LKML Summary Podcast

Audio: http://media.libsyn.com/media/jcm/linux_kernel_podcast_20090803.mp3

For Monday, August 3rd, 2009, I’m Jon Masters with a summary of today’s LKML traffic.

In today’s issue: Cacheing get_current() and get_thread_info(), kfifo, KSM, Tracing, userspace DMA, and a standard VME implementation.

Cacheing get_current() and get_thread_info() values. Linus Torvalds, upon examining some of the assembly code generated for recent kernel compiles (in particular the accessor code to read these values) decided that it was long since time to provide some form of cacheing of these values. So, Linus being Linus, he hacked up a new version of percpu_read called percpu_read_stable. The former will continue to generate code accessing the percpu variable every time it is used to retreive one of these thread related information objects, whereas the latter “stable” version allows the value to be cached if the compiler and assembler can arrange for that to be the case.

kfifo. Stefani Seibold posted an RFC patch series implementing a new “generic kernel FIFO implementation”, known as “kfifo”. According to Stefani, the current kernel FIFO API is not very widely used because it has too many constraints (there are only 13 files using it in 2.6.30 according to Stefani). Stefani views FIFOs as a kind of basic type akin to a list and so wants to remove the constraints (such as requiring a lock whether additional locking is needed or not). He implements kfifo_alloc, kfifo_free, kfifo_reset, and so forth, all using the struct kfifo type. For further information see the original list posting, or the inevitable Linux Weekly News coverage.

KSM. Kernel Shared Memory allows one to scan physical pages of memory and reconcile identical copies of data as copy on write pages. It is especially useful for virtual machines, where two independent machine images would not otherwise automatically share data pages that happened to be identical. A lot of work has recently gone into KSM, especially for obvious KVM uses. This year’s Linux Symposium featured a presentation from Andrea Arcangeli on the subject in fact. Meanwhile, Hugh Dickins has been cleaning up KSM for 2.6.32 and has posted a series of updates that he would like to apply both for the upcoming merge window, and also into Andrew’s mm-of-the-moment (mmotm). These include a number of fixes (including an endless OOM loop) and the removal of the VM_MERGEABLE_FLAGS, as well as additional tunables and documentation.

Tracing. Lai Jiangshan posted an RFC patch modification to the crash utility in order to allow it to read in-flight kernel trace buffers captured from the crash dump image. This allows tracing to, quote “act as a flight recorder” in preserving the buffers post-mortum. The work was well received by Christoph Hellwig who described it as “Nice!” (high praise indeed!). Christoph also took the opportunity to suggest that the impressive “CC” list suggested it is time for a linux-trace mailing list. Your author was greatful as always to be on the CC, although I do make an effort to read most mails send to the LKML

Userspace DMA. Leon Woestenberg mailed to ask whether it was acceptable to have a PCI device DMA-read from pages that belong to a file mmap()ed by userspace, why get_user_pages() might fail in the process of allocating, and what one should do in general when fewer pages are returned that requested. He wants to implement a userspace scatter-gather buffer and DMA directly into it without having an in-kernel copy operation (or splice perhaps). Hugh Dickens responded that it was appropriate to DMA into userspace directly, and that the general idea was right (including example code) although perhaps Leon is having a low-memory situation in userspace, lack of appropriate permissions, or has not setup the mmap size correctly.

VME. Greg Kroah-Hartman posted a 5 part patch series on behalf of Martyn Welch, who had implemented VME Bus support for the staging tree. Apparently, Martyn has been working with the three different existing implementations of VME support on Linux systems to merge them into a single official one. He sought out and received all the appropriate legal agreements in the process – good job there to Martyn and thanks to Greg for assisting in that effort.

