1 files changed, 1138 insertions, 0 deletions

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
new file mode 100644
index 000000000000..a3b44a671cec
--- /dev/null
+++ b/mm/mempolicy.c
@@ -0,0 +1,1138 @@
+/*
+ * Simple NUMA memory policy for the Linux kernel.
+ *
+ * Copyright 2003,2004 Andi Kleen, SuSE Labs.
+ * Subject to the GNU Public License, version 2.
+ *
+ * NUMA policy allows the user to give hints in which node(s) memory should
+ * be allocated.
+ *
+ * Support four policies per VMA and per process:
+ *
+ * The VMA policy has priority over the process policy for a page fault.
+ *
+ * interleave     Allocate memory interleaved over a set of nodes,
+ *                with normal fallback if it fails.
+ *                For VMA based allocations this interleaves based on the
+ *                offset into the backing object or offset into the mapping
+ *                for anonymous memory. For process policy an process counter
+ *                is used.
+ * bind           Only allocate memory on a specific set of nodes,
+ *                no fallback.
+ * preferred       Try a specific node first before normal fallback.
+ *                As a special case node -1 here means do the allocation
+ *                on the local CPU. This is normally identical to default,
+ *                but useful to set in a VMA when you have a non default
+ *                process policy.
+ * default        Allocate on the local node first, or when on a VMA
+ *                use the process policy. This is what Linux always did
+ *                in a NUMA aware kernel and still does by, ahem, default.
+ *
+ * The process policy is applied for most non interrupt memory allocations
+ * in that process' context. Interrupts ignore the policies and always
+ * try to allocate on the local CPU. The VMA policy is only applied for memory
+ * allocations for a VMA in the VM.
+ *
+ * Currently there are a few corner cases in swapping where the policy
+ * is not applied, but the majority should be handled. When process policy
+ * is used it is not remembered over swap outs/swap ins.
+ *
+ * Only the highest zone in the zone hierarchy gets policied. Allocations
+ * requesting a lower zone just use default policy. This implies that
+ * on systems with highmem kernel lowmem allocation don't get policied.
+ * Same with GFP_DMA allocations.
+ *
+ * For shmfs/tmpfs/hugetlbfs shared memory the policy is shared between
+ * all users and remembered even when nobody has memory mapped.
+ */
+
+/* Notebook:
+   fix mmap readahead to honour policy and enable policy for any page cache
+   object
+   statistics for bigpages
+   global policy for page cache? currently it uses process policy. Requires
+   first item above.
+   handle mremap for shared memory (currently ignored for the policy)
+   grows down?
+   make bind policy root only? It can trigger oom much faster and the
+   kernel is not always grateful with that.
+   could replace all the switch()es with a mempolicy_ops structure.
+*/
+
+#include <linux/mempolicy.h>
+#include <linux/mm.h>
+#include <linux/highmem.h>
+#include <linux/hugetlb.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/nodemask.h>
+#include <linux/cpuset.h>
+#include <linux/gfp.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/compat.h>
+#include <linux/mempolicy.h>
+#include <asm/tlbflush.h>
+#include <asm/uaccess.h>
+
+static kmem_cache_t *policy_cache;
+static kmem_cache_t *sn_cache;
+
+#define PDprintk(fmt...)
+
+/* Highest zone. An specific allocation for a zone below that is not
+   policied. */
+static int policy_zone;
+
+static struct mempolicy default_policy = {
+        .refcnt = ATOMIC_INIT(1), /* never free it */
+        .policy = MPOL_DEFAULT,
+};
+
+/* Check if all specified nodes are online */
+static int nodes_online(unsigned long *nodes)
+{
+        DECLARE_BITMAP(online2, MAX_NUMNODES);
+
+        bitmap_copy(online2, nodes_addr(node_online_map), MAX_NUMNODES);
+        if (bitmap_empty(online2, MAX_NUMNODES))
+                set_bit(0, online2);
+        if (!bitmap_subset(nodes, online2, MAX_NUMNODES))
+                return -EINVAL;
+        return 0;
+}
+
+/* Do sanity checking on a policy */
+static int mpol_check_policy(int mode, unsigned long *nodes)
+{
+        int empty = bitmap_empty(nodes, MAX_NUMNODES);
+
+        switch (mode) {
+        case MPOL_DEFAULT:
+                if (!empty)
+                        return -EINVAL;
+                break;
+        case MPOL_BIND:
+        case MPOL_INTERLEAVE:
+                /* Preferred will only use the first bit, but allow
+                   more for now. */
+                if (empty)
+                        return -EINVAL;
+                break;
+        }
+        return nodes_online(nodes);
+}
+
+/* Copy a node mask from user space. */
+static int get_nodes(unsigned long *nodes, unsigned long __user *nmask,
+                     unsigned long maxnode, int mode)
+{
+        unsigned long k;
+        unsigned long nlongs;
