mapping = vma->vm_file->f_mapping;
 
+               mutex_lock(&mapping->i_mmap_mutex);
                flush_dcache_mmap_lock(mapping);
                vma_prio_tree_remove(vma, &mapping->i_mmap);
                flush_dcache_mmap_unlock(mapping);
+               mutex_unlock(&mapping->i_mmap_mutex);
        }
 
        /* remove from the MM's tree and list */
        rb_erase(&vma->vm_rb, &mm->mm_rb);
-       for (pp = &mm->mmap; *pp; pp = &(*pp)->vm_next) {
-               if (*pp == vma) {
-                       *pp = vma->vm_next;
-                       break;
-               }
-       }
 
-       vma->vm_mm = NULL;
+       if (vma->vm_prev)
+               vma->vm_prev->vm_next = vma->vm_next;
+       else
+               mm->mmap = vma->vm_next;
+
+       if (vma->vm_next)
+               vma->vm_next->vm_prev = vma->vm_prev;
 }
 
 /*
@@ -733,17 +805,15 @@ static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
 {
        struct vm_area_struct *vma;
-       struct rb_node *n = mm->mm_rb.rb_node;
 
        /* check the cache first */
        vma = mm->mmap_cache;
        if (vma && vma->vm_start <= addr && vma->vm_end > addr)
                return vma;
 
-       /* trawl the tree (there may be multiple mappings in which addr
+       /* trawl the list (there may be multiple mappings in which addr
         * resides) */
-       for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) {
-               vma = rb_entry(n, struct vm_area_struct, vm_rb);
+       for (vma = mm->mmap; vma; vma = vma->vm_next) {
                if (vma->vm_start > addr)
                        return NULL;
                if (vma->vm_end > addr) {
@@ -783,7 +853,6 @@ static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
                                             unsigned long len)
 {
        struct vm_area_struct *vma;
-       struct rb_node *n = mm->mm_rb.rb_node;
        unsigned long end = addr + len;
 
        /* check the cache first */
@@ -791,10 +860,9 @@ static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
        if (vma && vma->vm_start == addr && vma->vm_end == end)
                return vma;
 
-       /* trawl the tree (there may be multiple mappings in which addr
+       /* trawl the list (there may be multiple mappings in which addr
         * resides) */
-       for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) {
-               vma = rb_entry(n, struct vm_area_struct, vm_rb);
+       for (vma = mm->mmap; vma; vma = vma->vm_next) {
                if (vma->vm_start < addr)
                        continue;
                if (vma->vm_start > addr)
@@ -821,7 +889,6 @@ static int validate_mmap_request(struct file *file,
                                 unsigned long *_capabilities)
 {
        unsigned long capabilities, rlen;
-       unsigned long reqprot = prot;
        int ret;
 
        /* do the simple checks first */
@@ -979,7 +1046,7 @@ static int validate_mmap_request(struct file *file,
        }
 
        /* allow the security API to have its say */
-       ret = security_file_mmap(file, reqprot, prot, flags, addr, 0);
+       ret = security_mmap_addr(addr);
        if (ret < 0)
                return ret;
 
@@ -1020,7 +1087,7 @@ static unsigned long determine_vm_flags(struct file *file,
         * it's being traced - otherwise breakpoints set in it may interfere
         * with another untraced process
         */
-       if ((flags & MAP_PRIVATE) && tracehook_expect_breakpoints(current))
+       if ((flags & MAP_PRIVATE) && current->ptrace)
                vm_flags &= ~VM_MAYSHARE;
 
        return vm_flags;
@@ -1057,7 +1124,7 @@ static int do_mmap_private(struct vm_area_struct *vma,
                           unsigned long capabilities)
 {
        struct page *pages;
-       unsigned long total, point, n, rlen;
+       unsigned long total, point, n;
        void *base;
        int ret, order;
 
@@ -1081,13 +1148,12 @@ static int do_mmap_private(struct vm_area_struct *vma,
                 * make a private copy of the data and map that instead */
        }
 
