Re: [syzbot] [btrfs?] kernel BUG in btrfs_qgroup_inherit

[Edward Adam Davis]

#syz test

diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 9e2b53e90dcb..ac5380520152 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -3289,10 +3289,6 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, u64 srcid,
 	if (!btrfs_qgroup_enabled(fs_info))
 		return 0;
 
-	prealloc = kzalloc(sizeof(*prealloc), GFP_NOFS);
-	if (!prealloc)
-		return -ENOMEM;
-
 	/*
 	 * There are only two callers of this function.
 	 *
@@ -3388,6 +3384,12 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, u64 srcid,
 		}
 	}
 
+	prealloc = kzalloc(sizeof(*prealloc), GFP_NOFS);
+	if (!prealloc) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
 	spin_lock(&fs_info->qgroup_lock);
 
 	dstgroup = add_qgroup_rb(fs_info, prealloc, objectid);