Commit message: mm: mempolicy: require at least one nodeid for MPOL_PREFERRED

Using an empty (malformed) nodelist that is not caught during mount option
parsing leads to a stack-out-of-bounds access.

The option string that was used was: "mpol=prefer:,".  However,
MPOL_PREFERRED requires a single node number, which is not being provided
here.

Add a check that 'nodes' is not empty after parsing for MPOL_PREFERRED's
nodeid.

Fixes: 095f1fc4ebf3 ("mempolicy: rework shmem mpol parsing and display")
Reported-by: Entropy Moe <3ntr0py1337@gmail.com>
Reported-by: syzbot+b055b1a6b2b958707a21@syzkaller.appspotmail.com
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: syzbot+b055b1a6b2b958707a21@syzkaller.appspotmail.com
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Link: http://lkml.kernel.org/r/89526377-7eb6-b662-e1d8-4430928abde9@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
CVE: CVE-2020-11565
CWE: CWE-787
Vulnerability description: An issue was discovered in the Linux kernel through 5.6.2. mpol_parse_str in mm/mempolicy.c has a stack-based out-of-bounds write because an empty nodelist is mishandled during mount option parsing, aka CID-aa9f7d5172fa. NOTE: Someone in the security community disagrees that this is a vulnerability because the issue “is a bug in parsing mount options which can only be specified by a privileged user, so triggering the bug does not grant any powers not already held.”

Project: linux
File: mempolicy.c

static nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *policy)
{
	/* Lower zones don't get a nodemask applied for MPOL_BIND */
	if (unlikely(policy->mode == MPOL_BIND) &&
			apply_policy_zone(policy, gfp_zone(gfp)) &&
			cpuset_nodemask_valid_mems_allowed(&policy->v.nodes))
		return &policy->v.nodes;

	return NULL;
}

Project: linux
File: mempolicy.c

static int mpol_new_preferred(struct mempolicy *pol, const nodemask_t *nodes)
{
	if (!nodes)
		pol->flags |= MPOL_F_LOCAL;	/* local allocation */
	else if (nodes_empty(*nodes))
		return -EINVAL;			/*  no allowed nodes */
	else
		pol->v.preferred_node = first_node(*nodes);
	return 0;
}

Project: linux
File: mempolicy.c

static int __init setup_numabalancing(char *str)
{
	int ret = 0;
	if (!str)
		goto out;

	if (!strcmp(str, "enable")) {
		numabalancing_override = 1;
		ret = 1;
	} else if (!strcmp(str, "disable")) {
		numabalancing_override = -1;
		ret = 1;
	}
out:
	if (!ret)
		pr_warn("Unable to parse numa_balancing=\n");

	return ret;
}

Project: linux
File: mempolicy.c

static void mpol_rebind_nodemask(struct mempolicy *pol, const nodemask_t *nodes)
{
	nodemask_t tmp;

	if (pol->flags & MPOL_F_STATIC_NODES)
		nodes_and(tmp, pol->w.user_nodemask, *nodes);
	else if (pol->flags & MPOL_F_RELATIVE_NODES)
		mpol_relative_nodemask(&tmp, &pol->w.user_nodemask, nodes);
	else {
		nodes_remap(tmp, pol->v.nodes,pol->w.cpuset_mems_allowed,
								*nodes);
		pol->w.cpuset_mems_allowed = *nodes;
	}

	if (nodes_empty(tmp))
		tmp = *nodes;

	pol->v.nodes = tmp;
}

Project: linux
File: mempolicy.c

static inline int mpol_store_user_nodemask(const struct mempolicy *pol)
{
	return pol->flags & MPOL_MODE_FLAGS;
}

Project: linux
File: mempolicy.c

void numa_default_policy(void)
{
	do_set_mempolicy(MPOL_DEFAULT, 0, NULL);
}

Project: linux
File: mempolicy.c

static int shared_policy_replace(struct shared_policy *sp, unsigned long start,
				 unsigned long end, struct sp_node *new)
{
	struct sp_node *n;
	struct sp_node *n_new = NULL;
	struct mempolicy *mpol_new = NULL;
	int ret = 0;

restart:
	write_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 (!n_new)
					goto alloc_new;

				*mpol_new = *n->policy;
				atomic_set(&mpol_new->refcnt, 1);
				sp_node_init(n_new, end, n->end, mpol_new);
				n->end = start;
				sp_insert(sp, n_new);
				n_new = NULL;
				mpol_new = NULL;
				break;
			} else
				n->end = start;
		}
		if (!next)
			break;
		n = rb_entry(next, struct sp_node, nd);
	}
	if (new)
		sp_insert(sp, new);
	write_unlock(&sp->lock);
	ret = 0;

err_out:
	if (mpol_new)
		mpol_put(mpol_new);
	if (n_new)
		kmem_cache_free(sn_cache, n_new);

	return ret;

alloc_new:
	write_unlock(&sp->lock);
	ret = -ENOMEM;
	n_new = kmem_cache_alloc(sn_cache, GFP_KERNEL);
	if (!n_new)
		goto err_out;
	mpol_new = kmem_cache_alloc(policy_cache, GFP_KERNEL);
	if (!mpol_new)
		goto err_out;
	goto restart;
}

Project: linux
File: mempolicy.c

static long kernel_mbind(unsigned long start, unsigned long len,
			 unsigned long mode, const unsigned long __user *nmask,
			 unsigned long maxnode, unsigned int flags)
{
	nodemask_t nodes;
	int err;
	unsigned short mode_flags;

	start = untagged_addr(start);
	mode_flags = mode & MPOL_MODE_FLAGS;
	mode &= ~MPOL_MODE_FLAGS;
	if (mode >= MPOL_MAX)
		return -EINVAL;
	if ((mode_flags & MPOL_F_STATIC_NODES) &&
	    (mode_flags & MPOL_F_RELATIVE_NODES))
		return -EINVAL;
	err = get_nodes(&nodes, nmask, maxnode);
	if (err)
		return err;
	return do_mbind(start, len, mode, mode_flags, &nodes, flags);
}

Project: linux
File: mempolicy.c

int mpol_misplaced(struct page *page, struct vm_area_struct *vma, unsigned long addr)
{
	struct mempolicy *pol;
	struct zoneref *z;
	int curnid = page_to_nid(page);
	unsigned long pgoff;
	int thiscpu = raw_smp_processor_id();
	int thisnid = cpu_to_node(thiscpu);
	int polnid = NUMA_NO_NODE;
	int ret = -1;

	pol = get_vma_policy(vma, addr);
	if (!(pol->flags & MPOL_F_MOF))
		goto out;

	switch (pol->mode) {
	case MPOL_INTERLEAVE:
		pgoff = vma->vm_pgoff;
		pgoff += (addr - vma->vm_start) >> PAGE_SHIFT;
		polnid = offset_il_node(pol, pgoff);
		break;

	case MPOL_PREFERRED:
		if (pol->flags & MPOL_F_LOCAL)
			polnid = numa_node_id();
		else
			polnid = pol->v.preferred_node;
		break;

	case MPOL_BIND:

		/*
		 * allows binding to multiple nodes.
		 * use current page if in policy nodemask,
		 * else select nearest allowed node, if any.
		 * If no allowed nodes, use current [!misplaced].
		 */
		if (node_isset(curnid, pol->v.nodes))
			goto out;
		z = first_zones_zonelist(
				node_zonelist(numa_node_id(), GFP_HIGHUSER),
				gfp_zone(GFP_HIGHUSER),
				&pol->v.nodes);
		polnid = zone_to_nid(z->zone);
		break;

	default:
		BUG();
	}

	/* Migrate the page towards the node whose CPU is referencing it */
	if (pol->flags & MPOL_F_MORON) {
		polnid = thisnid;

		if (!should_numa_migrate_memory(current, page, curnid, thiscpu))
			goto out;
	}

	if (curnid != polnid)
		ret = polnid;
out:
	mpol_cond_put(pol);

	return ret;
}

Project: linux
File: mempolicy.c

static struct page *new_page(struct page *page, unsigned long start)
{
	return NULL;
}

Project: linux
File: mempolicy.c

static int kernel_get_mempolicy(int __user *policy,
				unsigned long __user *nmask,
				unsigned long maxnode,
				unsigned long addr,
				unsigned long flags)
{
	int err;
	int uninitialized_var(pval);
	nodemask_t nodes;

	addr = untagged_addr(addr);

	if (nmask != NULL && maxnode < nr_node_ids)
		return -EINVAL;

	err = do_get_mempolicy(&pval, &nodes, addr, flags);

	if (err)
		return err;

	if (policy && put_user(pval, policy))
		return -EFAULT;

	if (nmask)
		err = copy_nodes_to_user(nmask, maxnode, &nodes);

	return err;
}

Project: linux
File: mempolicy.c

static int apply_policy_zone(struct mempolicy *policy, enum zone_type zone)
{
	enum zone_type dynamic_policy_zone = policy_zone;