+        unsigned long endmask;
+
+        --maxnode;
+        bitmap_zero(nodes, MAX_NUMNODES);
+        if (maxnode == 0 || !nmask)
+                return 0;
+
+        nlongs = BITS_TO_LONGS(maxnode);
+        if ((maxnode % BITS_PER_LONG) == 0)
+                endmask = ~0UL;
+        else
+                endmask = (1UL << (maxnode % BITS_PER_LONG)) - 1;
+
+        /* When the user specified more nodes than supported just check
+           if the non supported part is all zero. */
+        if (nlongs > BITS_TO_LONGS(MAX_NUMNODES)) {
+                if (nlongs > PAGE_SIZE/sizeof(long))
+                        return -EINVAL;
+                for (k = BITS_TO_LONGS(MAX_NUMNODES); k < nlongs; k++) {
+                        unsigned long t;
+                        if (get_user(t,  nmask + k))
+                                return -EFAULT;
+                        if (k == nlongs - 1) {
+                                if (t & endmask)
+                                        return -EINVAL;
+                        } else if (t)
+                                return -EINVAL;
+                }
+                nlongs = BITS_TO_LONGS(MAX_NUMNODES);
+                endmask = ~0UL;
+        }
+
+        if (copy_from_user(nodes, nmask, nlongs*sizeof(unsigned long)))
+                return -EFAULT;
+        nodes[nlongs-1] &= endmask;
+        /* Update current mems_allowed */
+        cpuset_update_current_mems_allowed();
+        /* Ignore nodes not set in current->mems_allowed */
+        cpuset_restrict_to_mems_allowed(nodes);
+        return mpol_check_policy(mode, nodes);
+}
+
+/* Generate a custom zonelist for the BIND policy. */
+static struct zonelist *bind_zonelist(unsigned long *nodes)
+{
+        struct zonelist *zl;
+        int num, max, nd;
+
+        max = 1 + MAX_NR_ZONES * bitmap_weight(nodes, MAX_NUMNODES);
+        zl = kmalloc(sizeof(void *) * max, GFP_KERNEL);
+        if (!zl)
+                return NULL;
+        num = 0;
+        for (nd = find_first_bit(nodes, MAX_NUMNODES);
+             nd < MAX_NUMNODES;
+             nd = find_next_bit(nodes, MAX_NUMNODES, 1+nd)) {
+                int k;
+                for (k = MAX_NR_ZONES-1; k >= 0; k--) {
+                        struct zone *z = &NODE_DATA(nd)->node_zones[k];
+                        if (!z->present_pages)
+                                continue;
+                        zl->zones[num++] = z;
+                        if (k > policy_zone)
+                                policy_zone = k;
+                }
+        }
+        BUG_ON(num >= max);
+        zl->zones[num] = NULL;
+        return zl;
+}
+
+/* Create a new policy */
+static struct mempolicy *mpol_new(int mode, unsigned long *nodes)
+{
+        struct mempolicy *policy;
+
+        PDprintk("setting mode %d nodes[0] %lx\n", mode, nodes[0]);
+        if (mode == MPOL_DEFAULT)
+                return NULL;
+        policy = kmem_cache_alloc(policy_cache, GFP_KERNEL);
+        if (!policy)
+                return ERR_PTR(-ENOMEM);
+        atomic_set(&policy->refcnt, 1);
+        switch (mode) {
+        case MPOL_INTERLEAVE:
+                bitmap_copy(policy->v.nodes, nodes, MAX_NUMNODES);
+                break;
+        case MPOL_PREFERRED:
+                policy->v.preferred_node = find_first_bit(nodes, MAX_NUMNODES);
+                if (policy->v.preferred_node >= MAX_NUMNODES)
+                        policy->v.preferred_node = -1;
+                break;
+        case MPOL_BIND:
+                policy->v.zonelist = bind_zonelist(nodes);
+                if (policy->v.zonelist == NULL) {
+                        kmem_cache_free(policy_cache, policy);
+                        return ERR_PTR(-ENOMEM);
+                }
+                break;
+        }
+        policy->policy = mode;
+        return policy;
+}
+
+/* Ensure all existing pages follow the policy. */
+static int
+verify_pages(struct mm_struct *mm,
+             unsigned long addr, unsigned long end, unsigned long *nodes)
+{
+        while (addr < end) {
+                struct page *p;
+                pte_t *pte;
+                pmd_t *pmd;
+                pud_t *pud;
+                pgd_t *pgd;
+                pgd = pgd_offset(mm, addr);
+                if (pgd_none(*pgd)) {
+                        unsigned long next = (addr + PGDIR_SIZE) & PGDIR_MASK;
+                        if (next > addr)
+                                break;
+                        addr = next;
+                        continue;
+                }
+                pud = pud_offset(pgd, addr);
+                if (pud_none(*pud)) {
+                        addr = (addr + PUD_SIZE) & PUD_MASK;
+                        continue;
+                }
+                pmd = pmd_offset(pud, addr);
+                if (pmd_none(*pmd)) {
+                        addr = (addr + PMD_SIZE) & PMD_MASK;
+                        continue;
+                }
+                p = NULL;
+                pte = pte_offset_map(pmd, addr);