-       rlen = PAGE_ALIGN(len);
 
        /* allocate some memory to hold the mapping
         * - note that this may not return a page-aligned address if the object
         *   we're allocating is smaller than a page
         */
-       order = get_order(rlen);
+       order = get_order(len);
        kdebug("alloc order %d for %lx", order, len);
 
        pages = alloc_pages(GFP_KERNEL, order);
@@ -1097,7 +1163,7 @@ static int do_mmap_private(struct vm_area_struct *vma,
        total = 1 << order;
        atomic_long_add(total, &mmap_pages_allocated);
 
-       point = rlen >> PAGE_SHIFT;
+       point = len >> PAGE_SHIFT;
 
        /* we allocated a power-of-2 sized page set, so we may want to trim off
         * the excess */
@@ -1119,7 +1185,7 @@ static int do_mmap_private(struct vm_area_struct *vma,
        base = page_address(pages);
        region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
        region->vm_start = (unsigned long) base;
-       region->vm_end   = region->vm_start + rlen;
+       region->vm_end   = region->vm_start + len;
        region->vm_top   = region->vm_start + (total << PAGE_SHIFT);
 
        vma->vm_start = region->vm_start;
@@ -1135,22 +1201,22 @@ static int do_mmap_private(struct vm_area_struct *vma,
 
                old_fs = get_fs();
                set_fs(KERNEL_DS);
-               ret = vma->vm_file->f_op->read(vma->vm_file, base, rlen, &fpos);
+               ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
                set_fs(old_fs);
 
                if (ret < 0)
                        goto error_free;
 
                /* clear the last little bit */
-               if (ret < rlen)
-                       memset(base + ret, 0, rlen - ret);
+               if (ret < len)
+                       memset(base + ret, 0, len - ret);
 
        }
 
        return 0;
 
 error_free:
-       free_page_series(region->vm_start, region->vm_end);
+       free_page_series(region->vm_start, region->vm_top);
        region->vm_start = vma->vm_start = 0;
        region->vm_end   = vma->vm_end = 0;
        region->vm_top   = 0;
@@ -1159,7 +1225,7 @@ error_free:
 enomem:
        printk("Allocation of length %lu from process %d (%s) failed\n",
               len, current->pid, current->comm);
-       show_free_areas();
+       show_free_areas(0);
        return -ENOMEM;
 }
 
@@ -1192,6 +1258,7 @@ unsigned long do_mmap_pgoff(struct file *file,
 
        /* we ignore the address hint */
        addr = 0;
+       len = PAGE_ALIGN(len);
 
        /* we've determined that we can make the mapping, now translate what we
         * now know into VMA flags */
@@ -1309,15 +1376,15 @@ unsigned long do_mmap_pgoff(struct file *file,
                if (capabilities & BDI_CAP_MAP_DIRECT) {
                        addr = file->f_op->get_unmapped_area(file, addr, len,
                                                             pgoff, flags);
-                       if (IS_ERR((void *) addr)) {
+                       if (IS_ERR_VALUE(addr)) {
                                ret = addr;
-                               if (ret != (unsigned long) -ENOSYS)
+                               if (ret != -ENOSYS)
                                        goto error_just_free;
 
                                /* the driver refused to tell us where to site
                                 * the mapping so we'll have to attempt to copy
                                 * it */
-                               ret = (unsigned long) -ENODEV;
+                               ret = -ENODEV;
                                if (!(capabilities & BDI_CAP_MAP_COPY))
                                        goto error_just_free;
 
@@ -1392,17 +1459,16 @@ error_getting_vma:
        printk(KERN_WARNING "Allocation of vma for %lu byte allocation"
               " from process %d failed\n",
               len, current->pid);
-       show_free_areas();
+       show_free_areas(0);
        return -ENOMEM;
 
 error_getting_region:
        printk(KERN_WARNING "Allocation of vm region for %lu byte allocation"
               " from process %d failed\n",
               len, current->pid);
-       show_free_areas();
+       show_free_areas(0);
        return -ENOMEM;
 }
-EXPORT_SYMBOL(do_mmap_pgoff);
 