	BUG_ON(dynamic_policy_zone == ZONE_MOVABLE);

	/*
	 * if policy->v.nodes has movable memory only,
	 * we apply policy when gfp_zone(gfp) = ZONE_MOVABLE only.
	 *
	 * policy->v.nodes is intersect with node_states[N_MEMORY].
	 * so if the following test faile, it implies
	 * policy->v.nodes has movable memory only.
	 */
	if (!nodes_intersects(policy->v.nodes, node_states[N_HIGH_MEMORY]))
		dynamic_policy_zone = ZONE_MOVABLE;

	return zone >= dynamic_policy_zone;
}

Project: linux
File: mempolicy.c

static int mpol_set_nodemask(struct mempolicy *pol,
		     const nodemask_t *nodes, struct nodemask_scratch *nsc)
{
	int ret;

	/* if mode is MPOL_DEFAULT, pol is NULL. This is right. */
	if (pol == NULL)
		return 0;
	/* Check N_MEMORY */
	nodes_and(nsc->mask1,
		  cpuset_current_mems_allowed, node_states[N_MEMORY]);

	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(&nsc->mask2, nodes, &nsc->mask1);
		else
			nodes_and(nsc->mask2, *nodes, nsc->mask1);

		if (mpol_store_user_nodemask(pol))
			pol->w.user_nodemask = *nodes;
		else
			pol->w.cpuset_mems_allowed =
						cpuset_current_mems_allowed;
	}

	if (nodes)
		ret = mpol_ops[pol->mode].create(pol, &nsc->mask2);
	else
		ret = mpol_ops[pol->mode].create(pol, NULL);
	return ret;
}

Project: linux
File: mempolicy.c

static int migrate_page_add(struct page *page, struct list_head *pagelist,
				unsigned long flags)
{
	struct page *head = compound_head(page);
	/*
	 * Avoid migrating a page that is shared with others.
	 */
	if ((flags & MPOL_MF_MOVE_ALL) || page_mapcount(head) == 1) {
		if (!isolate_lru_page(head)) {
			list_add_tail(&head->lru, pagelist);
			mod_node_page_state(page_pgdat(head),
				NR_ISOLATED_ANON + page_is_file_cache(head),
				hpage_nr_pages(head));
		} else if (flags & MPOL_MF_STRICT) {
			/*
			 * Non-movable page may reach here.  And, there may be
			 * temporary off LRU pages or non-LRU movable pages.
			 * Treat them as unmovable pages since they can't be
			 * isolated, so they can't be moved at the moment.  It
			 * should return -EIO for this case too.
			 */
			return -EIO;
		}
	}

	return 0;
}

Project: linux
File: mempolicy.c

static int vma_replace_policy(struct vm_area_struct *vma,
						struct mempolicy *pol)
{
	int err;
	struct mempolicy *old;
	struct mempolicy *new;

	pr_debug("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);

	new = mpol_dup(pol);
	if (IS_ERR(new))
		return PTR_ERR(new);

	if (vma->vm_ops && vma->vm_ops->set_policy) {
		err = vma->vm_ops->set_policy(vma, new);
		if (err)
			goto err_out;
	}

	old = vma->vm_policy;
	vma->vm_policy = new; /* protected by mmap_sem */
	mpol_put(old);

	return 0;
 err_out:
	mpol_put(new);
	return err;
}

Project: linux
File: mempolicy.c

queue_pages_range(struct mm_struct *mm, unsigned long start, unsigned long end,
		nodemask_t *nodes, unsigned long flags,
		struct list_head *pagelist)
{
	int err;
	struct queue_pages qp = {
		.pagelist = pagelist,
		.flags = flags,
		.nmask = nodes,
		.start = start,
		.end = end,
		.first = NULL,
	};

	err = walk_page_range(mm, start, end, &queue_pages_walk_ops, &qp);

	if (!qp.first)
		/* whole range in hole */
		err = -EFAULT;

	return err;
}

Project: linux
File: mempolicy.c

static struct mempolicy *mpol_new(unsigned short mode, unsigned short flags,
				  nodemask_t *nodes)
{
	struct mempolicy *policy;

	pr_debug("setting mode %d flags %d nodes[0] %lx\n",
		 mode, flags, nodes ? nodes_addr(*nodes)[0] : NUMA_NO_NODE);

	if (mode == MPOL_DEFAULT) {
		if (nodes && !nodes_empty(*nodes))
			return ERR_PTR(-EINVAL);
		return NULL;
	}
	VM_BUG_ON(!nodes);

	/*
	 * MPOL_PREFERRED cannot be used with MPOL_F_STATIC_NODES or
	 * MPOL_F_RELATIVE_NODES if the nodemask is empty (local allocation).
	 * All other modes require a valid pointer to a non-empty nodemask.
	 */
	if (mode == MPOL_PREFERRED) {
		if (nodes_empty(*nodes)) {
			if (((flags & MPOL_F_STATIC_NODES) ||
			     (flags & MPOL_F_RELATIVE_NODES)))
				return ERR_PTR(-EINVAL);
		}
	} else if (mode == MPOL_LOCAL) {
		if (!nodes_empty(*nodes) ||
		    (flags & MPOL_F_STATIC_NODES) ||
		    (flags & MPOL_F_RELATIVE_NODES))
			return ERR_PTR(-EINVAL);
		mode = MPOL_PREFERRED;
	} else if (nodes_empty(*nodes))
		return ERR_PTR(-EINVAL);
	policy = kmem_cache_alloc(policy_cache, GFP_KERNEL);
	if (!policy)
		return ERR_PTR(-ENOMEM);
	atomic_set(&policy->refcnt, 1);
	policy->mode = mode;
	policy->flags = flags;

	return policy;
}

Project: linux
File: mempolicy.c

struct page *alloc_new_node_page(struct page *page, unsigned long node)
{
	if (PageHuge(page))
		return alloc_huge_page_node(page_hstate(compound_head(page)),
					node);
	else if (PageTransHuge(page)) {
		struct page *thp;

		thp = alloc_pages_node(node,
			(GFP_TRANSHUGE | __GFP_THISNODE),
			HPAGE_PMD_ORDER);
		if (!thp)
			return NULL;
		prep_transhuge_page(thp);
		return thp;
	} else
		return __alloc_pages_node(node, GFP_HIGHUSER_MOVABLE |
						    __GFP_THISNODE, 0);
}

Project: linux
File: mempolicy.c

static int mpol_new_bind(struct mempolicy *pol, const nodemask_t *nodes)
{
	if (nodes_empty(*nodes))
		return -EINVAL;
	pol->v.nodes = *nodes;
	return 0;
}

Project: linux
File: mempolicy.c

static long do_get_mempolicy(int *policy, nodemask_t *nmask,
			     unsigned long addr, unsigned long flags)
{
	int err;
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma = NULL;
	struct mempolicy *pol = current->mempolicy, *pol_refcount = NULL;

	if (flags &
		~(unsigned long)(MPOL_F_NODE|MPOL_F_ADDR|MPOL_F_MEMS_ALLOWED))
		return -EINVAL;

	if (flags & MPOL_F_MEMS_ALLOWED) {
		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;
	}

	if (flags & MPOL_F_ADDR) {
		/*
		 * Do NOT fall back to task policy if the
		 * vma/shared policy at addr is NULL.  We
		 * want to return MPOL_DEFAULT in this case.
		 */
		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;	/* indicates default behavior */

	if (flags & MPOL_F_NODE) {
		if (flags & MPOL_F_ADDR) {
			/*
			 * Take a refcount on the mpol, lookup_node()
			 * wil drop the mmap_sem, so after calling
			 * lookup_node() only "pol" remains valid, "vma"
			 * is stale.
			 */
			pol_refcount = pol;
			vma = NULL;
			mpol_get(pol);
			err = lookup_node(mm, addr);
			if (err < 0)
				goto out;
			*policy = err;
		} else if (pol == current->mempolicy &&
				pol->mode == MPOL_INTERLEAVE) {
			*policy = next_node_in(current->il_prev, pol->v.nodes);
		} else {
			err = -EINVAL;
			goto out;
		}
	} else {
		*policy = pol == &default_policy ? MPOL_DEFAULT :
						pol->mode;
		/*
		 * Internal mempolicy flags must be masked off before exposing
		 * the policy to userspace.
		 */
		*policy |= (pol->flags & MPOL_MODE_FLAGS);
	}

	err = 0;
	if (nmask) {
		if (mpol_store_user_nodemask(pol)) {
			*nmask = pol->w.user_nodemask;
		} else {
			task_lock(current);
			get_policy_nodemask(pol, nmask);
			task_unlock(current);
		}
	}

 out:
	mpol_cond_put(pol);
	if (vma)
		up_read(&mm->mmap_sem);
	if (pol_refcount)
		mpol_put(pol_refcount);
	return err;
}

