From: Yulei Zhang <yuleixzhang@xxxxxxxxxxx>
The belowing figure shows the topology of dmem memory
management, it reserves a few memory regions from the
numa nodes, and in each region it leverages the bitmap to
track the actual memory usage.
+------+-+-------+---------+
| Node0| | ... | NodeN |
+--/-\-+-+-------+---------+
/ \
+---v----+v-----+----------+
|region 0| ... | region n |
+--/---\-+------+----------+
/ \
+-+v+------v-------+-+-+-+
| | | bitmap | | | |
+-+-+--------------+-+-+-+
It introduces the interfaces to manage dmem pages that include:
- dmem_region_register(), it registers the reserved memory to the
dmem management system
- dmem_alloc_init(), initiate dmem allocator, note the page size the
allocator used isn't the same thing with the alignment used to
reserve dmem memory
- dmem_alloc_pages_vma() and dmem_free_pages() are the interfaces
allocating and freeing dmem memory, multiple pages can be allocated
at one time, but it should be power of two
Signed-off-by: Xiao Guangrong <gloryxiao@xxxxxxxxxxx>
Signed-off-by: Yulei Zhang <yuleixzhang@xxxxxxxxxxx>
---
include/linux/dmem.h | 3 +
mm/dmem.c | 674 +++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 677 insertions(+)
diff --git a/include/linux/dmem.h b/include/linux/dmem.h
index 5049322..476a82e 100644
--- a/include/linux/dmem.h
+++ b/include/linux/dmem.h
@@ -7,6 +7,9 @@
void dmem_init(void);
int dmem_region_register(int node, phys_addr_t start, phys_addr_t end);
+int dmem_alloc_init(unsigned long dpage_shift);
+void dmem_alloc_uinit(void);
+
#else
static inline int dmem_reserve_init(void)
{
diff --git a/mm/dmem.c b/mm/dmem.c
index b5fb4f1..a77a064 100644
--- a/mm/dmem.c
+++ b/mm/dmem.c
@@ -91,11 +91,38 @@ struct dmem_pool {
.lock = __MUTEX_INITIALIZER(dmem_pool.lock),
};
+#define DMEM_PAGE_SIZE (1UL << dmem_pool.dpage_shift)
+#define DMEM_PAGE_UP(x) phys_to_dpage(((x) + DMEM_PAGE_SIZE - 1))
+#define DMEM_PAGE_DOWN(x) phys_to_dpage(x)
+
+#define dpage_to_phys(_dpage) \
+ ((_dpage) << dmem_pool.dpage_shift)
+#define phys_to_dpage(_addr) \
+ ((_addr) >> dmem_pool.dpage_shift)
+
+#define dpage_to_pfn(_dpage) \
+ (__phys_to_pfn(dpage_to_phys(_dpage)))
+#define pfn_to_dpage(_pfn) \
+ (phys_to_dpage(__pfn_to_phys(_pfn)))
+
+#define dnode_to_nid(_dnode) \
+ ((_dnode) - dmem_pool.nodes)
+#define nid_to_dnode(nid) \
+ (&dmem_pool.nodes[nid])
+
#define for_each_dmem_node(_dnode) \
for (_dnode = dmem_pool.nodes; \
_dnode < dmem_pool.nodes + ARRAY_SIZE(dmem_pool.nodes); \
_dnode++)
+#define for_each_dmem_region(_dnode, _dregion) \
+ list_for_each_entry(_dregion, &(_dnode)->regions, node)
+
+static inline int *dmem_nodelist(int nid)
+{
+ return nid_to_dnode(nid)->nodelist;
+}
+
void __init dmem_init(void)
{
struct dmem_node *dnode;
@@ -135,3 +162,650 @@ int dmem_region_register(int node, phys_addr_t start, phys_addr_t end)
return 0;
}
+#define PENALTY_FOR_DMEM_SHARED_NODE (1)
+
+static int dmem_nodeload[MAX_NUMNODES] __initdata;
+
+/* Evaluate penalty for each dmem node */
+static int __init dmem_evaluate_node(int local, int node)
+{
+ int penalty;
+
+ /* Use the distance array to find the distance */
+ penalty = node_distance(local, node);
+
+ /* Penalize nodes under us ("prefer the next node") */
+ penalty += (node < local);
+
+ /* Give preference to headless and unused nodes */
+ if (!cpumask_empty(cpumask_of_node(node)))
