On 2015-12-04 05:00, Russell Coker wrote:
One of my test laptops started hanging on mounting the root filesystem. I think that it had experience an unexpected power outage prior to that which may have caused corruption.When I tried to mount the root filesystem the mount process would stick in D state, there would be no disk IO, and the computer would get hot - presumably due to kernel CPU use even though "top" didn't seem to indicate that. When I mounted the filesystem with a 4.2.0 kernel it said "The free space cache file (1103101952) is invalid, skip it" and then things worked. Now that the machine is running 4.2.0 everything is fine. I know that there are no plans to backport things to 3.16 and I don't think the Debian people are going to be very interested in this. So this message is a FYI for users, maybe consider not using the Debian/Jessie kernel for BTRFS systems.
I'd suggest extending that suggestion to:If you're not using an Enterprise distro (RHEL, SLES, CentOS, OEL), then you should probably be building your own kernel, ideally using upstream sources.
Ubuntu is notorious for picking 'stable' kernels that then fail to be marked by kernel.org as LTS, Debian picks kernels that are multiple versions old by the time they make a release, and I've heard similar from other non-enterprise distros that don't inherently make you build your own kernel. Even among ones that you have to build the kernel yourself anyway, there are issues (Gentoo for example doesn't often mark new kernels as stable, even when they are perfectly usable for pretty much everyone).
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