LKML Summary Podcast

Audio: http://media.libsyn.com/media/jcm/linux_kernel_podcast_20090715.mp3

For Wednesday, July 15th, 2009, I’m Jon Masters with a summary of today’s LKML traffic.

In today’s issue: Ceph, headers, MM, and unused symbols.

Ceph. Sage Weil posted version 0.10 of the “Ceph” distributed filesystem client. Apparently, this latest version fixes a number of bugs since the previous 0.9 posting. Sage asks “what [people would] like to see for this to be merged into fs/?”.

Headers. Michal Simek and Arnd Bergmann had a discussion concerning asm-generic pgtable.h and the belief (of Michal Simek) that this could be simplified as there a lot of functions shared by all architectures. Later, Arnd followed up, suggesting that he had previously missed the commonality of the pgtable.h implementations, and provided a patch with a common version.

MM. Ben Herrenschmidt posted concerning new 64-bit “BookE” powerpc systems. These “embedded-like” systems use software-assisted page table management like their 32-bit cousins (this author worked heavily on 32-bit PowerPC 4xx TLB management code back in the day) but also have a capability for a special form of multi-level PTE in which the RPN of an individual PTE is actually an array of PTEs from which a TLB can automatically create entries. This implementation necessitates the presence of the virtual address in the TLB freeing code, so Ben’s patch updates all architectures in the process of adding this additional information to all forms of these functions.

Separately but also on an MM note, Mel Gorman posted a series of MM patches. These included warning when a page is freed but has PG_mlocked set, ensuring that OOM killed tasks set TIF_MEMDIE and thus exit the page allocator, and a resend of a patch covered previously in this podcast, which will suppress warnings about order >= MAX_ORDER page allocations where the caller knows how to handle these and has set __GFP_NOWARN.

Unused symbols. Robert P. J. Day posted asking if there was now any value in retaining the EXPORT_UNUSED_SYMBOL and EXPORT_UNUSED_SYMBOL_GPL macros, intended to annotate exported symbols that should not be used by modules in the longer term, and scheduled previously for feature removal from the kernel way back when in the 2.6.19 timeframe. At this point, there is only one actual in-kernel user of these macros (libfs – simple_prepare_write).

In today’s miscellaneous items: The ext4 memory leak reported on Wednesday by kmemleak on a system under the control of Alexey Fisher seems to have been fixed by a patch from Aneesh Kumar, some ide-tape fixes (Borislav Petkov), a patch to the connector code (Mike Frysinger) such that it actually explicitly uses struct cn_msg everywhere (as is documented) rather than void pointers, asynchronous device actions (asynchronous power management) patches (Zhang Rui), ptrace regsets support for S+Core (Liqin Chen), a second version of the patch implementation gmtime and localtime from yesterday, following feedback from Andrew Morton (Zhao Lei), some DRM fixes from Dave Airlie, and an SMI workaround in pit_expect_msb for certain systems vulnerable to ill-timed SMIs triggering an incorrect pit calibration and CPU MHz value (Wei Chong Tan).

Finally today, Jeremy Fitzhardinge wondered aloud about the plumbing of splice into the Linux network stack. He is specifically interested in carrying pages granted by one Xen domain through the Linux network stack without copying, and asked Jens for his opinions on using splice to implement this. One complication he saw was that he does not easily have a struct page available for the management of the splicing, but thinks this can be solved.

In today’s announcements: Jesper Dangaard Brouer posted to announce that he has achieved 10Gbit/s bidirectional routing on standard hardware running Linux, using pre-release versions of Intel’s 82559 chip. Summing the totals for ingress and egress across several interfaces, Jesper is actually handling a total of around 38 Gbit/s. He plans to give a talk at LinuxCon on the subject of 10Gbit/s routing on Linux systems. Also in today’s announcements, version 2.16 of the util-linux-ng from Karel Zak, and version 1.6.4.rc1 of the Git SCM was posted by Junio C Hamano.

The latest kernel release was 2.6.31-rc3, which was released by Linus over the weekend. Current reports suggest stability is improving over previous RCs.

Andrew Morton posted an mm-of-the-moment for 2009-07-15-20-57, which contains a number of patches against 2.6.31-rc3.

Stephen Rothwell posted a linux-next tree for July 15th. Since Tuesday, the usb and its dependent staging tree were undropped, the tree still fails to build in an allyesconfig build configuration for powerpc, and two additional build failures necessitated older versions of the pci and dwmw2-iommu trees. The total sub-tree count in the current linux-next compose remains steady at a total of 132 trees.

That’s a summary of today’s LKML traffic. For further information visit kernel.org. I’m Jon Masters.