+ penalty += PENALTY_FOR_NODE_WITH_CPUS;
+
+ /* Penalize dmem-node shared with kernel */
+ if (node_state(node, N_MEMORY))
+ penalty += PENALTY_FOR_DMEM_SHARED_NODE;
+
+ /* Slight preference for less loaded node */
+ penalty *= (nr_online_nodes * MAX_NUMNODES);
+
+ penalty += dmem_nodeload[node];
+
+ return penalty;
+}
+
+static int __init find_next_dmem_node(int local, nodemask_t *used_nodes)
+{
+ struct dmem_node *dnode;
+ int node, best_node = NUMA_NO_NODE;
+ int penalty, min_penalty = INT_MAX;
+
+ /* Invalid node is not suitable to call node_distance */
+ if (!node_state(local, N_POSSIBLE))
+ return NUMA_NO_NODE;
+
+ /* Use the local node if we haven't already */
+ if (!node_isset(local, *used_nodes)) {
+ node_set(local, *used_nodes);
+ return local;
+ }
+
+ for_each_dmem_node(dnode) {
+ if (list_empty(&dnode->regions))
+ continue;
+
+ node = dnode_to_nid(dnode);
+
+ /* Don't want a node to appear more than once */
+ if (node_isset(node, *used_nodes))
+ continue;
+
+ penalty = dmem_evaluate_node(local, node);
+
+ if (penalty < min_penalty) {
+ min_penalty = penalty;
+ best_node = node;
+ }
+ }
+
+ if (best_node >= 0)
+ node_set(best_node, *used_nodes);
+
+ return best_node;
+}
+
+static int __init dmem_node_init(struct dmem_node *dnode)
+{
+ int *nodelist;
+ nodemask_t used_nodes;
+ int local, node, prev;
+ int load;
+ int i = 0;
+
+ nodelist = dnode->nodelist;
+ nodes_clear(used_nodes);
+ local = dnode_to_nid(dnode);
+ prev = local;
+ load = nr_online_nodes;
+
+ while ((node = find_next_dmem_node(local, &used_nodes)) >= 0) {
+ /*
+ * We don't want to pressure a particular node.
+ * So adding penalty to the first node in same
+ * distance group to make it round-robin.
+ */
+ if (node_distance(local, node) != node_distance(local, prev))
+ dmem_nodeload[node] = load;
+
+ nodelist[i++] = prev = node;
+ load--;
+ }
+
+ return 0;
+}
+
+static void __init dmem_region_uinit(struct dmem_region *dregion)
+{
+ unsigned long nr_pages, size, *bitmap = dregion->error_bitmap;
+
+ if (!bitmap)
+ return;
+
+ nr_pages = __phys_to_pfn(dregion->reserved_end_addr)
+ - __phys_to_pfn(dregion->reserved_start_addr);
+
+ WARN_ON(!nr_pages);
+
+ size = BITS_TO_LONGS(nr_pages) * sizeof(long);
+ if (size > sizeof(dregion->static_bitmap))
+ kfree(bitmap);
+ dregion->error_bitmap = NULL;
+}
+
+/*
+ * we only stop allocator to use the reserved page and do not
+ * reture pages back if anything goes wrong
+ */
+static void __init dmem_uinit(void)
+{
+ struct dmem_region *dregion, *dr;
+ struct dmem_node *dnode;
+
+ for_each_dmem_node(dnode) {
+ dnode->nodelist[0] = NUMA_NO_NODE;
+ list_for_each_entry_safe(dregion, dr, &dnode->regions, node) {
+ dmem_region_uinit(dregion);
+ dregion->reserved_start_addr =
+ dregion->reserved_end_addr = 0;
+ list_del(&dregion->node);
+ }
+ }
+
+ dmem_pool.region_num = 0;
+ dmem_pool.registered_pages = 0;
+}
+
+static int __init dmem_region_init(struct dmem_region *dregion)
+{
+ unsigned long *bitmap, size, nr_pages;
+
+ nr_pages = __phys_to_pfn(dregion->reserved_end_addr)
+ - __phys_to_pfn(dregion->reserved_start_addr);
+
+ size = BITS_TO_LONGS(nr_pages) * sizeof(long);
+ if (size <= sizeof(dregion->static_error_bitmap)) {
+ bitmap = &dregion->static_error_bitmap;
+ } else {
+ bitmap = kzalloc(size, GFP_KERNEL);
+ if (!bitmap)
+ return -ENOMEM;
+ }
+ dregion->error_bitmap = bitmap;
+ return 0;