Project: linux
File: mempolicy.c

int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from,
		     const nodemask_t *to, int flags)
{
	return -ENOSYS;
}

Project: linux
File: mempolicy.c

COMPAT_SYSCALL_DEFINE6(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)
{
	unsigned long __user *nm = NULL;
	unsigned long nr_bits, alloc_size;
	nodemask_t bm;

	nr_bits = min_t(unsigned long, maxnode-1, MAX_NUMNODES);
	alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;

	if (nmask) {
		if (compat_get_bitmap(nodes_addr(bm), nmask, nr_bits))
			return -EFAULT;
		nm = compat_alloc_user_space(alloc_size);
		if (copy_to_user(nm, nodes_addr(bm), alloc_size))
			return -EFAULT;
	}

	return kernel_mbind(start, len, mode, nm, nr_bits+1, flags);
}

Project: linux
File: mempolicy.c

static void sp_delete(struct shared_policy *sp, struct sp_node *n)
{
	pr_debug("deleting %lx-l%lx\n", n->start, n->end);
	rb_erase(&n->nd, &sp->root);
	sp_free(n);
}

Project: linux
File: mempolicy.c

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);

	pr_debug("set_shared_policy %lx sz %lu %d %d %lx\n",
		 vma->vm_pgoff,
		 sz, npol ? npol->mode : -1,
		 npol ? npol->flags : -1,
		 npol ? nodes_addr(npol->v.nodes)[0] : NUMA_NO_NODE);

	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)
		sp_free(new);
	return err;
}

Project: linux
File: mempolicy.c

static int kernel_migrate_pages(pid_t pid, unsigned long maxnode,
				const unsigned long __user *old_nodes,
				const unsigned long __user *new_nodes)
{
	struct mm_struct *mm = NULL;
	struct task_struct *task;
	nodemask_t task_nodes;
	int err;
	nodemask_t *old;
	nodemask_t *new;
	NODEMASK_SCRATCH(scratch);

	if (!scratch)
		return -ENOMEM;

	old = &scratch->mask1;
	new = &scratch->mask2;

	err = get_nodes(old, old_nodes, maxnode);
	if (err)
		goto out;

	err = get_nodes(new, new_nodes, maxnode);
	if (err)
		goto out;

	/* Find the mm_struct */
	rcu_read_lock();
	task = pid ? find_task_by_vpid(pid) : current;
	if (!task) {
		rcu_read_unlock();
		err = -ESRCH;
		goto out;
	}
	get_task_struct(task);

	err = -EINVAL;

	/*
	 * Check if this process has the right to modify the specified process.
	 * Use the regular "ptrace_may_access()" checks.
	 */
	if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) {
		rcu_read_unlock();
		err = -EPERM;
		goto out_put;
	}
	rcu_read_unlock();

	task_nodes = cpuset_mems_allowed(task);
	/* Is the user allowed to access the target nodes? */
	if (!nodes_subset(*new, task_nodes) && !capable(CAP_SYS_NICE)) {
		err = -EPERM;
		goto out_put;
	}

	task_nodes = cpuset_mems_allowed(current);
	nodes_and(*new, *new, task_nodes);
	if (nodes_empty(*new))
		goto out_put;

	err = security_task_movememory(task);
	if (err)
		goto out_put;

	mm = get_task_mm(task);
	put_task_struct(task);

	if (!mm) {
		err = -EINVAL;
		goto out;
	}

	err = do_migrate_pages(mm, old, new,
		capable(CAP_SYS_NICE) ? MPOL_MF_MOVE_ALL : MPOL_MF_MOVE);

	mmput(mm);
out:
	NODEMASK_SCRATCH_FREE(scratch);

	return err;

out_put:
	put_task_struct(task);
	goto out;

}

Project: linux
File: mempolicy.c

static void mpol_rebind_policy(struct mempolicy *pol, const nodemask_t *newmask)
{
	if (!pol)
		return;
	if (!mpol_store_user_nodemask(pol) && !(pol->flags & MPOL_F_LOCAL) &&
	    nodes_equal(pol->w.cpuset_mems_allowed, *newmask))
		return;

	mpol_ops[pol->mode].rebind(pol, newmask);
}

Project: linux
File: mempolicy.c

unsigned long change_prot_numa(struct vm_area_struct *vma,
			unsigned long addr, unsigned long end)
{
	int nr_updated;

	nr_updated = change_protection(vma, addr, end, PAGE_NONE, 0, 1);
	if (nr_updated)
		count_vm_numa_events(NUMA_PTE_UPDATES, nr_updated);

	return nr_updated;
}

Project: linux
File: mempolicy.c

static int queue_pages_pte_range(pmd_t *pmd, unsigned long addr,
			unsigned long end, struct mm_walk *walk)
{
	struct vm_area_struct *vma = walk->vma;
	struct page *page;
	struct queue_pages *qp = walk->private;
	unsigned long flags = qp->flags;
	int ret;
	bool has_unmovable = false;
	pte_t *pte;
	spinlock_t *ptl;

	ptl = pmd_trans_huge_lock(pmd, vma);
	if (ptl) {
		ret = queue_pages_pmd(pmd, ptl, addr, end, walk);
		if (ret != 2)
			return ret;
	}
	/* THP was split, fall through to pte walk */

	if (pmd_trans_unstable(pmd))
		return 0;

	pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
	for (; addr != end; pte++, addr += PAGE_SIZE) {
		if (!pte_present(*pte))
			continue;
		page = vm_normal_page(vma, addr, *pte);
		if (!page)
			continue;
		/*
		 * vm_normal_page() filters out zero pages, but there might
		 * still be PageReserved pages to skip, perhaps in a VDSO.
		 */
		if (PageReserved(page))
			continue;
		if (!queue_pages_required(page, qp))
			continue;
		if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
			/* MPOL_MF_STRICT must be specified if we get here */
			if (!vma_migratable(vma)) {
				has_unmovable = true;
				break;
			}

			/*
			 * Do not abort immediately since there may be
			 * temporary off LRU pages in the range.  Still
			 * need migrate other LRU pages.
			 */
			if (migrate_page_add(page, qp->pagelist, flags))
				has_unmovable = true;
		} else
			break;
	}
	pte_unmap_unlock(pte - 1, ptl);
	cond_resched();

	if (has_unmovable)
		return 1;

	return addr != end ? -EIO : 0;
}

Project: linux
File: mempolicy.c

struct mempolicy *__mpol_dup(struct mempolicy *old)
{
	struct mempolicy *new = kmem_cache_alloc(policy_cache, GFP_KERNEL);

	if (!new)
		return ERR_PTR(-ENOMEM);

	/* task's mempolicy is protected by alloc_lock */
	if (old == current->mempolicy) {
		task_lock(current);
		*new = *old;
		task_unlock(current);
	} else
		*new = *old;

	if (current_cpuset_is_being_rebound()) {
		nodemask_t mems = cpuset_mems_allowed(current);
		mpol_rebind_policy(new, &mems);
	}
	atomic_set(&new->refcnt, 1);
	return new;
}

Project: linux
File: mempolicy.c

static void get_policy_nodemask(struct mempolicy *p, nodemask_t *nodes)
{
	nodes_clear(*nodes);
	if (p == &default_policy)
		return;

	switch (p->mode) {
	case MPOL_BIND:
		/* Fall through */
	case MPOL_INTERLEAVE:
		*nodes = p->v.nodes;
		break;
	case MPOL_PREFERRED:
		if (!(p->flags & MPOL_F_LOCAL))
			node_set(p->v.preferred_node, *nodes);
		/* else return empty node mask for local allocation */
		break;
	default:
		BUG();
	}
}

Project: linux
File: mempolicy.c

alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
		unsigned long addr, int node, bool hugepage)
{
	struct mempolicy *pol;
	struct page *page;
	int preferred_nid;
	nodemask_t *nmask;

	pol = get_vma_policy(vma, addr);

	if (pol->mode == MPOL_INTERLEAVE) {
		unsigned nid;

		nid = interleave_nid(pol, vma, addr, PAGE_SHIFT + order);
		mpol_cond_put(pol);
		page = alloc_page_interleave(gfp, order, nid);
		goto out;
	}

	if (unlikely(IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && hugepage)) {
		int hpage_node = node;

