LKML Summary Podcast

AUDIO: http://media.libsyn.com/media/jcm/linux_kernel_podcast_20091111.mp3

For Veterans Day (November 11th) 2009, I’m Jon Masters with a summary of today’s LKML traffic.

In today’s issue: Floppy, LZO, Resume, and Wakeup.

Floppy. Just when you thought nobody used floppy disks any more. Stephen Hemminger posted to let everyone know that “mount -o sync” support has a regression for floppy disk use cases in kernel 2.6.31. Some time between 2.6.30 and 2.6.31-rc1, the anticipated behavior of writes immediately completing and blocking until they hit the ext2-formatted disk broke and a copy followed by disk removal followed by unmount results in errors. This potentially may affect USB thumbdrive users, so has some wider relevance.

LZO. Albin Tonnerre posted version 3 of a patch series implementing generic LZO compression for kernel binary images on x86, ARM. The patches include support both for building and using these images, and their initramfses.

Resume. Rafael J. Wysocki and Linus Torvalds chimed in on Rafael’s previous posting concerning broken resume-from-suspend. After applying a patch intended to help diangose the problem, Rafael reported that errors were being generated by btusb_waker, which Linus said matched his “observation that only a few [Bluetooth] drivers seem to use workqueues, and btusb_disconnect() isn’t doing any work cancel”. Marcel Holtmann and others began discussing solutions.

Wakeup. Yinghai Lu posted version 2 of a patch intended to make doubly sure that ACPI wakeup code is located below 1M in physical memory on x86. The patch attempts to find a suitable region in the BIOS/EFI/firmwire specified “e820″ area (a table of memory mappings on such systems) and reserve it early on.

The latest kernel release is 2.6.32-rc6.

Stephen Rothwell posted a linux-next tree for Novemeber 11th. Since Tuesday, the i2c tree lost a conflict, the new tree gained a conflict, the wireless tree lost a build failure, the rr tree gained a build failure, the pcmcia tree gained a conflict, the tip tree gained a build failure, the percpu tree gained a conflict, and the usb tree also gained a conflict. The total sub-tree count is now at 148 trees, since the previous issues with pulling trees resolved.

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

AUDIO: http://media.libsyn.com/media/jcm/linux_kernel_podcast_20091110.mp3

For Tuesday, November 10th, 2009, I’m Jon Masters with a summary of today’s LKML traffic.

In today’s issue: AppArmor, Changing task UIDs, SECURITY_FILE_CAPABILITIES, and Stable tags and git workflow.

AppArmor. John Johansen posted version 3 of a 12 part patch series intended to re-implement the AppArmor security module (which was previously maintained out of tree by Novell, until it wasn’t, then seemed to die shortly after Canonical begun to support it, and now has returned in a new form in a posting from John, who is a Canonical engineer) upon the security_path hooks instead of the previous VFS hack. AppArmor is a path-based alternative to SELinux that is sometimes seen as being less complicated to setup, although this is debated. In any case, these patches seem more supportable for upstream inclusion.

Changing task UIDs. Enrico Weigelt, who is working on plan9 patches inquired as to the best way to implement plan9-style support for changing the UID of running tasks, perhaps through a new /proc entry. He then proceeded to post various replies to other threads he had not previously been involved with – amongst other things criticizing hald and dbus design, and espousing the virtues of plan9 (if only it had more users to sell us on its features?).

SECURITY_FILE_CAPABILITIES. Serge E. Hallyn posted suggesting the the Kconfig option SECURITY_FILE_CAPABILITIES be removed, specifically invalidating the case of SECURITY_FILE_CAPABILITIES=n, and meaning that such capabilities would always be enabled unless the user specified no_file_caps on system boot. The reason behind this suggestion stems from an apparent missunderstanding amonsgt a growing number of application developers that such support is always present, leading Serge to wonder if it might aswell just be by now.

Stable tags and git workflow. Ingo Molnar posted an RFC concerning stable tree git commit workflow. He noted that that previously, he would have to email (cherry pick) the specific pre-requisite dependencies for any stable patch forwarded to the stable team (or wait for an email when things didn’t apply to the stable tree), but felt that this could be optimized. So, Ingo has begun adding comments on “CC” lines in the patch indicating additional commits that should be included, e.g. “# .32.x: : “. These commits are added to a new “-stable” tag on Ingo’s -tip tree. He seeks comments.

Finally today, Chris Friesen had asked about correct use of IANA-registered ports on systems running sunrpc. Specifically, the RPC implementation as used by NFS can make use of ports that are reserved for other services, if a range has not been set aside ahead of time (and even then, it’s not optimal if you really want to run every service). But Trond Myklebust asked the obvious: “The people who are trying to run absolutely all IANA registered services on a single Linux machine that is also trying to run as an NFS client may have a problem, but then again, how many setups do you know who are trying to do that?”. The answer, one assumes, is less than one.

In today’s announcements: 2.6.31.6-rt19. Thomas Gleixner announced preempt-rt patch series release number rt19 for the 2.6.31.6 stable kernel. This was mostly a forward port to the latest stable tree, but also contains a missing pre-emption point in ksoftirqd. The patches are avaialable in the usual locations, amongst them: http://www.kernel.org/pub/linux/kernel/projects/rt.

The latest kernel release is 2.6.32-rc6.

Stephen Rothwell posted a linux-next tree for November 10th. Since Monday, there was a new sysctl tree from Eric W. Biederman that contains only the generic compat_sys_sysctl patches now that binary sysctls are going away. The net tree lost both a conflict and build failure, the wireless tree still has a build failure, and the trivial tree lost a conflict. Stephen reports the sub-tree count at 146, but that is incongruent with the new tree.

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

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.