1 files changed, 103 insertions, 40 deletions

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 3eb4a6fdc043..46bdf9ddf2ba 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -182,13 +182,54 @@ static int mpol_new_bind(struct mempolicy *pol, const nodemask_t *nodes)
         return 0;
 }
 
-/* Create a new policy */
+/*
+ * mpol_set_nodemask is called after mpol_new() to set up the nodemask, if
+ * any, for the new policy.  mpol_new() has already validated the nodes
+ * parameter with respect to the policy mode and flags.  But, we need to
+ * handle an empty nodemask with MPOL_PREFERRED here.
+ *
+ * Must be called holding task's alloc_lock to protect task's mems_allowed
+ * and mempolicy.  May also be called holding the mmap_semaphore for write.
+ */
+static int mpol_set_nodemask(struct mempolicy *pol, const nodemask_t *nodes)
+{
+        nodemask_t cpuset_context_nmask;
+        int ret;
+
+        /* if mode is MPOL_DEFAULT, pol is NULL. This is right. */
+        if (pol == NULL)
+                return 0;
+
+        VM_BUG_ON(!nodes);
+        if (pol->mode == MPOL_PREFERRED && nodes_empty(*nodes))
+                nodes = NULL;   /* explicit local allocation */
+        else {
+                if (pol->flags & MPOL_F_RELATIVE_NODES)
+                        mpol_relative_nodemask(&cpuset_context_nmask, nodes,
+                                               &cpuset_current_mems_allowed);
+                else
+                        nodes_and(cpuset_context_nmask, *nodes,
+                                  cpuset_current_mems_allowed);
+                if (mpol_store_user_nodemask(pol))
+                        pol->w.user_nodemask = *nodes;
+                else
+                        pol->w.cpuset_mems_allowed =
+                                                cpuset_current_mems_allowed;
+        }
+
+        ret = mpol_ops[pol->mode].create(pol,
+                                nodes ? &cpuset_context_nmask : NULL);
+        return ret;
+}
+
+/*
+ * This function just creates a new policy, does some check and simple
+ * initialization. You must invoke mpol_set_nodemask() to set nodes.
+ */
 static struct mempolicy *mpol_new(unsigned short mode, unsigned short flags,
                                   nodemask_t *nodes)
 {
         struct mempolicy *policy;
-        nodemask_t cpuset_context_nmask;
-        int ret;
 
         pr_debug("setting mode %d flags %d nodes[0] %lx\n",
                  mode, flags, nodes ? nodes_addr(*nodes)[0] : -1);
@@ -210,7 +251,6 @@ static struct mempolicy *mpol_new(unsigned short mode, unsigned short flags,
                         if (((flags & MPOL_F_STATIC_NODES) ||
                              (flags & MPOL_F_RELATIVE_NODES)))
                                 return ERR_PTR(-EINVAL);
-                        nodes = NULL;   /* flag local alloc */
                 }
         } else if (nodes_empty(*nodes))
                 return ERR_PTR(-EINVAL);
@@ -221,30 +261,6 @@ static struct mempolicy *mpol_new(unsigned short mode, unsigned short flags,
         policy->mode = mode;
         policy->flags = flags;
 
-        if (nodes) {
-                /*
-                 * cpuset related setup doesn't apply to local allocation
-                 */
-                cpuset_update_task_memory_state();
-                if (flags & MPOL_F_RELATIVE_NODES)
-                        mpol_relative_nodemask(&cpuset_context_nmask, nodes,
-                                               &cpuset_current_mems_allowed);
-                else
-                        nodes_and(cpuset_context_nmask, *nodes,
-                                  cpuset_current_mems_allowed);
-                if (mpol_store_user_nodemask(policy))
-                        policy->w.user_nodemask = *nodes;
-                else
-                        policy->w.cpuset_mems_allowed =
-                                                cpuset_mems_allowed(current);
-        }
-
-        ret = mpol_ops[mode].create(policy,
-                                nodes ? &cpuset_context_nmask : NULL);
-        if (ret < 0) {
-                kmem_cache_free(policy_cache, policy);
-                return ERR_PTR(ret);
-        }
         return policy;
 }
 
@@ -324,6 +340,8 @@ static void mpol_rebind_policy(struct mempolicy *pol,
 /*
  * Wrapper for mpol_rebind_policy() that just requires task
  * pointer, and updates task mempolicy.
+ *
+ * Called with task's alloc_lock held.
  */
 
 void mpol_rebind_task(struct task_struct *tsk, const nodemask_t *new)
@@ -600,8 +618,9 @@ static void mpol_set_task_struct_flag(void)
 static long do_set_mempolicy(unsigned short mode, unsigned short flags,
                              nodemask_t *nodes)
 {
-        struct mempolicy *new;
+        struct mempolicy *new, *old;
         struct mm_struct *mm = current->mm;
+        int ret;
 
         new = mpol_new(mode, flags, nodes);
         if (IS_ERR(new))
@@ -615,20 +634,33 @@ static long do_set_mempolicy(unsigned short mode, unsigned short flags,
          */
         if (mm)
                 down_write(&mm->mmap_sem);
-        mpol_put(current->mempolicy);
+        task_lock(current);
+        ret = mpol_set_nodemask(new, nodes);
+        if (ret) {
+                task_unlock(current);
+                if (mm)
+                        up_write(&mm->mmap_sem);
+                mpol_put(new);
+                return ret;
+        }
+        old = current->mempolicy;
         current->mempolicy = new;
         mpol_set_task_struct_flag();
         if (new && new->mode == MPOL_INTERLEAVE &&
             nodes_weight(new->v.nodes))
                 current->il_next = first_node(new->v.nodes);
+        task_unlock(current);
         if (mm)
                 up_write(&mm->mmap_sem);
 