		/*
		 * For hugepage allocation and non-interleave policy which
		 * allows the current node (or other explicitly preferred
		 * node) we only try to allocate from the current/preferred
		 * node and don't fall back to other nodes, as the cost of
		 * remote accesses would likely offset THP benefits.
		 *
		 * If the policy is interleave, or does not allow the current
		 * node in its nodemask, we allocate the standard way.
		 */
		if (pol->mode == MPOL_PREFERRED && !(pol->flags & MPOL_F_LOCAL))
			hpage_node = pol->v.preferred_node;

		nmask = policy_nodemask(gfp, pol);
		if (!nmask || node_isset(hpage_node, *nmask)) {
			mpol_cond_put(pol);
			/*
			 * First, try to allocate THP only on local node, but
			 * don't reclaim unnecessarily, just compact.
			 */
			page = __alloc_pages_node(hpage_node,
				gfp | __GFP_THISNODE | __GFP_NORETRY, order);

			/*
			 * If hugepage allocations are configured to always
			 * synchronous compact or the vma has been madvised
			 * to prefer hugepage backing, retry allowing remote
			 * memory with both reclaim and compact as well.
			 */
			if (!page && (gfp & __GFP_DIRECT_RECLAIM))
				page = __alloc_pages_node(hpage_node,
								gfp, order);

			goto out;
		}
	}

	nmask = policy_nodemask(gfp, pol);
	preferred_nid = policy_node(gfp, pol, node);
	page = __alloc_pages_nodemask(gfp, order, preferred_nid, nmask);
	mpol_cond_put(pol);
out:
	return page;
}

Project: linux
File: mempolicy.c

static inline void __init check_numabalancing_enable(void)
{
}

Project: linux
File: mempolicy.c

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);
}

Project: linux
File: mempolicy.c

struct mempolicy *get_task_policy(struct task_struct *p)
{
	struct mempolicy *pol = p->mempolicy;
	int node;

	if (pol)
		return pol;

	node = numa_node_id();
	if (node != NUMA_NO_NODE) {
		pol = &preferred_node_policy[node];
		/* preferred_node_policy is not initialised early in boot */
		if (pol->mode)
			return pol;
	}

	return &default_policy;
}

Project: linux
File: mempolicy.c

static int get_nodes(nodemask_t *nodes, const unsigned long __user *nmask,
		     unsigned long maxnode)
{
	unsigned long k;
	unsigned long t;
	unsigned long nlongs;
	unsigned long endmask;

	--maxnode;
	nodes_clear(*nodes);
	if (maxnode == 0 || !nmask)
		return 0;
	if (maxnode > PAGE_SIZE*BITS_PER_BYTE)
		return -EINVAL;

	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 maxnode have more longs than MAX_NUMNODES, check
	 * the bits in that area first. And then go through to
	 * check the rest bits which equal or bigger than MAX_NUMNODES.
	 * Otherwise, just check bits [MAX_NUMNODES, maxnode).
	 */
	if (nlongs > BITS_TO_LONGS(MAX_NUMNODES)) {
		for (k = BITS_TO_LONGS(MAX_NUMNODES); k < nlongs; k++) {
			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 (maxnode > MAX_NUMNODES && MAX_NUMNODES % BITS_PER_LONG != 0) {
		unsigned long valid_mask = endmask;

		valid_mask &= ~((1UL << (MAX_NUMNODES % BITS_PER_LONG)) - 1);
		if (get_user(t, nmask + nlongs - 1))
			return -EFAULT;
		if (t & valid_mask)
			return -EINVAL;
	}

	if (copy_from_user(nodes_addr(*nodes), nmask, nlongs*sizeof(unsigned long)))
		return -EFAULT;
	nodes_addr(*nodes)[nlongs-1] &= endmask;
	return 0;
}

Project: linux
File: mempolicy.c

bool vma_migratable(struct vm_area_struct *vma)
{
	if (vma->vm_flags & (VM_IO | VM_PFNMAP))
		return false;

	/*
	 * DAX device mappings require predictable access latency, so avoid
	 * incurring periodic faults.
	 */
	if (vma_is_dax(vma))
		return false;

	if (is_vm_hugetlb_page(vma) &&
		!hugepage_migration_supported(hstate_vma(vma)))
		return false;

	/*
	 * Migration allocates pages in the highest zone. If we cannot
	 * do so then migration (at least from node to node) is not
	 * possible.
	 */
	if (vma->vm_file &&
		gfp_zone(mapping_gfp_mask(vma->vm_file->f_mapping))
			< policy_zone)
		return false;
	return true;
}

Project: linux
File: mempolicy.c

int vma_dup_policy(struct vm_area_struct *src, struct vm_area_struct *dst)
{
	struct mempolicy *pol = mpol_dup(vma_policy(src));

	if (IS_ERR(pol))
		return PTR_ERR(pol);
	dst->vm_policy = pol;
	return 0;
}

Project: linux
File: mempolicy.c

int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from,
		     const nodemask_t *to, int flags)
{
	int busy = 0;
	int err;
	nodemask_t tmp;

	err = migrate_prep();
	if (err)
		return err;

	down_read(&mm->mmap_sem);

	/*
	 * Find a 'source' bit set in 'tmp' whose corresponding 'dest'
	 * bit in 'to' is not also set in 'tmp'.  Clear the found 'source'
	 * bit in 'tmp', and return that <source, dest> pair for migration.
	 * The pair of nodemasks 'to' and 'from' define the map.
	 *
	 * If no pair of bits is found that way, fallback to picking some
	 * pair of 'source' and 'dest' bits that are not the same.  If the
	 * 'source' and 'dest' bits are the same, this represents a node
	 * that will be migrating to itself, so no pages need move.
	 *
	 * If no bits are left in 'tmp', or if all remaining bits left
	 * in 'tmp' correspond to the same bit in 'to', return false
	 * (nothing left to migrate).
	 *
	 * This lets us pick a pair of nodes to migrate between, such that
	 * if possible the dest node is not already occupied by some other
	 * source node, minimizing the risk of overloading the memory on a
	 * node that would happen if we migrated incoming memory to a node
	 * before migrating outgoing memory source that same node.
	 *
	 * A single scan of tmp is sufficient.  As we go, we remember the
	 * most recent <s, d> pair that moved (s != d).  If we find a pair
	 * that not only moved, but what's better, moved to an empty slot
	 * (d is not set in tmp), then we break out then, with that pair.
	 * Otherwise when we finish scanning from_tmp, we at least have the
	 * most recent <s, d> pair that moved.  If we get all the way through
	 * the scan of tmp without finding any node that moved, much less
	 * moved to an empty node, then there is nothing left worth migrating.
	 */

	tmp = *from;
	while (!nodes_empty(tmp)) {
		int s,d;
		int source = NUMA_NO_NODE;
		int dest = 0;

		for_each_node_mask(s, tmp) {

			/*
			 * do_migrate_pages() tries to maintain the relative
			 * node relationship of the pages established between
			 * threads and memory areas.
                         *
			 * However if the number of source nodes is not equal to
			 * the number of destination nodes we can not preserve
			 * this node relative relationship.  In that case, skip
			 * copying memory from a node that is in the destination
			 * mask.
			 *
			 * Example: [2,3,4] -> [3,4,5] moves everything.
			 *          [0-7] - > [3,4,5] moves only 0,1,2,6,7.
			 */

			if ((nodes_weight(*from) != nodes_weight(*to)) &&
						(node_isset(s, *to)))
				continue;

			d = node_remap(s, *from, *to);
			if (s == d)
				continue;

			source = s;	/* Node moved. Memorize */
			dest = d;

			/* dest not in remaining from nodes? */
			if (!node_isset(dest, tmp))
				break;
		}
		if (source == NUMA_NO_NODE)
			break;

		node_clear(source, tmp);
		err = migrate_to_node(mm, source, dest, flags);
		if (err > 0)
			busy += err;
		if (err < 0)
			break;
	}
	up_read(&mm->mmap_sem);
	if (err < 0)
		return err;
	return busy;