+}
+
+/*
+ * dmem memory is not 'struct page' backend, i.e, the kernel threats
+ * it as invalid pfn
+ */
+static int __init dmem_check_region(struct dmem_region *dregion)
+{
+ unsigned long pfn;
+
+ for (pfn = __phys_to_pfn(dregion->reserved_start_addr);
+ pfn < __phys_to_pfn(dregion->reserved_end_addr); pfn++) {
+ if (!WARN_ON(pfn_valid(pfn)))
+ continue;
+
+ pr_err("dmem: check pfn %#lx failed, its memory was not properly reserved\n",
+ pfn);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int __init dmem_late_init(void)
+{
+ struct dmem_region *dregion;
+ struct dmem_node *dnode;
+ int ret;
+
+ for_each_dmem_node(dnode) {
+ dmem_node_init(dnode);
+
+ for_each_dmem_region(dnode, dregion) {
+ ret = dmem_region_init(dregion);
+ if (ret)
+ goto exit;
+ ret = dmem_check_region(dregion);
+ if (ret)
+ goto exit;
+ }
+ }
+ return ret;
+exit:
+ dmem_uinit();
+ return ret;
+}
+late_initcall(dmem_late_init);
+
+static int dmem_alloc_region_init(struct dmem_region *dregion,
+ unsigned long *dpages)
+{
+ unsigned long start, end, *bitmap, size;
+
+ start = DMEM_PAGE_UP(dregion->reserved_start_addr);
+ end = DMEM_PAGE_DOWN(dregion->reserved_end_addr);
+
+ *dpages = end - start;
+ if (!*dpages)
+ return 0;
+
+ size = BITS_TO_LONGS(*dpages) * sizeof(long);
+ if (size <= sizeof(dregion->static_bitmap))
+ bitmap = &dregion->static_bitmap;
+ else {
+ bitmap = kzalloc(size, GFP_KERNEL);
+ if (!bitmap)
+ return -ENOMEM;
+ }
+
+ dregion->bitmap = bitmap;
+ dregion->next_free_pos = 0;
+ dregion->dpage_start_pfn = start;
+ dregion->dpage_end_pfn = end;
+
+ dmem_pool.unaligned_pages += __phys_to_pfn((dpage_to_phys(start)
+ - dregion->reserved_start_addr));
+ dmem_pool.unaligned_pages += __phys_to_pfn(dregion->reserved_end_addr
+ - dpage_to_phys(end));
+ return 0;
+}
+
+static bool dmem_dpage_is_error(struct dmem_region *dregion, phys_addr_t dpage)
+{
+ unsigned long valid_pages;
+ unsigned long pos_pfn, pos_offset;
+ unsigned long pages_per_dpage = DMEM_PAGE_SIZE >> PAGE_SHIFT;
+ phys_addr_t reserved_start_pfn;
+
+ reserved_start_pfn = __phys_to_pfn(dregion->reserved_start_addr);
+ valid_pages = dpage_to_pfn(dregion->dpage_end_pfn) - reserved_start_pfn;
+
+ pos_offset = dpage_to_pfn(dpage) - reserved_start_pfn;
+ pos_pfn = find_next_bit(dregion->error_bitmap, valid_pages, pos_offset);
+ if (pos_pfn < pos_offset + pages_per_dpage)
+ return true;
+ return false;
+}
+
+static unsigned long
+dmem_alloc_bitmap_clear(struct dmem_region *dregion, phys_addr_t dpage,
+ unsigned int dpages_nr)
+{
+ u64 pos = dpage - dregion->dpage_start_pfn;
+ unsigned int i;
+ unsigned long err_num = 0;
+
+ for (i = 0; i < dpages_nr; i++) {
+ if (dmem_dpage_is_error(dregion, dpage + i)) {
+ WARN_ON(!test_bit(pos + i, dregion->bitmap));
+ err_num++;
+ } else {
+ WARN_ON(!__test_and_clear_bit(pos + i,
+ dregion->bitmap));
+ }
+ }
+ return err_num;
+}
+
+/* set or clear corresponding bit on allocation bitmap based on error bitmap */
+static unsigned long dregion_alloc_bitmap_set_clear(struct dmem_region *dregion,
+ bool set)
+{
+ unsigned long pos_pfn, pos_offset;
+ unsigned long valid_pages, mce_dpages = 0;
+ phys_addr_t dpage, reserved_start_pfn;
+
+ reserved_start_pfn = __phys_to_pfn(dregion->reserved_start_addr);
+
+ valid_pages = dpage_to_pfn(dregion->dpage_end_pfn) - reserved_start_pfn;
+ pos_offset = dpage_to_pfn(dregion->dpage_start_pfn)
