You May Want To Wait On Trying Out The Linux 4.2 Kernel

Written by Michael Larabel in Linux Kernel on 6 July 2015 at 01:19 PM EDT. 12 Comments
If you're a Linux enthusiast that's a habitual upgrader of the Linux kernel, you may want to hold off a few days on trying out the Linux 4.2 development kernel. For several systems, I've seen nothing but kernel panics the past few days when riding the mainline Linux kernel Git.

With the automated test farm that's powering and other Phoronix tests, it's nothing abnormal when early in a Linux kernel development cycle to occasionally see a system or two run into troubles -- most often a kernel panic or unexpected reboot. However, towards the end of the Linux 4.2 kernel merge window it's been worse than usual -- then again, this is one of the biggest kernel updates ever.

Since Thursday/Friday I've run into multiple systems hitting kernel problems when freshly booting the system with the latest daily kernel Git code. As of this morning with 4.2-rc1, several of the systems still are not playing nicely with this new kernel code. The systems that remain problematic as of this morning are a dual Opteron 2384, A10-7850K Kaveri, Athlon II X3 425, Celeron N2820 NUC, and Core i5 520M. On boot they run into show-stopping kernel panics.

This will likely get all cleared up in the next few days, but just take this as a word of caution if you've been wanting to try out the Linux 4.2 code in order to try out the many new Linux kernel features.

Before anyone asks, no, unfortunately it's not much of an option to do the bisecting of the regressions given the affected systems are rather slow, and while PTS has support for auto-bisecting and can withstand preserving states across reboots, it will hang on the faulty kernel revisions and require manual intervention to recover. Likewise, there's no upstream bug reports for these bugs given that it's enough of a burden already maintaining these systems and it's already costing hundreds of dollars per month in expenses while running this ad-free performance tracking site as a public resource. With the common 100 hour work week, there's also a lack of time for carrying out manual tasks/testing for bug report follow-ups, etc. If you wish to see this policy change, please consider sponsoring the work via PayPal tips, Bitcoin, or by subscribing to Phoronix Premium, etc. Thanks and stay tuned for updates on the Linux 4.2 testing.
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Michael Larabel

Michael Larabel is the principal author of and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via

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