}

Project: linux
File: mempolicy.c

int mpol_parse_str(char *str, struct mempolicy **mpol)
{
	struct mempolicy *new = NULL;
	unsigned short mode_flags;
	nodemask_t nodes;
	char *nodelist = strchr(str, ':');
	char *flags = strchr(str, '=');
	int err = 1, mode;

	if (flags)
		*flags++ = '\0';	/* terminate mode string */

	if (nodelist) {
		/* NUL-terminate mode or flags string */
		*nodelist++ = '\0';
		if (nodelist_parse(nodelist, nodes))
			goto out;
		if (!nodes_subset(nodes, node_states[N_MEMORY]))
			goto out;
	} else
		nodes_clear(nodes);

	mode = match_string(policy_modes, MPOL_MAX, str);
	if (mode < 0)
		goto out;

	switch (mode) {
	case MPOL_PREFERRED:
		/*
		 * Insist on a nodelist of one node only, although later
		 * we use first_node(nodes) to grab a single node, so here
		 * nodelist (or nodes) cannot be empty.
		 */
		if (nodelist) {
			char *rest = nodelist;
			while (isdigit(*rest))
				rest++;
			if (*rest)
				goto out;
			if (nodes_empty(nodes))
				goto out;
		}
		break;
	case MPOL_INTERLEAVE:
		/*
		 * Default to online nodes with memory if no nodelist
		 */
		if (!nodelist)
			nodes = node_states[N_MEMORY];
		break;
	case MPOL_LOCAL:
		/*
		 * Don't allow a nodelist;  mpol_new() checks flags
		 */
		if (nodelist)
			goto out;
		mode = MPOL_PREFERRED;
		break;
	case MPOL_DEFAULT:
		/*
		 * Insist on a empty nodelist
		 */
		if (!nodelist)
			err = 0;
		goto out;
	case MPOL_BIND:
		/*
		 * Insist on a nodelist
		 */
		if (!nodelist)
			goto out;
	}

	mode_flags = 0;
	if (flags) {
		/*
		 * Currently, we only support two mutually exclusive
		 * mode flags.
		 */
		if (!strcmp(flags, "static"))
			mode_flags |= MPOL_F_STATIC_NODES;
		else if (!strcmp(flags, "relative"))
			mode_flags |= MPOL_F_RELATIVE_NODES;
		else
			goto out;
	}

	new = mpol_new(mode, mode_flags, &nodes);
	if (IS_ERR(new))
		goto out;

	/*
	 * Save nodes for mpol_to_str() to show the tmpfs mount options
	 * for /proc/mounts, /proc/pid/mounts and /proc/pid/mountinfo.
	 */
	if (mode != MPOL_PREFERRED)
		new->v.nodes = nodes;
	else if (nodelist)
		new->v.preferred_node = first_node(nodes);
	else
		new->flags |= MPOL_F_LOCAL;

	/*
	 * Save nodes for contextualization: this will be used to "clone"
	 * the mempolicy in a specific context [cpuset] at a later time.
	 */
	new->w.user_nodemask = nodes;

	err = 0;

out:
	/* Restore string for error message */
	if (nodelist)
		*--nodelist = ':';
	if (flags)
		*--flags = '=';
	if (!err)
		*mpol = new;
	return err;
}

Project: linux
File: mempolicy.c

static unsigned offset_il_node(struct mempolicy *pol, unsigned long n)
{
	unsigned nnodes = nodes_weight(pol->v.nodes);
	unsigned target;
	int i;
	int nid;

	if (!nnodes)
		return numa_node_id();
	target = (unsigned int)n % nnodes;
	nid = first_node(pol->v.nodes);
	for (i = 0; i < target; i++)
		nid = next_node(nid, pol->v.nodes);
	return nid;
}

Project: linux
File: mempolicy.c

static struct page *alloc_page_interleave(gfp_t gfp, unsigned order,
					unsigned nid)
{
	struct page *page;

	page = __alloc_pages(gfp, order, nid);
	/* skip NUMA_INTERLEAVE_HIT counter update if numa stats is disabled */
	if (!static_branch_likely(&vm_numa_stat_key))
		return page;
	if (page && page_to_nid(page) == nid) {
		preempt_disable();
		__inc_numa_state(page_zone(page), NUMA_INTERLEAVE_HIT);
		preempt_enable();
	}
	return page;
}

Project: linux
File: mempolicy.c

bool __mpol_equal(struct mempolicy *a, struct mempolicy *b)
{
	if (!a || !b)
		return false;
	if (a->mode != b->mode)
		return false;
	if (a->flags != b->flags)
		return false;
	if (mpol_store_user_nodemask(a))
		if (!nodes_equal(a->w.user_nodemask, b->w.user_nodemask))
			return false;

	switch (a->mode) {
	case MPOL_BIND:
		/* Fall through */
	case MPOL_INTERLEAVE:
		return !!nodes_equal(a->v.nodes, b->v.nodes);
	case MPOL_PREFERRED:
		/* a's ->flags is the same as b's */
		if (a->flags & MPOL_F_LOCAL)
			return true;
		return a->v.preferred_node == b->v.preferred_node;
	default:
		BUG();
		return false;
	}
}

Project: linux
File: mempolicy.c

static long do_mbind(unsigned long start, unsigned long len,
		     unsigned short mode, unsigned short mode_flags,
		     nodemask_t *nmask, unsigned long flags)
{
	struct mm_struct *mm = current->mm;
	struct mempolicy *new;
	unsigned long end;
	int err;
	int ret;
	LIST_HEAD(pagelist);

	if (flags & ~(unsigned long)MPOL_MF_VALID)
		return -EINVAL;
	if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
		return -EPERM;

	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;

	new = mpol_new(mode, mode_flags, nmask);
	if (IS_ERR(new))
		return PTR_ERR(new);

	if (flags & MPOL_MF_LAZY)
		new->flags |= MPOL_F_MOF;

	/*
	 * If we are using the default policy then operation
	 * on discontinuous address spaces is okay after all
	 */
	if (!new)
		flags |= MPOL_MF_DISCONTIG_OK;

	pr_debug("mbind %lx-%lx mode:%d flags:%d nodes:%lx\n",
		 start, start + len, mode, mode_flags,
		 nmask ? nodes_addr(*nmask)[0] : NUMA_NO_NODE);

	if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {

		err = migrate_prep();
		if (err)
			goto mpol_out;
	}
	{
		NODEMASK_SCRATCH(scratch);
		if (scratch) {
			down_write(&mm->mmap_sem);
			task_lock(current);
			err = mpol_set_nodemask(new, nmask, scratch);
			task_unlock(current);
			if (err)
				up_write(&mm->mmap_sem);
		} else
			err = -ENOMEM;
		NODEMASK_SCRATCH_FREE(scratch);
	}
	if (err)
		goto mpol_out;

	ret = queue_pages_range(mm, start, end, nmask,
			  flags | MPOL_MF_INVERT, &pagelist);

	if (ret < 0) {
		err = ret;
		goto up_out;
	}

	err = mbind_range(mm, start, end, new);

	if (!err) {
		int nr_failed = 0;

		if (!list_empty(&pagelist)) {
			WARN_ON_ONCE(flags & MPOL_MF_LAZY);
			nr_failed = migrate_pages(&pagelist, new_page, NULL,
				start, MIGRATE_SYNC, MR_MEMPOLICY_MBIND);
			if (nr_failed)
				putback_movable_pages(&pagelist);
		}

		if ((ret > 0) || (nr_failed && (flags & MPOL_MF_STRICT)))
			err = -EIO;
	} else {
up_out:
		if (!list_empty(&pagelist))
			putback_movable_pages(&pagelist);
	}

	up_write(&mm->mmap_sem);
mpol_out:
	mpol_put(new);
	return err;
}

Project: linux
File: mempolicy.c

static void sp_node_init(struct sp_node *node, unsigned long start,
			unsigned long end, struct mempolicy *pol)
{
	node->start = start;
	node->end = end;
	node->policy = pol;
}

Project: linux
File: mempolicy.c

static int queue_pages_pmd(pmd_t *pmd, spinlock_t *ptl, unsigned long addr,
				unsigned long end, struct mm_walk *walk)
{
	int ret = 0;
	struct page *page;
	struct queue_pages *qp = walk->private;
	unsigned long flags;

	if (unlikely(is_pmd_migration_entry(*pmd))) {
		ret = -EIO;
		goto unlock;
	}
	page = pmd_page(*pmd);
	if (is_huge_zero_page(page)) {
		spin_unlock(ptl);
		__split_huge_pmd(walk->vma, pmd, addr, false, NULL);
		ret = 2;
		goto out;
	}
	if (!queue_pages_required(page, qp))
		goto unlock;

	flags = qp->flags;
	/* go to thp migration */
	if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
		if (!vma_migratable(walk->vma) ||
		    migrate_page_add(page, qp->pagelist, flags)) {
			ret = 1;
			goto unlock;
		}
	} else
		ret = -EIO;
unlock:
	spin_unlock(ptl);
out:
	return ret;
}

Project: linux
File: mempolicy.c

struct mempolicy *__get_vma_policy(struct vm_area_struct *vma,
						unsigned long addr)
{
	struct mempolicy *pol = NULL;

	if (vma) {
		if (vma->vm_ops && vma->vm_ops->get_policy) {
			pol = vma->vm_ops->get_policy(vma, addr);
		} else if (vma->vm_policy) {
			pol = vma->vm_policy;