+                if (pte_present(*pte))
+                        p = pte_page(*pte);
+                pte_unmap(pte);
+                if (p) {
+                        unsigned nid = page_to_nid(p);
+                        if (!test_bit(nid, nodes))
+                                return -EIO;
+                }
+                addr += PAGE_SIZE;
+        }
+        return 0;
+}
+
+/* Step 1: check the range */
+static struct vm_area_struct *
+check_range(struct mm_struct *mm, unsigned long start, unsigned long end,
+            unsigned long *nodes, unsigned long flags)
+{
+        int err;
+        struct vm_area_struct *first, *vma, *prev;
+
+        first = find_vma(mm, start);
+        if (!first)
+                return ERR_PTR(-EFAULT);
+        prev = NULL;
+        for (vma = first; vma && vma->vm_start < end; vma = vma->vm_next) {
+                if (!vma->vm_next && vma->vm_end < end)
+                        return ERR_PTR(-EFAULT);
+                if (prev && prev->vm_end < vma->vm_start)
+                        return ERR_PTR(-EFAULT);
+                if ((flags & MPOL_MF_STRICT) && !is_vm_hugetlb_page(vma)) {
+                        err = verify_pages(vma->vm_mm,
+                                           vma->vm_start, vma->vm_end, nodes);
+                        if (err) {
+                                first = ERR_PTR(err);
+                                break;
+                        }
+                }
+                prev = vma;
+        }
+        return first;
+}
+
+/* Apply policy to a single VMA */
+static int policy_vma(struct vm_area_struct *vma, struct mempolicy *new)
+{
+        int err = 0;
+        struct mempolicy *old = vma->vm_policy;
+
+        PDprintk("vma %lx-%lx/%lx vm_ops %p vm_file %p set_policy %p\n",
+                 vma->vm_start, vma->vm_end, vma->vm_pgoff,
+                 vma->vm_ops, vma->vm_file,
+                 vma->vm_ops ? vma->vm_ops->set_policy : NULL);
+
+        if (vma->vm_ops && vma->vm_ops->set_policy)
+                err = vma->vm_ops->set_policy(vma, new);
+        if (!err) {
+                mpol_get(new);
+                vma->vm_policy = new;
+                mpol_free(old);
+        }
+        return err;
+}
+
+/* Step 2: apply policy to a range and do splits. */
+static int mbind_range(struct vm_area_struct *vma, unsigned long start,
+                       unsigned long end, struct mempolicy *new)
+{
+        struct vm_area_struct *next;
+        int err;
+
+        err = 0;
+        for (; vma && vma->vm_start < end; vma = next) {
+                next = vma->vm_next;
+                if (vma->vm_start < start)
+                        err = split_vma(vma->vm_mm, vma, start, 1);
+                if (!err && vma->vm_end > end)
+                        err = split_vma(vma->vm_mm, vma, end, 0);
+                if (!err)
+                        err = policy_vma(vma, new);
+                if (err)
+                        break;
+        }
+        return err;
+}
+
+/* Change policy for a memory range */
+asmlinkage long sys_mbind(unsigned long start, unsigned long len,
+                          unsigned long mode,
+                          unsigned long __user *nmask, unsigned long maxnode,
+                          unsigned flags)
+{
+        struct vm_area_struct *vma;
+        struct mm_struct *mm = current->mm;
+        struct mempolicy *new;
+        unsigned long end;
+        DECLARE_BITMAP(nodes, MAX_NUMNODES);
+        int err;
+
+        if ((flags & ~(unsigned long)(MPOL_MF_STRICT)) || mode > MPOL_MAX)
+                return -EINVAL;
+        if (start & ~PAGE_MASK)
+                return -EINVAL;
+        if (mode == MPOL_DEFAULT)
+                flags &= ~MPOL_MF_STRICT;
+        len = (len + PAGE_SIZE - 1) & PAGE_MASK;
+        end = start + len;
+        if (end < start)
+                return -EINVAL;
+        if (end == start)
+                return 0;
+
+        err = get_nodes(nodes, nmask, maxnode, mode);
+        if (err)
+                return err;
+
+        new = mpol_new(mode, nodes);
+        if (IS_ERR(new))
+                return PTR_ERR(new);
+
+        PDprintk("mbind %lx-%lx mode:%ld nodes:%lx\n",start,start+len,
+                        mode,nodes[0]);
+
+        down_write(&mm->mmap_sem);
+        vma = check_range(mm, start, end, nodes, flags);
+        err = PTR_ERR(vma);
+        if (!IS_ERR(vma))
+                err = mbind_range(vma, start, end, new);
+        up_write(&mm->mmap_sem);
+        mpol_free(new);
+        return err;
+}
+
+/* Set the process memory policy */
+asmlinkage long sys_set_mempolicy(int mode, unsigned long __user *nmask,
+                                   unsigned long maxnode)
+{
+        int err;
+        struct mempolicy *new;
+        DECLARE_BITMAP(nodes, MAX_NUMNODES);
+
+        if (mode > MPOL_MAX)
+                return -EINVAL;
+        err = get_nodes(nodes, nmask, maxnode, mode);
+        if (err)
+                return err;
