LKML Summary Podcast

Audio: COMING SOON

For Tuesday, September 22nd, 2009, I’m Jon Masters with a summary of today’s LKML traffic.

In today’s issue: Fanotify, and modules.

NOTE: Several kernel hackers were at or en route to LPC (Linux Plumbers Conference) and so the traffic volumes were affected.

Fanotify. Fanotify is a new framework originally authored by Eric Paris (thanks a lot!) in order to help “anti”-malware vendors intercept and authorize certain file operations on the fly, using a generic interface. But fanotify is intended to be useful for other purposes, as Jamie Lokier pointed out (at the same time as re-affirming his total lack of interest in malware scanning uses thereof) was his reason for “sticking his oar” in recently. He is keen to see non-malware uses (improved inotify and other userspace indexing services, such as update) work out right. Davie Libenzi wondered whether, since the malware scanners generally favor “hacking” the syscall table, Linux should just provide a “non racy” mechanism for interrupting and monitoring system calls as some kind of ptrace-on-steriods perhaps. Argument continued on this and many other topics, including whether literal pathnames were important or whether on-access scanning tools should have to look them up if they care, and on whether ioctls or “idiotic packet interfaces” like netlink were best.

Modules. Alan Jenkins posted some module patches intending to speed up symbol resolution during load. The current Linux module implementation has modprobe (or perhaps insmod, if modprobe is not being used) simply load an ELF image containing a number of sections that the kernel will then link itself (in contrast to the old days, when it was all linked in userspace). Alan’s patches sort the tables of builtin kernel symbols so that the module loader can resolve against them using a standard binary search at load time. Using these patches, Alan has elimated 20% of the CPU cycles and 0.3 seconds of real time for a system boot on his EeePC 701 system. Kudos to Alan, once again.

In today’s pull requests: some kmemcheck updates from Vegard Nossum, some tracing/workqueue fixes from Anton Blanchard, another round of RFC patch from Zhang Rui implementing the ALS (”Ambient Light Sensor”) sysfs class driver, version 4 of his “compcache” compressed swap patches from Nitin Gupta, some performance counters (”performance events”) fixes from Ingo Molnar, some timer updates from Thomas Gleixner, some tracing/kprobes updates from Frederic Weisbecker, some s390 patches from Martin Schwidefsky, some sound patches from Takashi Iwai, and some regulator patches for 2.6.32 from Liam Girdwood.

In today’s miscellaneous items: some performance events fixes for powerpc from Paul Mackerras, an endorsement for a dedicated tracing mailing list from Li Zefan and Avi Kivity (both in reply to Steven Rostedt, Avi kicking things off with an initial question to boot), some futex cleanups (and also a race fix) from Darren Hart, version 5 of the RFC cpuidle POWER infrastructure patches intended to allow flexible management of idle policy from Arun R Bharadwaj, a “philosophical” question concerning which of two uaccess.h (linux or asm) headers should be included from Robert P. J. Day, some S+Core patches from Liqin Chen (including header files in that architecture’s linker script), an MCE error injection fix in the face of real errors from Huang Ying, a patch implementing a new “kcoredump” module that uses kprobes to perform a kernel “core dump” anywhere within the kernel (not as in the existing implementation of /proc/kcore) from Hui Zhu, another RFC patch implementing a SCHED_EDF (”Earliest Deadline First”) scheduler from “Raistlin”, version 3 of his RFC SLBQ on memoryless node configurations patches from Mel Gorman, some further linker script cleanup patches (facilitating ksplice integration) from Tim Abbott, an admission that once all other users of CONFIG_PARAVIRT are gone even lguest may not be enough to keep it around(!) from Rusty Russell, and patches containing the latest implementation of the Ceph distributed filesystem client from Sage Weil.

The latest kernel release was 2.6.31.

Shaohua Li reported a regression in page writeback statistics on a test system featuring 12 disks in kernels after a specific commit, but could not figure out an immediate fix for the issue, and so sought further comments. Xiaotian Feng reported a problem running “startx” to start an X session on the latest git tree, attributing it to an issue with KMS on a Fedora 11 system (to which Peter Zijlstra suggested either disabling KMS or updating the Fedora system). Darren Hart reported that he is hitting a repeating BUG on boot on his Thinkpad T60p when running the latest 2.6.31-rt11 preempt-rt kernel (which Clark Williams thinks he saw previously but thought was fixed now – and so Clark requested that Darren send him his kconfig to verify).

Stephen Rothwell announced that there would also not be a linux-next release for September 22nd – he was still feeling under the weather.

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