1 files changed, 57 insertions, 31 deletions

diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index abd93b778a26..9e523db3bee1 100644
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c
@@ -1308,6 +1308,46 @@ static int virtio_mem_mb_unplug_any_sb_offline(struct virtio_mem *vm,
 }
 
 /*
+ * Unplug the given plugged subblocks of an online memory block.
+ *
+ * Will modify the state of the memory block.
+ */
+static int virtio_mem_mb_unplug_sb_online(struct virtio_mem *vm,
+					  unsigned long mb_id, int sb_id,
+					  int count)
+{
+	const unsigned long nr_pages = PFN_DOWN(vm->subblock_size) * count;
+	unsigned long start_pfn;
+	int rc;
+
+	start_pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) +
+			     sb_id * vm->subblock_size);
+	rc = alloc_contig_range(start_pfn, start_pfn + nr_pages,
+				MIGRATE_MOVABLE, GFP_KERNEL);
+	if (rc == -ENOMEM)
+		/* whoops, out of memory */
+		return rc;
+	if (rc)
+		return -EBUSY;
+
+	/* Mark it as fake-offline before unplugging it */
+	virtio_mem_set_fake_offline(start_pfn, nr_pages, true);
+	adjust_managed_page_count(pfn_to_page(start_pfn), -nr_pages);
+
+	/* Try to unplug the allocated memory */
+	rc = virtio_mem_mb_unplug_sb(vm, mb_id, sb_id, count);
+	if (rc) {
+		/* Return the memory to the buddy. */
+		virtio_mem_fake_online(start_pfn, nr_pages);
+		return rc;
+	}
+
+	virtio_mem_mb_set_state(vm, mb_id,
+				VIRTIO_MEM_MB_STATE_ONLINE_PARTIAL);
+	return 0;
+}
+
+/*
  * Unplug the desired number of plugged subblocks of an online memory block.
  * Will skip subblock that are busy.
  *
@@ -1321,16 +1361,21 @@ static int virtio_mem_mb_unplug_any_sb_online(struct virtio_mem *vm,
 					      unsigned long mb_id,
 					      uint64_t *nb_sb)
 {
-	const unsigned long nr_pages = PFN_DOWN(vm->subblock_size);
-	unsigned long start_pfn;
 	int rc, sb_id;
 
-	/*
-	 * TODO: To increase the performance we want to try bigger, consecutive
-	 * subblocks first before falling back to single subblocks. Also,
-	 * we should sense via something like is_mem_section_removable()
-	 * first if it makes sense to go ahead any try to allocate.
-	 */
+	/* If possible, try to unplug the complete block in one shot. */
+	if (*nb_sb >= vm->nb_sb_per_mb &&
+	    virtio_mem_mb_test_sb_plugged(vm, mb_id, 0, vm->nb_sb_per_mb)) {
+		rc = virtio_mem_mb_unplug_sb_online(vm, mb_id, 0,
+						    vm->nb_sb_per_mb);
+		if (!rc) {
+			*nb_sb -= vm->nb_sb_per_mb;
+			goto unplugged;
+		} else if (rc != -EBUSY)
+			return rc;
+	}
+
+	/* Fallback to single subblocks. */
 	for (sb_id = vm->nb_sb_per_mb - 1; sb_id >= 0 && *nb_sb; sb_id--) {
 		/* Find the next candidate subblock */
 		while (sb_id >= 0 &&
@@ -1339,34 +1384,15 @@ static int virtio_mem_mb_unplug_any_sb_online(struct virtio_mem *vm,
 		if (sb_id < 0)
 			break;
 
-		start_pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) +
-				     sb_id * vm->subblock_size);
-		rc = alloc_contig_range(start_pfn, start_pfn + nr_pages,
-					MIGRATE_MOVABLE, GFP_KERNEL);
-		if (rc == -ENOMEM)
-			/* whoops, out of memory */
-			return rc;
-		if (rc)
-			/* memory busy, we can't unplug this chunk */
+		rc = virtio_mem_mb_unplug_sb_online(vm, mb_id, sb_id, 1);
+		if (rc == -EBUSY)
 			continue;
-
-		/* Mark it as fake-offline before unplugging it */
-		virtio_mem_set_fake_offline(start_pfn, nr_pages, true);
-		adjust_managed_page_count(pfn_to_page(start_pfn), -nr_pages);
-
-		/* Try to unplug the allocated memory */
-		rc = virtio_mem_mb_unplug_sb(vm, mb_id, sb_id, 1);
-		if (rc) {
-			/* Return the memory to the buddy. */
-			virtio_mem_fake_online(start_pfn, nr_pages);
+		else if (rc)
 			return rc;
-		}
-
-		virtio_mem_mb_set_state(vm, mb_id,
-					VIRTIO_MEM_MB_STATE_ONLINE_PARTIAL);
 		*nb_sb -= 1;
 	}
 
+unplugged:
 	/*
 	 * Once all subblocks of a memory block were unplugged, offline and
 	 * remove it. This will usually not fail, as no memory is in use