 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
                unsigned long, prot, unsigned long, flags,
@@ -1411,6 +1477,7 @@ SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
        struct file *file = NULL;
        unsigned long retval = -EBADF;
 
+       audit_mmap_fd(fd, flags);
        if (!(flags & MAP_ANONYMOUS)) {
                file = fget(fd);
                if (!file)
@@ -1419,9 +1486,7 @@ SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
 
        flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
 
-       down_write(&current->mm->mmap_sem);
-       retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
-       up_write(&current->mm->mmap_sem);
+       retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
 
        if (file)
                fput(file);
@@ -1567,15 +1632,17 @@ static int shrink_vma(struct mm_struct *mm,
 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
 {
        struct vm_area_struct *vma;
-       struct rb_node *rb;
-       unsigned long end = start + len;
+       unsigned long end;
        int ret;
 
        kenter(",%lx,%zx", start, len);
 
+       len = PAGE_ALIGN(len);
        if (len == 0)
                return -EINVAL;
 
+       end = start + len;
+
        /* find the first potentially overlapping VMA */
        vma = find_vma(mm, start);
        if (!vma) {
@@ -1600,9 +1667,8 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
                        }
                        if (end == vma->vm_end)
                                goto erase_whole_vma;
-                       rb = rb_next(&vma->vm_rb);
-                       vma = rb_entry(rb, struct vm_area_struct, vm_rb);
-               } while (rb);
+                       vma = vma->vm_next;
+               } while (vma);
                kleave(" = -EINVAL [split file]");
                return -EINVAL;
        } else {
@@ -1639,16 +1705,22 @@ erase_whole_vma:
 }
 EXPORT_SYMBOL(do_munmap);
 
-SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
+int vm_munmap(unsigned long addr, size_t len)
 {
-       int ret;
        struct mm_struct *mm = current->mm;
+       int ret;
 
        down_write(&mm->mmap_sem);
        ret = do_munmap(mm, addr, len);
        up_write(&mm->mmap_sem);
        return ret;
 }
+EXPORT_SYMBOL(vm_munmap);
+
+SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
+{
+       return vm_munmap(addr, len);
+}
 
 /*
  * release all the mappings made in a process's VM space
@@ -1668,12 +1740,13 @@ void exit_mmap(struct mm_struct *mm)
                mm->mmap = vma->vm_next;
                delete_vma_from_mm(vma);
                delete_vma(mm, vma);
+               cond_resched();
        }
 
        kleave("");
 }
 
-unsigned long do_brk(unsigned long addr, unsigned long len)
+unsigned long vm_brk(unsigned long addr, unsigned long len)
 {
        return -ENOMEM;
 }
@@ -1695,6 +1768,8 @@ unsigned long do_mremap(unsigned long addr,
        struct vm_area_struct *vma;
 
        /* insanity checks first */
+       old_len = PAGE_ALIGN(old_len);
+       new_len = PAGE_ALIGN(new_len);
        if (old_len == 0 || new_len == 0)
                return (unsigned long) -EINVAL;
 
@@ -1741,10 +1816,13 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
        return NULL;
 }
 
-int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
-               unsigned long to, unsigned long size, pgprot_t prot)
+int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
+               unsigned long pfn, unsigned long size, pgprot_t prot)
 {
-       vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
+       if (addr != (pfn << PAGE_SHIFT))
+               return -EINVAL;
+
+       vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
        return 0;
 }
 EXPORT_SYMBOL(remap_pfn_range);
@@ -1764,10 +1842,6 @@ int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
 }
 EXPORT_SYMBOL(remap_vmalloc_range);
 
-void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
-{
-}
-
 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
        unsigned long len, unsigned long pgoff, unsigned long flags)
 {
@@ -1814,9 +1888,17 @@ int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
                return 0;
 
        if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
-               unsigned long n;
+               free = global_page_state(NR_FREE_PAGES);
+               free += global_page_state(NR_FILE_PAGES);
+
+               /*
+                * shmem pages shouldn't be counted as free in this
+                * case, they can't be purged, only swapped out, and
+                * that won't affect the overall amount of available
+                * memory in the system.
+                */
+               free -= global_page_state(NR_SHMEM);
 