In today’s miscellaneous items: a patch to pin kern mounts as writable (Dave Hansen), an XFS status update for July (Christoph Hellwig) containing little in the way of changes aside from some bug fixes, some wireless updates (John Linville), a patch dropping superfluous casts in nr_free_pages() callers from Geert Uytterhoeven (who I’d obviously forgotten was at Sony these days), a dialogue between Peter Zijlstra and Sherif Fadel concerning the latter’s desire to somehow treat a processor as a “scheduling co-processor” and have the scheduler treat it specially (for which Peter suggest the fix was to “write code”), some questions about whether Linux is booting on certain AMD Geode processors (specifically the SCx200 and LX800) – according to Martin-Eric Racine it has not been booting since 2.6.23 and 2.6.31-rc4 respectively on those Geode CPUs, a request from Ranjith Kannikara for help in decoding ext3 filesystems for some kind of (academic?) foresenic recovery project in progress, version 3 of a patch implementing avoidence of access to holes in vmalloc on reading from /proc/kcore (which had been causing crashes) from Kamezawa Hiroyuki, a patch to make block2mtd work with block devices larger than 4GB in size (Tobias Diedrich), a discussion surrounding the addition of a new scanning feature in MMC to detect which cards a controller supports in place of the existing scanning code (in which outgoing maintainer Pierre Ossman uses the line ‘Linux patches generally need to provide the answer to “Why?”, not just be able to avoid “Why not?”), generic support for ACPI ALS and other ALS devices (Zhang Rui), a trivial fix to kvm_init removing the debugfs entries if the architectural initialization fails, and a patch to scripts/get_maintainer.pl adding optional “git blame” checking of patches (Joe Perches).

Finally today. John Hawley repeated once again the fact that he (and other kernel.org folks also) are well aware that the code generating the front page links is out of date – and so is not creating links to mmotm/linux-next – and that it is on his radar and will be fixed in due course, just as soon as the fallout from other stuff (the bind exploits, conferences, and so forth) has settled and he has chance to move onto this activity.

In today’s announcements: AlacrityVM hypervisor project. In a world where there are many hypervisors, one man announced the creation of yet another. The AlacrityVM is based on KVM and is targeted specifically at performance sensitive workloads such as HPC and Real Time. There is more information about the project on the developer.novell.com website. There are already two mailing lists to discuss the project – I’ll be taking a look, as I’m sure will many other Real Time folks interested in shocking virtualization hybrid setups. Separately, Greg posted some guest drivers for the new VM.

The latest kernel release is 2.6.31-rc5, which was released by Linus on Friday.

Stephen Rothwell posted a linux-next tree for August 3rd. Since Friday, the new tty maintainer trees (tty.current, and tty) for Greg Kroah-Hartman has been added, and a net gain in build failures caused Stephen to do his usual herculean effort to fix up various trees and get the compose out of the door. There are now 138 sub-trees in the linux-next tree, with the addition of the tty trees.

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_20090802.mp3

Apologies for lagging behind. Last week was pretty busy and the box hosting the podcasts got attacked by script kiddies over the weekend. Here we go with a mega update round of podcasts for your edutainment.

For the weekend of August 2nd 2009, I’m Jon Masters with a summary of today’s LKML traffic.

In today’s issue: Big Kernel Lock, Futexes are tricky, Kbuild, Ksplice, MMC, RAR, TTY, and a tux3 filesystem update.

Big Kernel Lock. Frederic Weisbecker posted some ftrace tracing patches enabling Big Kernel Lock tracing and filter regex support for doing so. Using these patches, one can monitor BKL events (presumably with an eye toward removing them over time as part of the BKL reduction efforts underway). Separately, Federic also emailed to “announce” version 2 of the reiserfs/kill-bkl tree, which one assumes benefits from his ftrace patches in isolating and removing dependencies upon the Big Kernel Lock. His posting includes some benchmarks, and a lot more detail about his work.

Futexes are tricky. Eric Dumazet posted a nice summary of an ongoing infinite loop futex bug that several folks have been seeing on their kernels recently. As Eric says, clone() provides special support for the TID of created threads, allowing one to request that an integer in user memory be updated on creation (with it’s TID), and cleared on thread death. But because this integer location is in userspace memory, we need to be careful that the kernel doesn’t keep this pointer after an execve() – since the userspace is entirely replaced with another one. The fix is straightforward (setting clear_child_tid to NULL on execve to ensure the kernel will not try to write into it afterward).

Kbuild. Robert P J Day asked again whether there was any interest in a Kbuild “maturity level” that would enable one to attribute various levels of code maturity to kernel configuration options. For example “maturity DEPRECATED”, “maturity OBSOLETE”, or even “maturity BLEEDING_EDGE”. In many ways this feels like the existing EXPERIMENTAL dependency, but it is not a dependency. Instead, this is an entirely new kind of Kbuild attribute that is not as much “just plain hacky” as the existing support for enabling EXPERIMENTAL features. Speak now, or forever hold your peace. Robert would like your opinion.