+        new = mpol_new(mode, nodes);
+        if (IS_ERR(new))
+                return PTR_ERR(new);
+        mpol_free(current->mempolicy);
+        current->mempolicy = new;
+        if (new && new->policy == MPOL_INTERLEAVE)
+                current->il_next = find_first_bit(new->v.nodes, MAX_NUMNODES);
+        return 0;
+}
+
+/* Fill a zone bitmap for a policy */
+static void get_zonemask(struct mempolicy *p, unsigned long *nodes)
+{
+        int i;
+
+        bitmap_zero(nodes, MAX_NUMNODES);
+        switch (p->policy) {
+        case MPOL_BIND:
+                for (i = 0; p->v.zonelist->zones[i]; i++)
+                        __set_bit(p->v.zonelist->zones[i]->zone_pgdat->node_id, nodes);
+                break;
+        case MPOL_DEFAULT:
+                break;
+        case MPOL_INTERLEAVE:
+                bitmap_copy(nodes, p->v.nodes, MAX_NUMNODES);
+                break;
+        case MPOL_PREFERRED:
+                /* or use current node instead of online map? */
+                if (p->v.preferred_node < 0)
+                        bitmap_copy(nodes, nodes_addr(node_online_map), MAX_NUMNODES);
+                else
+                        __set_bit(p->v.preferred_node, nodes);
+                break;
+        default:
+                BUG();
+        }
+}
+
+static int lookup_node(struct mm_struct *mm, unsigned long addr)
+{
+        struct page *p;
+        int err;
+
+        err = get_user_pages(current, mm, addr & PAGE_MASK, 1, 0, 0, &p, NULL);
+        if (err >= 0) {
+                err = page_to_nid(p);
+                put_page(p);
+        }
+        return err;
+}
+
+/* Copy a kernel node mask to user space */
+static int copy_nodes_to_user(unsigned long __user *mask, unsigned long maxnode,
+                              void *nodes, unsigned nbytes)
+{
+        unsigned long copy = ALIGN(maxnode-1, 64) / 8;
+
+        if (copy > nbytes) {
+                if (copy > PAGE_SIZE)
+                        return -EINVAL;
+                if (clear_user((char __user *)mask + nbytes, copy - nbytes))
+                        return -EFAULT;
+                copy = nbytes;
+        }
+        return copy_to_user(mask, nodes, copy) ? -EFAULT : 0;
+}
+
+/* Retrieve NUMA policy */
+asmlinkage long sys_get_mempolicy(int __user *policy,
+                                  unsigned long __user *nmask,
+                                  unsigned long maxnode,
+                                  unsigned long addr, unsigned long flags)
+{
+        int err, pval;
+        struct mm_struct *mm = current->mm;
+        struct vm_area_struct *vma = NULL;
+        struct mempolicy *pol = current->mempolicy;
+
+        if (flags & ~(unsigned long)(MPOL_F_NODE|MPOL_F_ADDR))
+                return -EINVAL;
+        if (nmask != NULL && maxnode < MAX_NUMNODES)
+                return -EINVAL;
+        if (flags & MPOL_F_ADDR) {
+                down_read(&mm->mmap_sem);
+                vma = find_vma_intersection(mm, addr, addr+1);
+                if (!vma) {
+                        up_read(&mm->mmap_sem);
+                        return -EFAULT;
+                }
+                if (vma->vm_ops && vma->vm_ops->get_policy)
+                        pol = vma->vm_ops->get_policy(vma, addr);
+                else
+                        pol = vma->vm_policy;
+        } else if (addr)
+                return -EINVAL;
+
+        if (!pol)
+                pol = &default_policy;
+
+        if (flags & MPOL_F_NODE) {
+                if (flags & MPOL_F_ADDR) {
+                        err = lookup_node(mm, addr);
+                        if (err < 0)
+                                goto out;
+                        pval = err;
+                } else if (pol == current->mempolicy &&
+                                pol->policy == MPOL_INTERLEAVE) {
+                        pval = current->il_next;
+                } else {
+                        err = -EINVAL;
+                        goto out;
+                }
+        } else
+                pval = pol->policy;
+
+        if (vma) {
+                up_read(&current->mm->mmap_sem);
+                vma = NULL;
+        }
+
+        if (policy && put_user(pval, policy))
+                return -EFAULT;
+
+        err = 0;
+        if (nmask) {
+                DECLARE_BITMAP(nodes, MAX_NUMNODES);
+                get_zonemask(pol, nodes);
+                err = copy_nodes_to_user(nmask, maxnode, nodes, sizeof(nodes));
+        }
+
+ out:
+        if (vma)
+                up_read(&current->mm->mmap_sem);
+        return err;
+}
+
+#ifdef CONFIG_COMPAT
+
+asmlinkage long compat_sys_get_mempolicy(int __user *policy,
+                                     compat_ulong_t __user *nmask,
+                                     compat_ulong_t maxnode,
+                                     compat_ulong_t addr, compat_ulong_t flags)
+{
+        long err;
+        unsigned long __user *nm = NULL;
+        unsigned long nr_bits, alloc_size;
+        DECLARE_BITMAP(bm, MAX_NUMNODES);
+
