BTRFS 警告（设备 xxx）：交换文件不能为写时复制。为什么交换在禁用时被激活？

Question

我有 SSD。当我检查时dmesg，我看到警告并失败：

$ sudo dmesg | grep swap
[    0.085887] Spectre V1 : Mitigation: usercopy/swapgs barriers and __user pointer sanitization
[    0.429424] zswap: loaded using pool lzo/zbud
[   35.685791] systemd[1]: Activating swap /swapfile...
[   35.690098] BTRFS warning (device nvme0n1p4): swapfile must not be copy-on-write
[   35.691545] systemd[1]: swapfile.swap: Swap process exited, code=exited, status=255/EXCEPTION
[   35.691549] systemd[1]: swapfile.swap: Failed with result 'exit-code'.
[   35.691934] systemd[1]: Failed to activate swap /swapfile.
[   35.691969] systemd[1]: swap.target: Job swap.target/start failed with result 'dependency'.
[   36.112620] BTRFS warning (device nvme0n1p4): swapfile must not be copy-on-write
[   36.326045] BTRFS warning (device nvme0n1p4): swapfile must not be copy-on-write

如果我禁用交换，为什么系统会尝试激活交换？

$ cat /etc/fstab | grep swap
/swapfile                                 none            swap    sw              0       0

Answer 1

要真正禁用交换文件，我们应该这样做：

在 shell 提示符下以 root 身份执行以下命令以禁用交换文件（其中 /swapfile 是交换文件）：
swapoff -v /swapfile
从 /etc/fstab 文件中删除其条目。
删除实际文件：
rm /swapfile

https://docs.fedoraproject.org/en-US/Fedora/14/html/Storage_Administration_Guide/s2-swap-removing-file.html