+        mpol_put(old);
         return 0;
 }
 
 /*
  * Return nodemask for policy for get_mempolicy() query
+ *
+ * Called with task's alloc_lock held
  */
 static void get_policy_nodemask(struct mempolicy *p, nodemask_t *nodes)
 {
@@ -674,7 +706,6 @@ static long do_get_mempolicy(int *policy, nodemask_t *nmask,
         struct vm_area_struct *vma = NULL;
         struct mempolicy *pol = current->mempolicy;
 
-        cpuset_update_task_memory_state();
         if (flags &
                 ~(unsigned long)(MPOL_F_NODE|MPOL_F_ADDR|MPOL_F_MEMS_ALLOWED))
                 return -EINVAL;
@@ -683,7 +714,9 @@ static long do_get_mempolicy(int *policy, nodemask_t *nmask,
                 if (flags & (MPOL_F_NODE|MPOL_F_ADDR))
                         return -EINVAL;
                 *policy = 0;    /* just so it's initialized */
+                task_lock(current);
                 *nmask  = cpuset_current_mems_allowed;
+                task_unlock(current);
                 return 0;
         }
 
@@ -738,8 +771,11 @@ static long do_get_mempolicy(int *policy, nodemask_t *nmask,
         }
 
         err = 0;
-        if (nmask)
+        if (nmask) {
+                task_lock(current);
                 get_policy_nodemask(pol, nmask);
+                task_unlock(current);
+        }
 
  out:
         mpol_cond_put(pol);
@@ -979,6 +1015,14 @@ static long do_mbind(unsigned long start, unsigned long len,
                         return err;
         }
         down_write(&mm->mmap_sem);
+        task_lock(current);
+        err = mpol_set_nodemask(new, nmask);
+        task_unlock(current);
+        if (err) {
+                up_write(&mm->mmap_sem);
+                mpol_put(new);
+                return err;
+        }
         vma = check_range(mm, start, end, nmask,
                           flags | MPOL_MF_INVERT, &pagelist);
 
@@ -1545,8 +1589,6 @@ alloc_page_vma(gfp_t gfp, struct vm_area_struct *vma, unsigned long addr)
         struct mempolicy *pol = get_vma_policy(current, vma, addr);
         struct zonelist *zl;
 
-        cpuset_update_task_memory_state();
-
         if (unlikely(pol->mode == MPOL_INTERLEAVE)) {
                 unsigned nid;
 
@@ -1593,8 +1635,6 @@ struct page *alloc_pages_current(gfp_t gfp, unsigned order)
 {
         struct mempolicy *pol = current->mempolicy;
 
-        if ((gfp & __GFP_WAIT) && !in_interrupt())
-                cpuset_update_task_memory_state();
         if (!pol || in_interrupt() || (gfp & __GFP_THISNODE))
                 pol = &default_policy;
 
@@ -1854,6 +1894,8 @@ restart:
  */
 void mpol_shared_policy_init(struct shared_policy *sp, struct mempolicy *mpol)
 {
+        int ret;
+
         sp->root = RB_ROOT;             /* empty tree == default mempolicy */
         spin_lock_init(&sp->lock);
 
@@ -1863,9 +1905,19 @@ void mpol_shared_policy_init(struct shared_policy *sp, struct mempolicy *mpol)
 
                 /* contextualize the tmpfs mount point mempolicy */
                 new = mpol_new(mpol->mode, mpol->flags, &mpol->w.user_nodemask);
-                mpol_put(mpol); /* drop our ref on sb mpol */
-                if (IS_ERR(new))
+                if (IS_ERR(new)) {
+                        mpol_put(mpol); /* drop our ref on sb mpol */
                         return;         /* no valid nodemask intersection */
+                }
+
+                task_lock(current);
+                ret = mpol_set_nodemask(new, &mpol->w.user_nodemask);
+                task_unlock(current);
+                mpol_put(mpol); /* drop our ref on sb mpol */
+                if (ret) {
+                        mpol_put(new);
+                        return;
+                }
 
                 /* Create pseudo-vma that contains just the policy */
                 memset(&pvma, 0, sizeof(struct vm_area_struct));
@@ -2086,8 +2138,19 @@ int mpol_parse_str(char *str, struct mempolicy **mpol, int no_context)
         new = mpol_new(mode, mode_flags, &nodes);
         if (IS_ERR(new))
                 err = 1;
-        else if (no_context)
-                new->w.user_nodemask = nodes;   /* save for contextualization */
+        else {
+                int ret;
+
+                task_lock(current);
+                ret = mpol_set_nodemask(new, &nodes);
+                task_unlock(current);
+                if (ret)
+                        err = 1;
+                else if (no_context) {
+                        /* save for contextualization */
+                        new->w.user_nodemask = nodes;
+                }
+        }
 
 out:
         /* Restore string for error message */