+        nr_bits = min_t(unsigned long, maxnode-1, MAX_NUMNODES);
+        alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
+
+        if (nmask)
+                nm = compat_alloc_user_space(alloc_size);
+
+        err = sys_get_mempolicy(policy, nm, nr_bits+1, addr, flags);
+
+        if (!err && nmask) {
+                err = copy_from_user(bm, nm, alloc_size);
+                /* ensure entire bitmap is zeroed */
+                err |= clear_user(nmask, ALIGN(maxnode-1, 8) / 8);
+                err |= compat_put_bitmap(nmask, bm, nr_bits);
+        }
+
+        return err;
+}
+
+asmlinkage long compat_sys_set_mempolicy(int mode, compat_ulong_t __user *nmask,
+                                     compat_ulong_t maxnode)
+{
+        long err = 0;
+        unsigned long __user *nm = NULL;
+        unsigned long nr_bits, alloc_size;
+        DECLARE_BITMAP(bm, MAX_NUMNODES);
+
+        nr_bits = min_t(unsigned long, maxnode-1, MAX_NUMNODES);
+        alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
+
+        if (nmask) {
+                err = compat_get_bitmap(bm, nmask, nr_bits);
+                nm = compat_alloc_user_space(alloc_size);
+                err |= copy_to_user(nm, bm, alloc_size);
+        }
+
+        if (err)
+                return -EFAULT;
+
+        return sys_set_mempolicy(mode, nm, nr_bits+1);
+}
+
+asmlinkage long compat_sys_mbind(compat_ulong_t start, compat_ulong_t len,
+                             compat_ulong_t mode, compat_ulong_t __user *nmask,
+                             compat_ulong_t maxnode, compat_ulong_t flags)
+{
+        long err = 0;
+        unsigned long __user *nm = NULL;
+        unsigned long nr_bits, alloc_size;
+        DECLARE_BITMAP(bm, MAX_NUMNODES);
+
+        nr_bits = min_t(unsigned long, maxnode-1, MAX_NUMNODES);
+        alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
+
+        if (nmask) {
+                err = compat_get_bitmap(bm, nmask, nr_bits);
+                nm = compat_alloc_user_space(alloc_size);
+                err |= copy_to_user(nm, bm, alloc_size);
+        }
+
+        if (err)
+                return -EFAULT;
+
+        return sys_mbind(start, len, mode, nm, nr_bits+1, flags);
+}
+
+#endif
+
+/* Return effective policy for a VMA */
+static struct mempolicy *
+get_vma_policy(struct vm_area_struct *vma, unsigned long addr)
+{
+        struct mempolicy *pol = current->mempolicy;
+
+        if (vma) {
+                if (vma->vm_ops && vma->vm_ops->get_policy)
+                        pol = vma->vm_ops->get_policy(vma, addr);
+                else if (vma->vm_policy &&
+                                vma->vm_policy->policy != MPOL_DEFAULT)
+                        pol = vma->vm_policy;
+        }
+        if (!pol)
+                pol = &default_policy;
+        return pol;
+}
+
+/* Return a zonelist representing a mempolicy */
+static struct zonelist *zonelist_policy(unsigned int __nocast gfp, struct mempolicy *policy)
+{
+        int nd;
+
+        switch (policy->policy) {
+        case MPOL_PREFERRED:
+                nd = policy->v.preferred_node;
+                if (nd < 0)
+                        nd = numa_node_id();
+                break;
+        case MPOL_BIND:
+                /* Lower zones don't get a policy applied */
+                /* Careful: current->mems_allowed might have moved */
+                if (gfp >= policy_zone)
+                        if (cpuset_zonelist_valid_mems_allowed(policy->v.zonelist))
+                                return policy->v.zonelist;
+                /*FALL THROUGH*/
+        case MPOL_INTERLEAVE: /* should not happen */
+        case MPOL_DEFAULT:
+                nd = numa_node_id();
+                break;
+        default:
+                nd = 0;
+                BUG();
+        }
+        return NODE_DATA(nd)->node_zonelists + (gfp & GFP_ZONEMASK);
+}
+
+/* Do dynamic interleaving for a process */
+static unsigned interleave_nodes(struct mempolicy *policy)
+{
+        unsigned nid, next;
+        struct task_struct *me = current;
+
+        nid = me->il_next;
+        BUG_ON(nid >= MAX_NUMNODES);
+        next = find_next_bit(policy->v.nodes, MAX_NUMNODES, 1+nid);
+        if (next >= MAX_NUMNODES)
+                next = find_first_bit(policy->v.nodes, MAX_NUMNODES);
+        me->il_next = next;
+        return nid;
+}
+
+/* Do static interleaving for a VMA with known offset. */
+static unsigned offset_il_node(struct mempolicy *pol,
+                struct vm_area_struct *vma, unsigned long off)
+{
+        unsigned nnodes = bitmap_weight(pol->v.nodes, MAX_NUMNODES);
+        unsigned target = (unsigned)off % nnodes;
+        int c;
+        int nid = -1;
+
+        c = 0;
+        do {
+                nid = find_next_bit(pol->v.nodes, MAX_NUMNODES, nid+1);
+                c++;
+        } while (c <= target);
+        BUG_ON(nid >= MAX_NUMNODES);
+        BUG_ON(!test_bit(nid, pol->v.nodes));
+        return nid;
+}
+
+/* Allocate a page in interleaved policy.
