Merge branch 'akpm' (fixes from Andrew)

Merge misc fixes from Andrew Morton.

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mqueue: sys_mq_open: do not call mnt_drop_write() if read-only
  mm/hotplug: only free wait_table if it's allocated by vmalloc
  dma-debug: update DMA debug API to better handle multiple mappings of a buffer
  dma-debug: fix locking bug in check_unmap()
  drivers/rtc/rtc-at91rm9200.c: use a variable for storing IMR
  drivers/video/ep93xx-fb.c: include <linux/io.h> for devm_ioremap()
  drivers/rtc/rtc-da9052.c: fix for rtc device registration
  mm: zone_end_pfn is too small
  poweroff: change orderly_poweroff() to use schedule_work()
  mm/hugetlb: fix total hugetlbfs pages count when using memory overcommit accouting
  printk: Provide a wake_up_klogd() off-case
  irq_work.h: fix warning when CONFIG_IRQ_WORK=n

1 files changed, 31 insertions, 14 deletions

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 5e396accd3d0..d87a17a819d0 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -862,17 +862,21 @@ static void check_unmap(struct dma_debug_entry *ref)
 	entry = bucket_find_exact(bucket, ref);
 
 	if (!entry) {
+		/* must drop lock before calling dma_mapping_error */
+		put_hash_bucket(bucket, &flags);
+
 		if (dma_mapping_error(ref->dev, ref->dev_addr)) {
 			err_printk(ref->dev, NULL,
-				   "DMA-API: device driver tries "
-				   "to free an invalid DMA memory address\n");
-			return;
+				   "DMA-API: device driver tries to free an "
+				   "invalid DMA memory address\n");
+		} else {
+			err_printk(ref->dev, NULL,
+				   "DMA-API: device driver tries to free DMA "
+				   "memory it has not allocated [device "
+				   "address=0x%016llx] [size=%llu bytes]\n",
+				   ref->dev_addr, ref->size);
 		}
-		err_printk(ref->dev, NULL, "DMA-API: device driver tries "
-			   "to free DMA memory it has not allocated "
-			   "[device address=0x%016llx] [size=%llu bytes]\n",
-			   ref->dev_addr, ref->size);
-		goto out;
+		return;
 	}
 
 	if (ref->size != entry->size) {
@@ -936,7 +940,6 @@ static void check_unmap(struct dma_debug_entry *ref)
 	hash_bucket_del(entry);
 	dma_entry_free(entry);
 
-out:
 	put_hash_bucket(bucket, &flags);
 }
 
@@ -1082,13 +1085,27 @@ void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
 	ref.dev = dev;
 	ref.dev_addr = dma_addr;
 	bucket = get_hash_bucket(&ref, &flags);
-	entry = bucket_find_exact(bucket, &ref);
 
-	if (!entry)
-		goto out;
+	list_for_each_entry(entry, &bucket->list, list) {
+		if (!exact_match(&ref, entry))
+			continue;
+
+		/*
+		 * The same physical address can be mapped multiple
+		 * times. Without a hardware IOMMU this results in the
+		 * same device addresses being put into the dma-debug
+		 * hash multiple times too. This can result in false
+		 * positives being reported. Therefore we implement a
+		 * best-fit algorithm here which updates the first entry
+		 * from the hash which fits the reference value and is
+		 * not currently listed as being checked.
+		 */
+		if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
+			entry->map_err_type = MAP_ERR_CHECKED;
+			break;
+		}
+	}
 
-	entry->map_err_type = MAP_ERR_CHECKED;
-out:
 	put_hash_bucket(bucket, &flags);
 }
 EXPORT_SYMBOL(debug_dma_mapping_error);