Ksplice. Tim Abbott posted a preparatory patch series that cleans up the kerne’s explicit references to sections such as .data.page_aligned, .bss.page_aligned, and .data.init_task, replacing them with macros so that they can later be renamed if compiling with GCC -ffunction-sections -fdata-sections. This is a necessary pre-requesite for ksplice getting into the upstream kernel, although, of course it also helps those who want to compile the kernel using split out sections for reasons of memory footprint optimization and removal of unwanted code, for example on embedded systems.

MMC. Pierre Ossman (outgoing MMC maintainer) posted to let everyone know about the current patches that have been lingering in his inbox. These include patches for Intel Moorsetown, an “agressive clocking framework”, “prevent dangling blockdevice from accessing stale queues”, and a number of other patches. Many of them have hints about merge suitability and the idea was clearly to provide Andrew Morton (who has previously said that he now becomes the “de facto” MMC maintainer) with some hints to help him to get going. One hopes that someone else will step up and be in a position to take over rather than having Andrew keep stewardship of yet another kernel subsystem. Separately, Pierre posted his last “git pull” request for MMC.

RAR! Ossama Othman posted a series of patches implementing support for Intel Moorsetown supported Restricted Access Regions (RAR). These are regions of physical memory that cannot be accessed by the CPU (and thus Linux) once they have been locked down using RAR. Ossama notes that didn’t want to try fine grained page level allocations to lock down these regions, but instead wanted a blunt approach using a simple allocator. He has recently also discovered the lib/genalloc.c allocator though and suggests a future version may convert to using that allocator instead of providing his own. Comments are appreciated.

TTY. As hinted previously, it looks like Greg Kroah-Hartman really was stricken with some kind of horrible bug and decided to take on TTY maintainership. He posted a patch in which he says “Clearly, I am a glutton for punishment. I’ll see if I can see Alan’s changes through to the end, otherwise I’ll be fending off a lof of bug reports for usb-serial devices.” This suggests he has reluctantly concluded he might be the best person for the job right now. The MAINTAINERS patch includes a quilt tree, which he has asked Stephen Rothwell to begin to immediately pull into linux-next. Stephen followed up to say that he would be doing just that.

Tux3. The tux3 filesystem aims to offer various write-anywhere, atomic commit, fully versioned features of the kind that one can find in other modern file system projects currently under development. It is based on tux2, which was never released (apparently due to “evil patents sighted”) and is developed by (the highly vocal) Daniel Phillips – these days largely in his spare time. There have recently been a number of postings on the tux3 mailing list, cross posted to LKML, concerning the future of the project and how more volunteers could be encouraged to help, given that Daniel is short on time himself. He has posted some janitorial projects that those interested in getting involved can look into. More generally, Ted T’so suggested that Daniel consider what exactly tux3 offers as it’s main selling points over and above other filesystems – perhaps echoing the thoughts of others who might be wondering exactly why another filesystem is needed to compete with btrfs.

In today’s miscellaneous items: Gui Jianfeng posted some followup benchmarks of Vivek Goyal’s IO scheduler based IO controller (version 7 thereof) showing even better performance figures (for fairness set to zero as before), some ALSA trivial fixes (Takashi Iwai), some Fujitsu laptop specific fixes (Jonathan Woithe), some kmemleak detected memory leak fixes in case radeon_driver_load_kms fails on startup (Xiatian Feng), some (network related) kmemleak reports from Zdenek Kabelac, an explanation of the relative support status of RTL8192SE parts vs. over Realtek network chipsets (Barlomiej Zolnierkiewicz), Roger Quadros followed up as a result of his own previous question concerning use of generic CPU GPIO pins to drive voltage regulator circuitry with a patch he had produced, a fix from Robert Richter to avoid losing samples within the ring_buffer code if a padding event is returned from ring_buffer_consume calling rb_buffer_peek (leading to rb_advance_reader() being called twice) – he also posted a fix for rb_buffer_peek itself, some block bits from Jens Axboe (described as “some minor bits”), some additional x86 fixes from Peter Anvin, version 3 of the previously featured ummunotify, a comment from Frederic Weisbecker that the “Big Kernel Lock” page on the upstream RT wiki was not writeable (which turned out to mean that anonymous writes are not allowed without creating a user account first, as he later noted in a followup message), some x86 IOAPIC simplification and bugfixes (Cyrill Gorcunov), a ctags usability fix (Stefani Seibold), a question about “problems with CONFIG_KVM_GUEST” from Ted T’so (including the exact commands that he is using to start up the qemu backed KVM guests for ext4 testing), a series of “semantic patch” changes fixing various minor readability problems (Julia Lawall), a patch moving resource counters to percpu counters (Balbir Singh), a watchdog fix (Wim Van Sebroeck – only a single fix for a specific device that needs additional interrupt handling logic), some md fixes (Neil Brown), some earlyprintk improvements for those seeking to be debugging over EHCI USB devices on x86 platforms (Jason Wessel), some XFS fixes (Felix Blyakher), a fix for the /proc/kcore reading panic (Kamezawa Hiroyuki), a new “virtio” IDs file to make assigning new IDs much easier and less error prone than it had been having them all over the kernel sources (Fernando Luis Vazquez Cao), and someone else asked about mm/linux-next releases being on the front page of kernel.org once again (Dave Young).

