LKML Summary Podcast

AUDIO: http://media.libsyn.com/media/jcm/linux_kernel_podcast_20091109_corrected.mp3

For Monday, November 9th, 2009, I’m Jon Masters with a summary of today’s LKML traffic.

In today’s issue: CFS, Cisco VPN, Fsck, Resume, and Too Many Signals.

CORRECTED: Indeed, I screwed this up by mixing up two patches. The following is about CFS task limit scheduling, not CFQ, patches for which I was reading about at the time also.

CFS Hard Limits. Bharata B. Rao posted version 3 of his CFS Hard Limits patch series. This is intended to allow for configurable hard limits on CPU used by task groups.

Cisco VPN. Mariusz Smykula, noting that this was “not yours problem” posted to let everyone know that kernels after 2.6.29 seem to break support for the proprietary Cisco VPN client, apparently needed on some “certified” systems that by implication cannot run vpnc or similar. The posting included a variety of links to users discussing the issues, though it does seem unlikely that the kernel community will rush to help Cisco with proprietary software.

Fsck. Ted T’so pointer out (in a thread entitled “document conditions when reliable operation is possible”) that “as the ext3 authors have stated many times over the years, you still need to run fsck periodically anyway.” This lead David Lang to question where that documentation was, to which Ted replied that it was in the LKML archives. Apparently, the lack of documentation that explicitly mentions this was a contributing factor in “SUSE11-or-so” ceasing to perform periodic fscks on its own because Pavel Machek could not find sufficient documentation justifying this when the decision was made.

Resume. Rafael J. Wysocki posted a request for help diagnosing a problem with the suspend and resume code in 2.6.32-rc. For several days, he has been trying to debug resume problems (that obviously might be suspend problems) on his Toshiba Portege R500. Apparently, it seems to be caused by leakage of preempt_count in the events kernel thread, but Rafael has never been able to capture a full oops message, so that is based only upon some detective work performed using gdb and a partial trace output. He did find a commit (from himself) that upon removal would make the issue unreproducible, but he believes that commit (preparing for early/late parts to resume) simply exercises code paths that make the problem more easily triggerable. He also found an earlier commit in which the leak lead to a warning (run_workqueue) that didn’t kill the box, but might be responsible for the hard lockup seen later on. Later, he found and posted a full trace, stuck in run_workqueue.

Too many signals. Naohiro Ooiwa posted a patch to the handling of the print-fatal-signals kernel boot parameter such that sysadmins will receive a warning when RLIMIT_SIGPENDING is exceeded and can choose to enable the additional logging facility to diagnose what is really going on.

Finally today, are you feeling motivated? Mark Pith announced that his research team (at the University of Amsterdam) were researching the “motivation factors of Open Source software programmers”. He would like you to complete a short survey that won’t exceed 15 minutes in length. The link to the survey is: http://bit.ly/Survey_Developers_Motivation.

In today’s announcements: Linux 2.6.27.39 and Linux 2.6.31.6. Greg Kroah-Hartman announced the release of kernels 2.6.27.39 and 31.6. These were in review over the weekend.

LTTng 0.167. Mathieu Desnoyers announced the latest LTTng patch for 2.6.31.6, encouraging all users to upgrade to the latest .31 series kernel since it contains security fixes.

The latest kernel release is 2.6.32-rc6.

Stephen Rothwell posted a linux-next tree for Novemeber 9th. Since Friday, several trees are feeling less “angry” (they’re always “in conflict” you see, according to Katherine). The sparc tree lost its build failure, the net tree lost a conflict but gained another for which Stephen applied a patch. The wireless, pcmcia, trivial and staging trees also gained similar conflicts. The total number of subtrees in linux-next remained steady at 146 trees.

That’s a summary of today’s Linux Kernel Mailing List traffic, for further information visit www.kernel.org. I’m Jon Masters.