+ - reserved_start_pfn;
+try_set:
+ pos_pfn = find_next_bit(dregion->error_bitmap, valid_pages, pos_offset);
+
+ if (pos_pfn >= valid_pages)
+ return mce_dpages;
+ mce_dpages++;
+ dpage = pfn_to_dpage(pos_pfn + reserved_start_pfn);
+ if (set)
+ WARN_ON(__test_and_set_bit(dpage - dregion->dpage_start_pfn,
+ dregion->bitmap));
+ else
+ WARN_ON(!__test_and_clear_bit(dpage - dregion->dpage_start_pfn,
+ dregion->bitmap));
+ pos_offset = dpage_to_pfn(dpage + 1) - reserved_start_pfn;
+ goto try_set;
+}
+
+static void dmem_uinit_check_alloc_bitmap(struct dmem_region *dregion)
+{
+ unsigned long dpages, size;
+
+ dregion_alloc_bitmap_set_clear(dregion, false);
+
+ dpages = dregion->dpage_end_pfn - dregion->dpage_start_pfn;
+ size = BITS_TO_LONGS(dpages) * sizeof(long);
+ WARN_ON(!bitmap_empty(dregion->bitmap, size * BITS_PER_BYTE));
+}
+
+static void dmem_alloc_region_uinit(struct dmem_region *dregion)
+{
+ unsigned long dpages, size, *bitmap = dregion->bitmap;
+
+ if (!bitmap)
+ return;
+
+ dpages = dregion->dpage_end_pfn - dregion->dpage_start_pfn;
+ WARN_ON(!dpages);
+
+ dmem_uinit_check_alloc_bitmap(dregion);
+
+ size = BITS_TO_LONGS(dpages) * sizeof(long);
+ if (size > sizeof(dregion->static_bitmap))
+ kfree(bitmap);
+ dregion->bitmap = NULL;
+}
+
+static void __dmem_alloc_uinit(void)
+{
+ struct dmem_node *dnode;
+ struct dmem_region *dregion;
+
+ if (!dmem_pool.dpage_shift)
+ return;
+
+ dmem_pool.unaligned_pages = 0;
+
+ for_each_dmem_node(dnode) {
+ for_each_dmem_region(dnode, dregion)
+ dmem_alloc_region_uinit(dregion);
+
+ dnode->total_dpages = dnode->free_dpages = 0;
+ }
+
+ dmem_pool.dpage_shift = 0;
+ dmem_pool.total_dpages = dmem_pool.free_dpages = 0;
+}
+
+static void dnode_count_free_dpages(struct dmem_node *dnode, long dpages)
+{
+ dnode->free_dpages += dpages;
+ dmem_pool.free_dpages += dpages;
+}
+
+/*
+ * uninitialize dmem allocator
+ *
+ * all dpages should be freed before calling it
+ */
+void dmem_alloc_uinit(void)
+{
+ mutex_lock(&dmem_pool.lock);
+ if (!--dmem_pool.user_count)
+ __dmem_alloc_uinit();
+ mutex_unlock(&dmem_pool.lock);
+}
+EXPORT_SYMBOL(dmem_alloc_uinit);
+
+/*
+ * initialize dmem allocator
+ * @dpage_shift: the shift bits of dmem page size used to manange
+ * dmem memory, it should be CPU's nature page size at least
+ *
+ * Note: the page size the allocator used isn't the same thing with
+ * the alignment used to reserve dmem memory
+ */
+int dmem_alloc_init(unsigned long dpage_shift)
+{
+ struct dmem_node *dnode;
+ struct dmem_region *dregion;
+ unsigned long dpages;
+ int ret = 0;
+
+ if (dpage_shift < PAGE_SHIFT)
+ return -EINVAL;
+
+ mutex_lock(&dmem_pool.lock);
+
+ if (dmem_pool.dpage_shift) {
+ /*
+ * double init on the same page size is okay
+ * to make the unit tests happy
+ */
+ if (dmem_pool.dpage_shift != dpage_shift)
+ ret = -EBUSY;
+
+ goto exit;
+ }
+
+ dmem_pool.dpage_shift = dpage_shift;
+
+ for_each_dmem_node(dnode) {
+ for_each_dmem_region(dnode, dregion) {
+ ret = dmem_alloc_region_init(dregion, &dpages);
+ if (ret < 0) {
+ __dmem_alloc_uinit();
+ goto exit;
+ }
+
+ dnode_count_free_dpages(dnode, dpages);
+ }
+ dnode->total_dpages = dnode->free_dpages;
+ }
+
+ dmem_pool.total_dpages = dmem_pool.free_dpages;
+
+ if (dmem_pool.unaligned_pages && !ret)
+ pr_warn("dmem: %llu pages are wasted due to alignment\n",