A security item: Ulrich Drepper pointed out an information leak in signalstack caused because the stack_t data structure was defined “before people cared much about 64-bit architectures”. It has a hole in the middle that can leak information to userspace.

In today’s announcements: Linux 2.6.31-rc5. Linus Torvalds announced Release Candidate 5 of the upstream Linux kernel, on Friday evening at 17:49 (PDT). Linus says he wanted to push this now because there are a number of fixes for regressions whereas he’s not so sure about some of the stuff still queued so he wants to get this out there first. Gene Haskett has already posted a fresh crash report before his “amanda” backup process ran, showing a “bad page state” in a tar task. Gene is seeking suggestions to track this down.

Upstart version 0.6.3. Scott James Remnant announced version 0.6.3 of upstart, which includes a bugfix for a job’s main process being terminated while it is already in a stopping state, and a number of other bug fixes. Scott strongly suggests that those distributions using 0.3 migrate to 0.6 in order to help detect and correct bugs in the code, and to benefit from various features present in newer releases of the legacy init replacement.

The latest kernel release is 2.6.31-rc5, which was released by Linus on Friday evening.

Rafael J. Wysocki posted a list of regressions introduced between 2.6.29 and 2.6.30, and also a list of regressions introduced from 2.6.30. The list shows a recent drop in unresolved regressions (co-incidental with Linus’ latest release, which was heavy on regression fixes), but there are still a number of nasty problems there. Separately, Rafael posted individual bugzilla updates.

Stephen Rothwell posted a linux-next tree for July 31st. Since Thursday, the requested OProfile tree was added, Catalin Marinas’ kmemleak tree was undropped as the build failure was resolved, and a number of other trees overall lost their build failures. With the addition of the oprofile tree, there are now 136 sub-trees in the linux-next compose. I shall discontinue notifying that the powerpc tree doesn’t build in an allyesconfig build configuration because it hasn’t done so in many months at this point.

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_20090730.mp3

Apologies for lagging behind. Last week was pretty busy and the box hosting the podcasts got attacked by script kiddies over the weekend. Here we go with a mega update round of podcasts for your edutainment.

For Thursday, July 30th, 2009, I’m Jon Masters with a summary of today’s LKML traffic.

In today’s issue: CFQ, dm-ioband, MMC, OOM, and the Montreal Power management mini-summit.

CFQ. Shan Wei posted a first attempt at documenting the CFQ (Completely Fair Queing) IO elevator’s tunables. His document goes into quite some detail concerning how one can define timings, data sizes, idle timeouts, and quantum sizes and is worth reading.

dm-ioband. Ryo Tsuruta announced version 1.12.2 of the dm-ioband patches, which is a minor update and rebase to the current dm-devel tree. Ryo asked Alasdair Kergon for his thoughts in regard to merging the dm-ioband patches into upstream. Let’s not forget that there are about three different competing IO bandwidth limiting patchsets at the moment, so if this ends up upstream it will have a significant headstart on the others (for example Vivek Goyal’s IO controller based bandwidth patches) that are still in RFC.

MMC. Segher Bossenkool followed up to the previous discussion of MMC specs with a note that the MMC Assocation has merged with JEDEC, and so the specs are now available freely online at the jedec website. This should aid whoever decides to pick up maintainership of the MMC stack.