+   Own path because it needs to do special accounting. */
+static struct page *alloc_page_interleave(unsigned int __nocast gfp, unsigned order, unsigned nid)
+{
+        struct zonelist *zl;
+        struct page *page;
+
+        BUG_ON(!node_online(nid));
+        zl = NODE_DATA(nid)->node_zonelists + (gfp & GFP_ZONEMASK);
+        page = __alloc_pages(gfp, order, zl);
+        if (page && page_zone(page) == zl->zones[0]) {
+                zl->zones[0]->pageset[get_cpu()].interleave_hit++;
+                put_cpu();
+        }
+        return page;
+}
+
+/**
+ *      alloc_page_vma  - Allocate a page for a VMA.
+ *
+ *      @gfp:
+ *      %GFP_USER    user allocation.
+ *      %GFP_KERNEL  kernel allocations,
+ *      %GFP_HIGHMEM highmem/user allocations,
+ *      %GFP_FS      allocation should not call back into a file system.
+ *      %GFP_ATOMIC  don't sleep.
+ *
+ *      @vma:  Pointer to VMA or NULL if not available.
+ *      @addr: Virtual Address of the allocation. Must be inside the VMA.
+ *
+ *      This function allocates a page from the kernel page pool and applies
+ *      a NUMA policy associated with the VMA or the current process.
+ *      When VMA is not NULL caller must hold down_read on the mmap_sem of the
+ *      mm_struct of the VMA to prevent it from going away. Should be used for
+ *      all allocations for pages that will be mapped into
+ *      user space. Returns NULL when no page can be allocated.
+ *
+ *      Should be called with the mm_sem of the vma hold.
+ */
+struct page *
+alloc_page_vma(unsigned int __nocast gfp, struct vm_area_struct *vma, unsigned long addr)
+{
+        struct mempolicy *pol = get_vma_policy(vma, addr);
+
+        cpuset_update_current_mems_allowed();
+
+        if (unlikely(pol->policy == MPOL_INTERLEAVE)) {
+                unsigned nid;
+                if (vma) {
+                        unsigned long off;
+                        BUG_ON(addr >= vma->vm_end);
+                        BUG_ON(addr < vma->vm_start);
+                        off = vma->vm_pgoff;
+                        off += (addr - vma->vm_start) >> PAGE_SHIFT;
+                        nid = offset_il_node(pol, vma, off);
+                } else {
+                        /* fall back to process interleaving */
+                        nid = interleave_nodes(pol);
+                }
+                return alloc_page_interleave(gfp, 0, nid);
+        }
+        return __alloc_pages(gfp, 0, zonelist_policy(gfp, pol));
+}
+
+/**
+ *      alloc_pages_current - Allocate pages.
+ *
+ *      @gfp:
+ *              %GFP_USER   user allocation,
+ *              %GFP_KERNEL kernel allocation,
+ *              %GFP_HIGHMEM highmem allocation,
+ *              %GFP_FS     don't call back into a file system.
+ *              %GFP_ATOMIC don't sleep.
+ *      @order: Power of two of allocation size in pages. 0 is a single page.
+ *
+ *      Allocate a page from the kernel page pool.  When not in
+ *      interrupt context and apply the current process NUMA policy.
+ *      Returns NULL when no page can be allocated.
+ *
+ *      Don't call cpuset_update_current_mems_allowed() unless
+ *      1) it's ok to take cpuset_sem (can WAIT), and
+ *      2) allocating for current task (not interrupt).