			/*
			 * shmem_alloc_page() passes MPOL_F_SHARED policy with
			 * a pseudo vma whose vma->vm_ops=NULL. Take a reference
			 * count on these policies which will be dropped by
			 * mpol_cond_put() later
			 */
			if (mpol_needs_cond_ref(pol))
				mpol_get(pol);
		}
	}

	return pol;
}

Project: linux
File: mempolicy.c

void mpol_put_task_policy(struct task_struct *task)
{
	struct mempolicy *pol;

	task_lock(task);
	pol = task->mempolicy;
	task->mempolicy = NULL;
	task_unlock(task);
	mpol_put(pol);
}

Project: linux
File: mempolicy.c

static struct page *new_page(struct page *page, unsigned long start)
{
	struct vm_area_struct *vma;
	unsigned long uninitialized_var(address);

	vma = find_vma(current->mm, start);
	while (vma) {
		address = page_address_in_vma(page, vma);
		if (address != -EFAULT)
			break;
		vma = vma->vm_next;
	}

	if (PageHuge(page)) {
		return alloc_huge_page_vma(page_hstate(compound_head(page)),
				vma, address);
	} else if (PageTransHuge(page)) {
		struct page *thp;

		thp = alloc_hugepage_vma(GFP_TRANSHUGE, vma, address,
					 HPAGE_PMD_ORDER);
		if (!thp)
			return NULL;
		prep_transhuge_page(thp);
		return thp;
	}
	/*
	 * if !vma, alloc_page_vma() will use task or system default policy
	 */
	return alloc_page_vma(GFP_HIGHUSER_MOVABLE | __GFP_RETRY_MAYFAIL,
			vma, address);
}

Project: linux
File: mempolicy.c

unsigned int mempolicy_slab_node(void)
{
	struct mempolicy *policy;
	int node = numa_mem_id();

	if (in_interrupt())
		return node;

	policy = current->mempolicy;
	if (!policy || policy->flags & MPOL_F_LOCAL)
		return node;

	switch (policy->mode) {
	case MPOL_PREFERRED:
		/*
		 * handled MPOL_F_LOCAL above
		 */
		return policy->v.preferred_node;

	case MPOL_INTERLEAVE:
		return interleave_nodes(policy);

	case MPOL_BIND: {
		struct zoneref *z;

		/*
		 * Follow bind policy behavior and start allocation at the
		 * first node.
		 */
		struct zonelist *zonelist;
		enum zone_type highest_zoneidx = gfp_zone(GFP_KERNEL);
		zonelist = &NODE_DATA(node)->node_zonelists[ZONELIST_FALLBACK];
		z = first_zones_zonelist(zonelist, highest_zoneidx,
							&policy->v.nodes);
		return z->zone ? zone_to_nid(z->zone) : node;
	}

	default:
		BUG();
	}
}

Project: linux
File: mempolicy.c

static int mpol_new_interleave(struct mempolicy *pol, const nodemask_t *nodes)
{
	if (nodes_empty(*nodes))
		return -EINVAL;
	pol->v.nodes = *nodes;
	return 0;
}

Project: linux
File: mempolicy.c

static struct sp_node *sp_alloc(unsigned long start, unsigned long end,
				struct mempolicy *pol)
{
	struct sp_node *n;
	struct mempolicy *newpol;

	n = kmem_cache_alloc(sn_cache, GFP_KERNEL);
	if (!n)
		return NULL;

	newpol = mpol_dup(pol);
	if (IS_ERR(newpol)) {
		kmem_cache_free(sn_cache, n);
		return NULL;
	}
	newpol->flags |= MPOL_F_SHARED;
	sp_node_init(n, start, end, newpol);

	return n;
}

Project: linux
File: mempolicy.c

static int mbind_range(struct mm_struct *mm, unsigned long start,
		       unsigned long end, struct mempolicy *new_pol)
{
	struct vm_area_struct *next;
	struct vm_area_struct *prev;
	struct vm_area_struct *vma;
	int err = 0;
	pgoff_t pgoff;
	unsigned long vmstart;
	unsigned long vmend;

	vma = find_vma(mm, start);
	VM_BUG_ON(!vma);

	prev = vma->vm_prev;
	if (start > vma->vm_start)
		prev = vma;

	for (; vma && vma->vm_start < end; prev = vma, vma = next) {
		next = vma->vm_next;
		vmstart = max(start, vma->vm_start);
		vmend   = min(end, vma->vm_end);

		if (mpol_equal(vma_policy(vma), new_pol))
			continue;

		pgoff = vma->vm_pgoff +
			((vmstart - vma->vm_start) >> PAGE_SHIFT);
		prev = vma_merge(mm, prev, vmstart, vmend, vma->vm_flags,
				 vma->anon_vma, vma->vm_file, pgoff,
				 new_pol, vma->vm_userfaultfd_ctx);
		if (prev) {
			vma = prev;
			next = vma->vm_next;
			if (mpol_equal(vma_policy(vma), new_pol))
				continue;
			/* vma_merge() joined vma && vma->next, case 8 */
			goto replace;
		}
		if (vma->vm_start != vmstart) {
			err = split_vma(vma->vm_mm, vma, vmstart, 1);
			if (err)
				goto out;
		}
		if (vma->vm_end != vmend) {
			err = split_vma(vma->vm_mm, vma, vmend, 0);
			if (err)
				goto out;
		}
 replace:
		err = vma_replace_policy(vma, new_pol);
		if (err)
			goto out;
	}

 out:
	return err;
}

Project: linux
File: mempolicy.c

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);
	pr_debug("inserting %lx-%lx: %d\n", new->start, new->end,
		 new->policy ? new->policy->mode : 0);
}

Project: linux
File: mempolicy.c

void __mpol_put(struct mempolicy *p)
{
	if (!atomic_dec_and_test(&p->refcnt))
		return;
	kmem_cache_free(policy_cache, p);
}

Project: linux
File: mempolicy.c

void mpol_free_shared_policy(struct shared_policy *p)
{
	struct sp_node *n;
	struct rb_node *next;

	if (!p->root.rb_node)
		return;
	write_lock(&p->lock);
	next = rb_first(&p->root);
	while (next) {
		n = rb_entry(next, struct sp_node, nd);
		next = rb_next(&n->nd);
		sp_delete(p, n);
	}
	write_unlock(&p->lock);
}

Project: linux
File: mempolicy.c

void mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
{
	char *p = buffer;
	nodemask_t nodes = NODE_MASK_NONE;
	unsigned short mode = MPOL_DEFAULT;
	unsigned short flags = 0;

	if (pol && pol != &default_policy && !(pol->flags & MPOL_F_MORON)) {
		mode = pol->mode;
		flags = pol->flags;
	}

	switch (mode) {
	case MPOL_DEFAULT:
		break;
	case MPOL_PREFERRED:
		if (flags & MPOL_F_LOCAL)
			mode = MPOL_LOCAL;
		else
			node_set(pol->v.preferred_node, nodes);
		break;
	case MPOL_BIND:
	case MPOL_INTERLEAVE:
		nodes = pol->v.nodes;
		break;
	default:
		WARN_ON_ONCE(1);
		snprintf(p, maxlen, "unknown");
		return;
	}

	p += snprintf(p, maxlen, "%s", policy_modes[mode]);

	if (flags & MPOL_MODE_FLAGS) {
		p += snprintf(p, buffer + maxlen - p, "=");

		/*
		 * Currently, the only defined flags are mutually exclusive
		 */
		if (flags & MPOL_F_STATIC_NODES)
			p += snprintf(p, buffer + maxlen - p, "static");
		else if (flags & MPOL_F_RELATIVE_NODES)
			p += snprintf(p, buffer + maxlen - p, "relative");
	}

	if (!nodes_empty(nodes))
		p += scnprintf(p, buffer + maxlen - p, ":%*pbl",
			       nodemask_pr_args(&nodes));
}

Project: linux
File: mempolicy.c

static void mpol_relative_nodemask(nodemask_t *ret, const nodemask_t *orig,
				   const nodemask_t *rel)
{
	nodemask_t tmp;
	nodes_fold(tmp, *orig, nodes_weight(*rel));
	nodes_onto(*ret, tmp, *rel);
}

Project: linux
File: mempolicy.c

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;
	read_lock(&sp->lock);
	sn = sp_lookup(sp, idx, idx+1);
	if (sn) {
		mpol_get(sn->policy);
		pol = sn->policy;
	}
	read_unlock(&sp->lock);
	return pol;
}

Project: linux
File: mempolicy.c

static unsigned long change_prot_numa(struct vm_area_struct *vma,
			unsigned long addr, unsigned long end)
{
	return 0;
}

