LKML Summary Podcast

Audio: http://media.libsyn.com/media/jcm/linux_kernel_podcast_20090625.mp3

For Thursday, June 25th 2009, I’m Jon Masters with a summary of today’s LKML traffic.

In today’s issue: Futexes, kmemleak, and mixed endianness.

Futexes. Thomas Gleixner came to Linus, cap in hand, apologizing for the mixup over correct usage of get_user_pages (the forth argument is actually a number of pages and not a straight length – Peter Zjilstra previously posted fixes to the documentation of this function to avoid similar future mishaps). Thomas joked that he’s running out of brown paper bags to throwup into, and so is declaring all future futex bugs fixed by definition and thus features.

Kmemleak. Dave Jones reported a lot of (likely false positive) kmemleak reports on his latest Fedora (rawhide) test kernels. Catalin Marinas followed up with some suggestions for kernel config changes and a noise reducing patch, enabling task stacks scanning by default, which Dave confirmed he had similarly done for his test kernels in response to the noise.

Mixed endianness. Andrew Paprocki wondered aloud whether it is really possible to mix endianness within a process on IA64. According to the documentation which Andrew cited, IA64 uses a .be bit in the PSR (Processor Status Register) to switch from one mode to another, although other (kernel) documentation says that this is not preserved by the kernel upon return from system calls – so the system is always returned to little endian mode following a system call. The question was whether it was practical to wrap system calls with a switch back from little endian to big endian once again. Nobody has answered him, yet.

Miscellaneous updates include: cpufreq lockdep fixes (Venkatesh Pallipadi), some fixes to avoid various races in irqfd/eventfd (Gregory Haskins), the 12th iteration of the per-bdi writeback flusher threads (Jens Axboe), various IDE fixes (David Miller, many by way of the previous maintainer), and a TTM page pool allocator patch for allocating e.g. AGP buffers for graphic from Jerome Glisse, which looks to be more of an RFC at this point. Steven Rostedt ACKed the general availability of the ring_buffer independently of tracing code following its use by this author’s hwlat patches.

Finally today, Robert P J Day announced that he is running his existing cleanup scripts against the kernel CONFIG options, looking for orphans. He says that he has found a number that are mentioned in a Kconfig file but not in fact used in the kernel tree at this point.

In today’s announcements: Ksplice for Ubuntu 9.04 Jaunty. Local Cambridge resident and Ksplice, Inc. founder Jeff Arnold announced that his company has begun offering updates for Ubuntu 9.04. For those just tuning in, ksplice is a dynamic kernel patching infrastructure allowing for “rebootless kernel updates”. It can handle ABI changes, structure modifications, all the kinds of things one might expect, and it doesn’t (necessarily) require a special kernel to begin with since it does all of its work in loadable modules under a kernel stop_machine context. Ksplice includes a lot of very interesting technology and the “Uptrack” service for Ubuntu is aimed to generate interest in their other commercial rebootless update offerings for the “Enterprise” distros. usbutils 0.84. Greg Kroah-Hartman announced version 0.84 of usbutils. This release fixes several bugs.

The latest kernel release is 2.6.31-rc1, which was released by Linus on Wednesday evening PDT.

Stephen Rothwell posted a linux-next tree for June 25th. Since Wednesday, his fixes tree contains several commits, the tree still fails to build in an allyesconfig build configuration on PowerPC, and a number of conflicts and build failures were removed in time for 2.6.31-rc1.

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