+ */
+struct page *alloc_pages_current(unsigned int __nocast gfp, unsigned order)
+{
+        struct mempolicy *pol = current->mempolicy;
+
+        if ((gfp & __GFP_WAIT) && !in_interrupt())
+                cpuset_update_current_mems_allowed();
+        if (!pol || in_interrupt())
+                pol = &default_policy;
+        if (pol->policy == MPOL_INTERLEAVE)
+                return alloc_page_interleave(gfp, order, interleave_nodes(pol));
+        return __alloc_pages(gfp, order, zonelist_policy(gfp, pol));
+}
+EXPORT_SYMBOL(alloc_pages_current);
+
+/* Slow path of a mempolicy copy */
+struct mempolicy *__mpol_copy(struct mempolicy *old)
+{
+        struct mempolicy *new = kmem_cache_alloc(policy_cache, GFP_KERNEL);
+
+        if (!new)
+                return ERR_PTR(-ENOMEM);
+        *new = *old;
+        atomic_set(&new->refcnt, 1);
+        if (new->policy == MPOL_BIND) {
+                int sz = ksize(old->v.zonelist);
+                new->v.zonelist = kmalloc(sz, SLAB_KERNEL);
+                if (!new->v.zonelist) {
+                        kmem_cache_free(policy_cache, new);
+                        return ERR_PTR(-ENOMEM);
+                }
+                memcpy(new->v.zonelist, old->v.zonelist, sz);
+        }
+        return new;
+}
+
+/* Slow path of a mempolicy comparison */
+int __mpol_equal(struct mempolicy *a, struct mempolicy *b)
+{
+        if (!a || !b)
+                return 0;
+        if (a->policy != b->policy)
+                return 0;
+        switch (a->policy) {
+        case MPOL_DEFAULT:
+                return 1;
+        case MPOL_INTERLEAVE:
+                return bitmap_equal(a->v.nodes, b->v.nodes, MAX_NUMNODES);
+        case MPOL_PREFERRED:
+                return a->v.preferred_node == b->v.preferred_node;
+        case MPOL_BIND: {
+                int i;
+                for (i = 0; a->v.zonelist->zones[i]; i++)
+                        if (a->v.zonelist->zones[i] != b->v.zonelist->zones[i])
+                                return 0;
+                return b->v.zonelist->zones[i] == NULL;
+        }
+        default:
+                BUG();
+                return 0;
+        }
+}
+
+/* Slow path of a mpol destructor. */
+void __mpol_free(struct mempolicy *p)
+{
+        if (!atomic_dec_and_test(&p->refcnt))
+                return;
+        if (p->policy == MPOL_BIND)
+                kfree(p->v.zonelist);
+        p->policy = MPOL_DEFAULT;
+        kmem_cache_free(policy_cache, p);
+}
+
+/*
+ * Hugetlb policy. Same as above, just works with node numbers instead of
+ * zonelists.
+ */
+
+/* Find first node suitable for an allocation */
+int mpol_first_node(struct vm_area_struct *vma, unsigned long addr)
+{
+        struct mempolicy *pol = get_vma_policy(vma, addr);
+
+        switch (pol->policy) {
+        case MPOL_DEFAULT:
+                return numa_node_id();
+        case MPOL_BIND:
+                return pol->v.zonelist->zones[0]->zone_pgdat->node_id;
+        case MPOL_INTERLEAVE:
+                return interleave_nodes(pol);
+        case MPOL_PREFERRED:
+                return pol->v.preferred_node >= 0 ?
+                                pol->v.preferred_node : numa_node_id();
+        }
+        BUG();
+        return 0;
+}
+
+/* Find secondary valid nodes for an allocation */
+int mpol_node_valid(int nid, struct vm_area_struct *vma, unsigned long addr)
+{
+        struct mempolicy *pol = get_vma_policy(vma, addr);
+
+        switch (pol->policy) {
+        case MPOL_PREFERRED:
+        case MPOL_DEFAULT:
+        case MPOL_INTERLEAVE:
+                return 1;
+        case MPOL_BIND: {
+                struct zone **z;
+                for (z = pol->v.zonelist->zones; *z; z++)
+                        if ((*z)->zone_pgdat->node_id == nid)
+                                return 1;
+                return 0;
+        }
+        default:
+                BUG();
+                return 0;
+        }
+}
+
+/*
+ * Shared memory backing store policy support.
+ *
+ * Remember policies even when nobody has shared memory mapped.
+ * The policies are kept in Red-Black tree linked from the inode.
+ * They are protected by the sp->lock spinlock, which should be held
+ * for any accesses to the tree.
+ */
+
+/* lookup first element intersecting start-end */
+/* Caller holds sp->lock */
+static struct sp_node *
+sp_lookup(struct shared_policy *sp, unsigned long start, unsigned long end)
+{
+        struct rb_node *n = sp->root.rb_node;
+
+        while (n) {
+                struct sp_node *p = rb_entry(n, struct sp_node, nd);
+
+                if (start >= p->end)
+                        n = n->rb_right;
+                else if (end <= p->start)
+                        n = n->rb_left;
+                else
+                        break;
+        }
+        if (!n)
+                return NULL;
+        for (;;) {
+                struct sp_node *w = NULL;
+                struct rb_node *prev = rb_prev(n);
+                if (!prev)
+                        break;
+                w = rb_entry(prev, struct sp_node, nd);
+                if (w->end <= start)
+                        break;
+                n = prev;
+        }
+        return rb_entry(n, struct sp_node, nd);
+}
+
+/* Insert a new shared policy into the list. */
+/* Caller holds sp->lock */
+static void sp_insert(struct shared_policy *sp, struct sp_node *new)
+{
+        struct rb_node **p = &sp->root.rb_node;
+        struct rb_node *parent = NULL;
+        struct sp_node *nd;
+
+        while (*p) {
+                parent = *p;
+                nd = rb_entry(parent, struct sp_node, nd);
+                if (new->start < nd->start)
+                        p = &(*p)->rb_left;
