Use GFP_ATOMIC for allocations that are required for swap on zvols

dmu_bio_clone(), __vdev_disk_physio() and vdev_disk_io_flush() are used when doing swap to a zvol. Failing to use GFP_ATOMIC permits them to block under memory pressure, which can prevent swap operations and cause deadlocks. We use GFP_ATOMIC | __GFP_HIGH for these allocations because they are required for swap operations on zvols. Signed-off-by: Richard Yao <ryao@cs.stonybrook.edu>
ryao · Jul 3, 2013 · 8f157ab · 8f157ab
1 parent 294f680
commit 8f157ab
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Showing 2 changed files with 3 additions and 3 deletions.
diff --git a/module/zfs/dmu.c b/module/zfs/dmu.c
@@ -1059,7 +1059,7 @@ dmu_bio_clone(struct bio *bio, struct bio **bio_copy)
 		return EINVAL;
 
 	while (bio) {
-		bio_new = bio_clone(bio, GFP_NOIO);
+		bio_new = bio_clone(bio, GFP_ATOMIC | __GFP_HIGH);
 		if (bio_new == NULL) {
 			dmu_bio_put(bio_root);
 			return ENOMEM;

diff --git a/module/zfs/vdev_disk.c b/module/zfs/vdev_disk.c
@@ -543,7 +543,7 @@ __vdev_disk_physio(struct block_device *bdev, zio_t *zio, caddr_t kbuf_ptr,
 			goto retry;
 		}
 
-		dr->dr_bio[i] = bio_alloc(GFP_NOIO,
+		dr->dr_bio[i] = bio_alloc(GFP_ATOMIC | __GFP_HIGH,
 		                          bio_nr_pages(bio_ptr, bio_size));
 		if (dr->dr_bio[i] == NULL) {
 			vdev_disk_dio_free(dr);
@@ -632,7 +632,7 @@ vdev_disk_io_flush(struct block_device *bdev, zio_t *zio)
 	if (!q)
 		return ENXIO;
 
-	bio = bio_alloc(GFP_KERNEL, 0);
+	bio = bio_alloc(GFP_ATOMIC | __GFP_HIGH, 0);
 	if (!bio)
 		return ENOMEM;