+ (unsigned long long)dmem_pool.unaligned_pages);
+exit:
+ if (!ret)
+ dmem_pool.user_count++;
+
+ mutex_unlock(&dmem_pool.lock);
+ return ret;
+}
+EXPORT_SYMBOL(dmem_alloc_init);
+
+static phys_addr_t
+dmem_alloc_region_page(struct dmem_region *dregion, unsigned int try_max,
+ unsigned int *result_nr)
+{
+ unsigned long pos, dpages;
+ unsigned int i;
+
+ /* no dpage is available in this region */
+ if (!dregion->bitmap)
+ return 0;
+
+ dpages = dregion->dpage_end_pfn - dregion->dpage_start_pfn;
+
+ /* no free page in this region */
+ if (dregion->next_free_pos >= dpages)
+ return 0;
+
+ pos = find_next_zero_bit(dregion->bitmap, dpages,
+ dregion->next_free_pos);
+ if (pos >= dpages) {
+ dregion->next_free_pos = pos;
+ return 0;
+ }
+
+ __set_bit(pos, dregion->bitmap);
+
+ /* do not go beyond the region */
+ try_max = min(try_max, (unsigned int)(dpages - pos - 1));
+ for (i = 1; i < try_max; i++)
+ if (__test_and_set_bit(pos + i, dregion->bitmap))
+ break;
+
+ *result_nr = i;
+ dregion->next_free_pos = pos + *result_nr;
+ return dpage_to_phys(dregion->dpage_start_pfn + pos);
+}
+
+/*
+ * allocate dmem pages from the nodelist
+ *
+ * @nodelist: dmem_node's nodelist
+ * @nodemask: nodemask for filtering the dmem nodelist
+ * @try_max: try to allocate @try_max dpages if possible
+ * @result_nr: allocated dpage number returned to the caller
+ *
+ * return the physical address of the first dpage allocated from dmem
+ * pool, or 0 on failure. The allocated dpage number is filled into
+ * @result_nr
+ */
+static phys_addr_t
+dmem_alloc_pages_from_nodelist(int *nodelist, nodemask_t *nodemask,
+ unsigned int try_max, unsigned int *result_nr)
+{
+ struct dmem_node *dnode;
+ struct dmem_region *dregion;
+ phys_addr_t addr = 0;
+ int node, i;
+ unsigned int local_result_nr;
+
+ WARN_ON(try_max > 1 && !result_nr);
+
+ if (!result_nr)
+ result_nr = &local_result_nr;
+
+ *result_nr = 0;
+
+ for (i = 0; !addr && i < ARRAY_SIZE(dnode->nodelist); i++) {
+ node = nodelist[i];
+
+ if (nodemask && !node_isset(node, *nodemask))
+ continue;
+
+ mutex_lock(&dmem_pool.lock);
+
+ WARN_ON(!dmem_pool.dpage_shift);
+
+ dnode = &dmem_pool.nodes[node];
+ for_each_dmem_region(dnode, dregion) {
+ addr = dmem_alloc_region_page(dregion, try_max,
+ result_nr);
+ if (addr) {
+ dnode_count_free_dpages(dnode,
+ -(long)(*result_nr));
+ break;
+ }
+ }
+
+ mutex_unlock(&dmem_pool.lock);
+ }
+ return addr;
+}
+
+/*
+ * allocate a dmem page from the dmem pool and try to allocate more
+ * continuous dpages if @try_max is not less than 1
+ *
+ * @nid: the NUMA node the dmem page got from
+ * @nodemask: nodemask for filtering the dmem nodelist
+ * @try_max: try to allocate @try_max dpages if possible
+ * @result_nr: allocated dpage number returned to the caller
+ *
+ * return the physical address of the first dpage allocated from dmem
+ * pool, or 0 on failure. The allocated dpage number is filled into
+ * @result_nr
+ */
+phys_addr_t
+dmem_alloc_pages_nodemask(int nid, nodemask_t *nodemask, unsigned int try_max,
+ unsigned int *result_nr)
+{
+ int *nodelist;
+
+ if (nid >= sizeof(ARRAY_SIZE(dmem_pool.nodes)))
+ return 0;
+
+ nodelist = dmem_nodelist(nid);
+ return dmem_alloc_pages_from_nodelist(nodelist, nodemask,
+ try_max, result_nr);
+}
+EXPORT_SYMBOL(dmem_alloc_pages_nodemask);
+
+/*
+ * dmem_alloc_pages_vma - Allocate pages for a VMA.