Project: linux
File: mempolicy.c

bool mempolicy_nodemask_intersects(struct task_struct *tsk,
					const nodemask_t *mask)
{
	struct mempolicy *mempolicy;
	bool ret = true;

	if (!mask)
		return ret;
	task_lock(tsk);
	mempolicy = tsk->mempolicy;
	if (!mempolicy)
		goto out;

	switch (mempolicy->mode) {
	case MPOL_PREFERRED:
		/*
		 * MPOL_PREFERRED and MPOL_F_LOCAL are only preferred nodes to
		 * allocate from, they may fallback to other nodes when oom.
		 * Thus, it's possible for tsk to have allocated memory from
		 * nodes in mask.
		 */
		break;
	case MPOL_BIND:
	case MPOL_INTERLEAVE:
		ret = nodes_intersects(mempolicy->v.nodes, *mask);
		break;
	default:
		BUG();
	}
out:
	task_unlock(tsk);
	return ret;
}

Project: linux
File: mempolicy.c

SYSCALL_DEFINE6(mbind, unsigned long, start, unsigned long, len,
		unsigned long, mode, const unsigned long __user *, nmask,
		unsigned long, maxnode, unsigned int, flags)
{
	return kernel_mbind(start, len, mode, nmask, maxnode, flags);
}

Project: linux
File: mempolicy.c

static int copy_nodes_to_user(unsigned long __user *mask, unsigned long maxnode,
			      nodemask_t *nodes)
{
	unsigned long copy = ALIGN(maxnode-1, 64) / 8;
	unsigned int nbytes = BITS_TO_LONGS(nr_node_ids) * sizeof(long);

	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_addr(*nodes), copy) ? -EFAULT : 0;
}

Project: linux
File: mempolicy.c

SYSCALL_DEFINE3(set_mempolicy, int, mode, const unsigned long __user *, nmask,
		unsigned long, maxnode)
{
	return kernel_set_mempolicy(mode, nmask, maxnode);
}

Project: linux
File: mempolicy.c

COMPAT_SYSCALL_DEFINE3(set_mempolicy, int, mode, compat_ulong_t __user *, nmask,
		       compat_ulong_t, maxnode)
{
	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) {
		if (compat_get_bitmap(bm, nmask, nr_bits))
			return -EFAULT;
		nm = compat_alloc_user_space(alloc_size);
		if (copy_to_user(nm, bm, alloc_size))
			return -EFAULT;
	}

	return kernel_set_mempolicy(mode, nm, nr_bits+1);
}

Project: linux
File: mempolicy.c

static int migrate_to_node(struct mm_struct *mm, int source, int dest,
			   int flags)
{
	nodemask_t nmask;
	LIST_HEAD(pagelist);
	int err = 0;

	nodes_clear(nmask);
	node_set(source, nmask);

	/*
	 * This does not "check" the range but isolates all pages that
	 * need migration.  Between passing in the full user address
	 * space range and MPOL_MF_DISCONTIG_OK, this call can not fail.
	 */
	VM_BUG_ON(!(flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)));
	queue_pages_range(mm, mm->mmap->vm_start, mm->task_size, &nmask,
			flags | MPOL_MF_DISCONTIG_OK, &pagelist);

	if (!list_empty(&pagelist)) {
		err = migrate_pages(&pagelist, alloc_new_node_page, NULL, dest,
					MIGRATE_SYNC, MR_SYSCALL);
		if (err)
			putback_movable_pages(&pagelist);
	}

	return err;
}

Project: linux
File: mempolicy.c

SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,
		const unsigned long __user *, old_nodes,
		const unsigned long __user *, new_nodes)
{
	return kernel_migrate_pages(pid, maxnode, old_nodes, new_nodes);
}

Project: linux
File: mempolicy.c

static inline bool queue_pages_required(struct page *page,
					struct queue_pages *qp)
{
	int nid = page_to_nid(page);
	unsigned long flags = qp->flags;

	return node_isset(nid, *qp->nmask) == !(flags & MPOL_MF_INVERT);
}

Project: linux
File: mempolicy.c

COMPAT_SYSCALL_DEFINE4(migrate_pages, compat_pid_t, pid,
		       compat_ulong_t, maxnode,
		       const compat_ulong_t __user *, old_nodes,
		       const compat_ulong_t __user *, new_nodes)
{
	unsigned long __user *old = NULL;
	unsigned long __user *new = NULL;
	nodemask_t tmp_mask;
	unsigned long nr_bits;
	unsigned long size;

	nr_bits = min_t(unsigned long, maxnode - 1, MAX_NUMNODES);
	size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
	if (old_nodes) {
		if (compat_get_bitmap(nodes_addr(tmp_mask), old_nodes, nr_bits))
			return -EFAULT;
		old = compat_alloc_user_space(new_nodes ? size * 2 : size);
		if (new_nodes)
			new = old + size / sizeof(unsigned long);
		if (copy_to_user(old, nodes_addr(tmp_mask), size))
			return -EFAULT;
	}
	if (new_nodes) {
		if (compat_get_bitmap(nodes_addr(tmp_mask), new_nodes, nr_bits))
			return -EFAULT;
		if (new == NULL)
			new = compat_alloc_user_space(size);
		if (copy_to_user(new, nodes_addr(tmp_mask), size))
			return -EFAULT;
	}
	return kernel_migrate_pages(pid, nr_bits + 1, old, new);
}

Project: linux
File: mempolicy.c

static int queue_pages_test_walk(unsigned long start, unsigned long end,
				struct mm_walk *walk)
{
	struct vm_area_struct *vma = walk->vma;
	struct queue_pages *qp = walk->private;
	unsigned long endvma = vma->vm_end;
	unsigned long flags = qp->flags;

	/* range check first */
	VM_BUG_ON_VMA((vma->vm_start > start) || (vma->vm_end < end), vma);

	if (!qp->first) {
		qp->first = vma;
		if (!(flags & MPOL_MF_DISCONTIG_OK) &&
			(qp->start < vma->vm_start))
			/* hole at head side of range */
			return -EFAULT;
	}
	if (!(flags & MPOL_MF_DISCONTIG_OK) &&
		((vma->vm_end < qp->end) &&
		(!vma->vm_next || vma->vm_end < vma->vm_next->vm_start)))
		/* hole at middle or tail of range */
		return -EFAULT;

	/*
	 * Need check MPOL_MF_STRICT to return -EIO if possible
	 * regardless of vma_migratable
	 */
	if (!vma_migratable(vma) &&
	    !(flags & MPOL_MF_STRICT))
		return 1;

	if (endvma > end)
		endvma = end;

	if (flags & MPOL_MF_LAZY) {
		/* Similar to task_numa_work, skip inaccessible VMAs */
		if (!is_vm_hugetlb_page(vma) &&
			(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)) &&
			!(vma->vm_flags & VM_MIXEDMAP))
			change_prot_numa(vma, start, endvma);
		return 1;
	}

	/* queue pages from current vma */
	if (flags & MPOL_MF_VALID)
		return 0;
	return 1;
}

Project: linux
File: mempolicy.c

void mpol_shared_policy_init(struct shared_policy *sp, struct mempolicy *mpol)
{
	int ret;

	sp->root = RB_ROOT;		/* empty tree == default mempolicy */
	rwlock_init(&sp->lock);

	if (mpol) {
		struct vm_area_struct pvma;
		struct mempolicy *new;
		NODEMASK_SCRATCH(scratch);

		if (!scratch)
			goto put_mpol;
		/* contextualize the tmpfs mount point mempolicy */
		new = mpol_new(mpol->mode, mpol->flags, &mpol->w.user_nodemask);
		if (IS_ERR(new))
			goto free_scratch; /* no valid nodemask intersection */

		task_lock(current);
		ret = mpol_set_nodemask(new, &mpol->w.user_nodemask, scratch);
		task_unlock(current);
		if (ret)
			goto put_new;

		/* Create pseudo-vma that contains just the policy */
		vma_init(&pvma, NULL);
		pvma.vm_end = TASK_SIZE;	/* policy covers entire file */
		mpol_set_shared_policy(sp, &pvma, new); /* adds ref */

put_new:
		mpol_put(new);			/* drop initial ref */
free_scratch:
		NODEMASK_SCRATCH_FREE(scratch);
put_mpol:
		mpol_put(mpol);	/* drop our incoming ref on sb mpol */
	}
}

Project: linux
File: mempolicy.c

void __init numa_policy_init(void)
{
	nodemask_t interleave_nodes;
	unsigned long largest = 0;
	int nid, prefer = 0;

	policy_cache = kmem_cache_create("numa_policy",
					 sizeof(struct mempolicy),
					 0, SLAB_PANIC, NULL);

	sn_cache = kmem_cache_create("shared_policy_node",
				     sizeof(struct sp_node),
				     0, SLAB_PANIC, NULL);

	for_each_node(nid) {
		preferred_node_policy[nid] = (struct mempolicy) {
			.refcnt = ATOMIC_INIT(1),
			.mode = MPOL_PREFERRED,
			.flags = MPOL_F_MOF | MPOL_F_MORON,
			.v = { .preferred_node = nid, },
		};
	}