-               free = global_page_state(NR_FILE_PAGES);
                free += nr_swap_pages;
 
                /*
@@ -1828,34 +1910,18 @@ int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
                free += global_page_state(NR_SLAB_RECLAIMABLE);
 
                /*
-                * Leave the last 3% for root
-                */
-               if (!cap_sys_admin)
-                       free -= free / 32;
-
-               if (free > pages)
-                       return 0;
-
-               /*
-                * nr_free_pages() is very expensive on large systems,
-                * only call if we're about to fail.
-                */
-               n = nr_free_pages();
-
-               /*
                 * Leave reserved pages. The pages are not for anonymous pages.
                 */
-               if (n <= totalreserve_pages)
+               if (free <= totalreserve_pages)
                        goto error;
                else
-                       n -= totalreserve_pages;
+                       free -= totalreserve_pages;
 
                /*
                 * Leave the last 3% for root
                 */
                if (!cap_sys_admin)
-                       n -= n / 32;
-               free += n;
+                       free -= free / 32;
 
                if (free > pages)
                        return 0;
@@ -1885,7 +1951,7 @@ error:
        return -ENOMEM;
 }
 
-int in_gate_area_no_task(unsigned long addr)
+int in_gate_area_no_mm(unsigned long addr)
 {
        return 0;
 }
@@ -1897,21 +1963,10 @@ int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 }
 EXPORT_SYMBOL(filemap_fault);
 
-/*
- * Access another process' address space.
- * - source/target buffer must be kernel space
- */
-int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
+static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
+               unsigned long addr, void *buf, int len, int write)
 {
        struct vm_area_struct *vma;
-       struct mm_struct *mm;
-
-       if (addr + len < addr)
-               return 0;
-
-       mm = get_task_mm(tsk);
-       if (!mm)
-               return 0;
 
        down_read(&mm->mmap_sem);
 
@@ -1936,6 +1991,43 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in
        }
 
        up_read(&mm->mmap_sem);
+
+       return len;
+}
+
+/**
+ * @access_remote_vm - access another process' address space
+ * @mm:                the mm_struct of the target address space
+ * @addr:      start address to access
+ * @buf:       source or destination buffer
+ * @len:       number of bytes to transfer
+ * @write:     whether the access is a write
+ *
+ * The caller must hold a reference on @mm.
+ */
+int access_remote_vm(struct mm_struct *mm, unsigned long addr,
+               void *buf, int len, int write)
+{
+       return __access_remote_vm(NULL, mm, addr, buf, len, write);
+}
+
+/*
+ * Access another process' address space.
+ * - source/target buffer must be kernel space
+ */
+int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
+{
+       struct mm_struct *mm;
+
+       if (addr + len < addr)
+               return 0;
+
+       mm = get_task_mm(tsk);
+       if (!mm)
+               return 0;
+
+       len = __access_remote_vm(tsk, mm, addr, buf, len, write);
+
        mmput(mm);
        return len;
 }
@@ -1964,6 +2056,7 @@ int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
        high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 
        down_write(&nommu_region_sem);
+       mutex_lock(&inode->i_mapping->i_mmap_mutex);
 
        /* search for VMAs that fall within the dead zone */
        vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
@@ -1971,6 +2064,7 @@ int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
                /* found one - only interested if it's shared out of the page
                 * cache */
                if (vma->vm_flags & VM_SHARED) {
+                       mutex_unlock(&inode->i_mapping->i_mmap_mutex);
                        up_write(&nommu_region_sem);
                        return -ETXTBSY; /* not quite true, but near enough */
                }
@@ -1998,6 +2092,7 @@ int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
                }
        }
 
+       mutex_unlock(&inode->i_mapping->i_mmap_mutex);
        up_write(&nommu_region_sem);
        return 0;
 }