Upon rebooting my system, the boot process freezes, saying it's unable to mount at least one of my btrfs partitions. This happens both in my desktop and laptop systems. On the desktop, attempting to mount the said partition manually froze the system. Upon checking dmesg, I found this (please excuse any typos, as I'm typing it on a laptop while looking at the output on my desktop's monitor): mar 29 15:03:37 pcname systemd[1]: home.mount mount process still around after mar 29 15:03:37 SIGKILL. Ignoring. pcname systemd[1]: Failed to mount /home. -- Subject: Unit home.mount has failed -- Defined-By: systemd -- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel -- -- Unit home.mount has failed. -- --The result is failed. I have the same issue happening on my laptop. Except that the unmountable partition is /var instead. As I stated previously, both systems run on btrfs partitions. Also, both of them run Arch Linux. The laptop has systemd 2.18, while the desktop has systemd 2.18-2 installed. Both machines have version 3.19-2 of the Linux kernel installed.
There is a bug in BTRFs that could trigger when a systems isn't shut down properly. This leads to a deadlock with the log replay. The proper fix is here: https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/fs/btrfs?id=9c4f61f01d269815bb7c37be3ede59c5587747c6 Else you can clear the log with btrfs-zero-log You should at least check it out.
Closing as this appears to have been a kernel bug.
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