	/*
	 * Set interleaving policy for system init. Interleaving is only
	 * enabled across suitably sized nodes (default is >= 16MB), or
	 * fall back to the largest node if they're all smaller.
	 */
	nodes_clear(interleave_nodes);
	for_each_node_state(nid, N_MEMORY) {
		unsigned long total_pages = node_present_pages(nid);

		/* Preserve the largest node */
		if (largest < total_pages) {
			largest = total_pages;
			prefer = nid;
		}

		/* Interleave this node? */
		if ((total_pages << PAGE_SHIFT) >= (16 << 20))
			node_set(nid, interleave_nodes);
	}

	/* All too small, use the largest */
	if (unlikely(nodes_empty(interleave_nodes)))
		node_set(prefer, interleave_nodes);

	if (do_set_mempolicy(MPOL_INTERLEAVE, 0, &interleave_nodes))
		pr_err("%s: interleaving failed\n", __func__);

	check_numabalancing_enable();
}

Project: linux
File: mempolicy.c

static void __init check_numabalancing_enable(void)
{
	bool numabalancing_default = false;

	if (IS_ENABLED(CONFIG_NUMA_BALANCING_DEFAULT_ENABLED))
		numabalancing_default = true;

	/* Parsed by setup_numabalancing. override == 1 enables, -1 disables */
	if (numabalancing_override)
		set_numabalancing_state(numabalancing_override == 1);

	if (num_online_nodes() > 1 && !numabalancing_override) {
		pr_info("%s automatic NUMA balancing. Configure with numa_balancing= or the kernel.numa_balancing sysctl\n",
			numabalancing_default ? "Enabling" : "Disabling");
		set_numabalancing_state(numabalancing_default);
	}
}

Project: linux
File: mempolicy.c

bool vma_policy_mof(struct vm_area_struct *vma)
{
	struct mempolicy *pol;

	if (vma->vm_ops && vma->vm_ops->get_policy) {
		bool ret = false;

		pol = vma->vm_ops->get_policy(vma, vma->vm_start);
		if (pol && (pol->flags & MPOL_F_MOF))
			ret = true;
		mpol_cond_put(pol);

		return ret;
	}

	pol = vma->vm_policy;
	if (!pol)
		pol = get_task_policy(current);

	return pol->flags & MPOL_F_MOF;
}

Project: linux
File: mempolicy.c

static int migrate_page_add(struct page *page, struct list_head *pagelist,
				unsigned long flags)
{
	return -EIO;
}

Project: linux
File: mempolicy.c

void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new)
{
	struct vm_area_struct *vma;

	down_write(&mm->mmap_sem);
	for (vma = mm->mmap; vma; vma = vma->vm_next)
		mpol_rebind_policy(vma->vm_policy, new);
	up_write(&mm->mmap_sem);
}

Project: linux
File: mempolicy.c

static inline unsigned interleave_nid(struct mempolicy *pol,
		 struct vm_area_struct *vma, unsigned long addr, int shift)
{
	if (vma) {
		unsigned long off;

		/*
		 * for small pages, there is no difference between
		 * shift and PAGE_SHIFT, so the bit-shift is safe.
		 * for huge pages, since vm_pgoff is in units of small
		 * pages, we need to shift off the always 0 bits to get
		 * a useful offset.
		 */
		BUG_ON(shift < PAGE_SHIFT);
		off = vma->vm_pgoff >> (shift - PAGE_SHIFT);
		off += (addr - vma->vm_start) >> shift;
		return offset_il_node(pol, off);
	} else
		return interleave_nodes(pol);
}

Project: linux
File: mempolicy.c

COMPAT_SYSCALL_DEFINE5(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, nr_node_ids);
	alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;

	if (nmask)
		nm = compat_alloc_user_space(alloc_size);

	err = kernel_get_mempolicy(policy, nm, nr_bits+1, addr, flags);

	if (!err && nmask) {
		unsigned long copy_size;
		copy_size = min_t(unsigned long, sizeof(bm), alloc_size);
		err = copy_from_user(bm, nm, copy_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;
}

Project: linux
File: mempolicy.c

static void sp_free(struct sp_node *n)
{
	mpol_put(n->policy);
	kmem_cache_free(sn_cache, n);
}

Project: linux
File: mempolicy.c

static int lookup_node(struct mm_struct *mm, unsigned long addr)
{
	struct page *p;
	int err;

	int locked = 1;
	err = get_user_pages_locked(addr & PAGE_MASK, 1, 0, &p, &locked);
	if (err >= 0) {
		err = page_to_nid(p);
		put_page(p);
	}
	if (locked)
		up_read(&mm->mmap_sem);
	return err;
}

Project: linux
File: mempolicy.c

static long kernel_set_mempolicy(int mode, const unsigned long __user *nmask,
				 unsigned long maxnode)
{
	int err;
	nodemask_t nodes;
	unsigned short flags;

	flags = mode & MPOL_MODE_FLAGS;
	mode &= ~MPOL_MODE_FLAGS;
	if ((unsigned int)mode >= MPOL_MAX)
		return -EINVAL;
	if ((flags & MPOL_F_STATIC_NODES) && (flags & MPOL_F_RELATIVE_NODES))
		return -EINVAL;
	err = get_nodes(&nodes, nmask, maxnode);
	if (err)
		return err;
	return do_set_mempolicy(mode, flags, &nodes);
}

Project: linux
File: mempolicy.c

static struct mempolicy *get_vma_policy(struct vm_area_struct *vma,
						unsigned long addr)
{
	struct mempolicy *pol = __get_vma_policy(vma, addr);

	if (!pol)
		pol = get_task_policy(current);

	return pol;
}

Project: linux
File: mempolicy.c

bool init_nodemask_of_mempolicy(nodemask_t *mask)
{
	struct mempolicy *mempolicy;
	int nid;

	if (!(mask && current->mempolicy))
		return false;

	task_lock(current);
	mempolicy = current->mempolicy;
	switch (mempolicy->mode) {
	case MPOL_PREFERRED:
		if (mempolicy->flags & MPOL_F_LOCAL)
			nid = numa_node_id();
		else
			nid = mempolicy->v.preferred_node;
		init_nodemask_of_node(mask, nid);
		break;

	case MPOL_BIND:
		/* Fall through */
	case MPOL_INTERLEAVE:
		*mask =  mempolicy->v.nodes;
		break;

	default:
		BUG();
	}
	task_unlock(current);

	return true;
}

Project: linux
File: mempolicy.c

static int queue_pages_hugetlb(pte_t *pte, unsigned long hmask,
			       unsigned long addr, unsigned long end,
			       struct mm_walk *walk)
{
	int ret = 0;
#ifdef CONFIG_HUGETLB_PAGE
	struct queue_pages *qp = walk->private;
	unsigned long flags = (qp->flags & MPOL_MF_VALID);
	struct page *page;
	spinlock_t *ptl;
	pte_t entry;

	ptl = huge_pte_lock(hstate_vma(walk->vma), walk->mm, pte);
	entry = huge_ptep_get(pte);
	if (!pte_present(entry))
		goto unlock;
	page = pte_page(entry);
	if (!queue_pages_required(page, qp))
		goto unlock;

	if (flags == MPOL_MF_STRICT) {
		/*
		 * STRICT alone means only detecting misplaced page and no
		 * need to further check other vma.
		 */
		ret = -EIO;
		goto unlock;
	}

	if (!vma_migratable(walk->vma)) {
		/*
		 * Must be STRICT with MOVE*, otherwise .test_walk() have
		 * stopped walking current vma.
		 * Detecting misplaced page but allow migrating pages which
		 * have been queued.
		 */
		ret = 1;
		goto unlock;
	}

	/* With MPOL_MF_MOVE, we migrate only unshared hugepage. */
	if (flags & (MPOL_MF_MOVE_ALL) ||
	    (flags & MPOL_MF_MOVE && page_mapcount(page) == 1)) {
		if (!isolate_huge_page(page, qp->pagelist) &&
			(flags & MPOL_MF_STRICT))
			/*
			 * Failed to isolate page but allow migrating pages
			 * which have been queued.
			 */
			ret = 1;
	}
unlock:
	spin_unlock(ptl);
#else
	BUG();
#endif
	return ret;
}

Project: linux
File: mempolicy.c

SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
		unsigned long __user *, nmask, unsigned long, maxnode,
		unsigned long, addr, unsigned long, flags)
{
	return kernel_get_mempolicy(policy, nmask, maxnode, addr, flags);
}