+ *
+ * @vma: Pointer to VMA or NULL if not available.
+ * @addr: Virtual Address of the allocation. Must be inside the VMA.
+ * @try_max: try to allocate @try_max dpages if possible
+ * @result_nr: allocated dpage number returned to the caller
+ *
+ * Return the physical address of the first dpage allocated from dmem
+ * pool, or 0 on failure. The allocated dpage number is filled into
+ * @result_nr
+ */
+phys_addr_t
+dmem_alloc_pages_vma(struct vm_area_struct *vma, unsigned long addr,
+ unsigned int try_max, unsigned int *result_nr)
+{
+ phys_addr_t phys_addr;
+ int *nl;
+ unsigned int cpuset_mems_cookie;
+
+retry_cpuset:
+ nl = dmem_nodelist(numa_node_id());
+
+ phys_addr = dmem_alloc_pages_from_nodelist(nl, NULL, try_max,
+ result_nr);
+ if (unlikely(!phys_addr && read_mems_allowed_retry(cpuset_mems_cookie)))
+ goto retry_cpuset;
+
+ return phys_addr;
+}
+EXPORT_SYMBOL(dmem_alloc_pages_vma);
+
+/*
+ * Don't need to call it in a lock.
+ * This function uses the reserved addresses those are initially registered
+ * and will not be modified at run time.
+ */
+static struct dmem_region *find_dmem_region(phys_addr_t phys_addr,
+ struct dmem_node **pdnode)
+{
+ struct dmem_node *dnode;
+ struct dmem_region *dregion;
+
+ for_each_dmem_node(dnode)
+ for_each_dmem_region(dnode, dregion) {
+ if (dregion->reserved_start_addr > phys_addr)
+ continue;
+ if (dregion->reserved_end_addr <= phys_addr)
+ continue;
+
+ *pdnode = dnode;
+ return dregion;
+ }
+
+ return NULL;
+}
+
+/*
+ * free dmem page to the dmem pool
+ * @addr: the physical addree will be freed
+ * @dpage_nr: the number of dpage to be freed
+ */
+void dmem_free_pages(phys_addr_t addr, unsigned int dpages_nr)
+{
+ struct dmem_region *dregion;
+ struct dmem_node *pdnode = NULL;
+ phys_addr_t dpage = phys_to_dpage(addr);
+ u64 pos;
+ unsigned long err_dpages;
+
+ mutex_lock(&dmem_pool.lock);
+
+ WARN_ON(!dmem_pool.dpage_shift);
+
+ dregion = find_dmem_region(addr, &pdnode);
+ WARN_ON(!dregion || !dregion->bitmap || !pdnode);
+
+ pos = dpage - dregion->dpage_start_pfn;
+ dregion->next_free_pos = min(dregion->next_free_pos, pos);
+
+ /* it is not possible to span multiple regions */
+ WARN_ON(dpage + dpages_nr - 1 >= dregion->dpage_end_pfn);
+
+ err_dpages = dmem_alloc_bitmap_clear(dregion, dpage, dpages_nr);
+
+ dnode_count_free_dpages(pdnode, dpages_nr - err_dpages);
+ mutex_unlock(&dmem_pool.lock);
+}
+EXPORT_SYMBOL(dmem_free_pages);
+
--
1.8.3.1