+                else if (new->end > nd->end)
+                        p = &(*p)->rb_right;
+                else
+                        BUG();
+        }
+        rb_link_node(&new->nd, parent, p);
+        rb_insert_color(&new->nd, &sp->root);
+        PDprintk("inserting %lx-%lx: %d\n", new->start, new->end,
+                 new->policy ? new->policy->policy : 0);
+}
+
+/* Find shared policy intersecting idx */
+struct mempolicy *
+mpol_shared_policy_lookup(struct shared_policy *sp, unsigned long idx)
+{
+        struct mempolicy *pol = NULL;
+        struct sp_node *sn;
+
+        if (!sp->root.rb_node)
+                return NULL;
+        spin_lock(&sp->lock);
+        sn = sp_lookup(sp, idx, idx+1);
+        if (sn) {
+                mpol_get(sn->policy);
+                pol = sn->policy;
+        }
+        spin_unlock(&sp->lock);
+        return pol;
+}
+
+static void sp_delete(struct shared_policy *sp, struct sp_node *n)
+{
+        PDprintk("deleting %lx-l%x\n", n->start, n->end);
+        rb_erase(&n->nd, &sp->root);
+        mpol_free(n->policy);
+        kmem_cache_free(sn_cache, n);
+}
+
+struct sp_node *
+sp_alloc(unsigned long start, unsigned long end, struct mempolicy *pol)
+{
+        struct sp_node *n = kmem_cache_alloc(sn_cache, GFP_KERNEL);
+
+        if (!n)
+                return NULL;
+        n->start = start;
+        n->end = end;
+        mpol_get(pol);
+        n->policy = pol;
+        return n;
+}
+
+/* Replace a policy range. */
+static int shared_policy_replace(struct shared_policy *sp, unsigned long start,
+                                 unsigned long end, struct sp_node *new)
+{
+        struct sp_node *n, *new2 = NULL;
+
+restart:
+        spin_lock(&sp->lock);
+        n = sp_lookup(sp, start, end);
+        /* Take care of old policies in the same range. */
+        while (n && n->start < end) {
+                struct rb_node *next = rb_next(&n->nd);
+                if (n->start >= start) {
+                        if (n->end <= end)
+                                sp_delete(sp, n);
+                        else
+                                n->start = end;
+                } else {
+                        /* Old policy spanning whole new range. */
+                        if (n->end > end) {
+                                if (!new2) {
+                                        spin_unlock(&sp->lock);
+                                        new2 = sp_alloc(end, n->end, n->policy);
+                                        if (!new2)
+                                                return -ENOMEM;
+                                        goto restart;
+                                }
+                                n->end = start;
+                                sp_insert(sp, new2);
+                                new2 = NULL;
+                                break;
+                        } else
+                                n->end = start;
+                }
+                if (!next)
+                        break;
+                n = rb_entry(next, struct sp_node, nd);
+        }
+        if (new)
+                sp_insert(sp, new);
+        spin_unlock(&sp->lock);
+        if (new2) {
+                mpol_free(new2->policy);
+                kmem_cache_free(sn_cache, new2);
+        }
+        return 0;
+}
+
+int mpol_set_shared_policy(struct shared_policy *info,
+                        struct vm_area_struct *vma, struct mempolicy *npol)
+{
+        int err;
+        struct sp_node *new = NULL;
+        unsigned long sz = vma_pages(vma);
+
+        PDprintk("set_shared_policy %lx sz %lu %d %lx\n",
+                 vma->vm_pgoff,
+                 sz, npol? npol->policy : -1,
+                npol ? npol->v.nodes[0] : -1);
+
+        if (npol) {
+                new = sp_alloc(vma->vm_pgoff, vma->vm_pgoff + sz, npol);
+                if (!new)
+                        return -ENOMEM;
+        }
+        err = shared_policy_replace(info, vma->vm_pgoff, vma->vm_pgoff+sz, new);
+        if (err && new)
+                kmem_cache_free(sn_cache, new);
+        return err;
+}
+
+/* Free a backing policy store on inode delete. */
+void mpol_free_shared_policy(struct shared_policy *p)
+{
+        struct sp_node *n;
+        struct rb_node *next;
+
+        if (!p->root.rb_node)
+                return;
+        spin_lock(&p->lock);
+        next = rb_first(&p->root);
+        while (next) {
+                n = rb_entry(next, struct sp_node, nd);
+                next = rb_next(&n->nd);
+                mpol_free(n->policy);
+                kmem_cache_free(sn_cache, n);
+        }
+        spin_unlock(&p->lock);
+        p->root = RB_ROOT;
+}
+
+/* assumes fs == KERNEL_DS */
+void __init numa_policy_init(void)
+{
+        policy_cache = kmem_cache_create("numa_policy",
+                                         sizeof(struct mempolicy),
+                                         0, SLAB_PANIC, NULL, NULL);
+
+        sn_cache = kmem_cache_create("shared_policy_node",
+                                     sizeof(struct sp_node),
+                                     0, SLAB_PANIC, NULL, NULL);
+
+        /* Set interleaving policy for system init. This way not all
+           the data structures allocated at system boot end up in node zero. */
+
+        if (sys_set_mempolicy(MPOL_INTERLEAVE, nodes_addr(node_online_map),
+                                                        MAX_NUMNODES) < 0)
+                printk("numa_policy_init: interleaving failed\n");
+}
+
+/* Reset policy of current process to default.
+ * Assumes fs == KERNEL_DS */
+void numa_default_policy(void)
+{
+        sys_set_mempolicy(MPOL_DEFAULT, NULL, 0);
+}