OOM. David Rientjes followed up to previous discussion of his patches introducing a new per-task oom_adj_child. He notes that the OOM killer now only relies upon the highest oom_adj score for multiple threads sharing an mm since otherwise there would be an inconsistency in reporting oom_score *and* a livelock potential in the case that one thread set OOM_DISABLE. David suggests that while this is a behavioral change for those who expect setting a thread oom_adj to not affect other threads, it is better than a livelock, and there exists now an inheritable parameter oom_adj_child that one can use instead to inform the OOM killer about the default oom_adj value for newly cloned tasks.

The Montreal Linux Power Management Mini-Summit. Len Brown posted some minutes from the power management “mini-summit” that took place concurrent with the Montreal Linux Symposium a couple of weeks ago. This time, the summit had been open to non-invitees to drop in if they felt so inclined. Some did so. The topics of discussion apparently included ACPI platform BIOS compatibility fixes, hibernation, suspend/resume framework rework by Rafael J. Wysocki, power aware scheduling, tools, and a lot more. The full email was quite long and thoroughly comprehensive, so look for it if you have further interest.

In today’s miscellaneous items: some fixes from Huang Ying that enable the MCE testsuite to work properly, a suggestion from Pavel Machek that the uid mount options for ext2 and ext3 default to an uid other than root (for example, -1), which is less “dangerous”, some chiding of Thomas Hellstrom (also from Pavel Machek) that he was “slowing the kernel down” without adequately explaining himself in making x86 use clflush() instead of wbinvd() in changing memory mappings, a missing mutex lock discovered using a French “semantic patch” tool (Stoyan Gaydarov) – the tool, Coccinelle looks worthy of investigation, a request to pull powerpc updates (Benjamin Herrenschmidt), an minor attack on grubby (the tool used on Fedora systems to automatically add entries to GRUB), some GFS2 fixes (Steven Whitehouse – including some pre-pull requests), a confirmation that Eric Dumazet’s fix to the infinite loop in get_futex_key solves the problem in 24 hours of testing (Jens Roseboom – who adds a “tested-by” signoff), a suggestion from Chris Mason that it’s ok to now send READA hints (instead of the READs currently being sent down) in bios to the elevator since it won’t become a transient failure any more like it used to on occasion, some scheduler fixes (Gregory Haskins), a quota fix to silence a lockdep warning (Jan Kara), some UDF fixes (also Jan Kara), some questions about interrupt state preservation (Michael S. Zick), some btrfs updates (Chris Mason), a simple fix to add new devices to a bus’ list before probing (Alan Stern), some tracing and timers fixes (Thomas Gleixner), a question about Thinkpad X20 docking support – or lack thereof – (Meelis Roos), a CPU hotplug fix so memory allocated at insertion is not lost on removal for CPUMASK_OFFSTACK=y (Li Xefan), some lguest and virtio fixes (Rusty Russell), version 13 of the per-bdi writeback flusher threads patch series from Jens Axboe, and Roger Quadros inquired as to the best way to control a voltage regulator using GPIO pins of his (one presumes embedded) CPU with the regulator framework.

Finally today, Zhao Lei posted version 4 of his calendar time to broken down time for universal use patches, including use of a long type for tm.tm_year. Evidentally the concerns about supporting beyond 2 billion years were serious enough to warrent the Linux kernel’s calendar support outliving our own Sun.

In today’s announcements: Greg Kroah-Hartman announced linux 2.6.27.29 and .30.4, encouraging all users of these “stable” series kernels to upgrade.

The latest kernel release was 2.6.31-rc4, which was superceeded by 2.6.31-rc5 by the time Friday came around.

Andrew Morton released an mm-of-the-moment for 2009-07-30-05-01, against -rc4.

Stephen Rothwell posted a linux-next tree for July 30th. Since Wednesday, the kmemleak tree is really included this time (it was acidentally ommitted even though yesterday’s announcement said it had been incorporated), but it was dropped shortly thereafter on a temporary basis due to a build problem. The tree fails to build in an allyesconfig build configuration on powerpc and a number of other gains and losses were recorded in other subtrees. The total tree count within the linux-next compose remains at 135 trees.

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_20090729.mp3

Apologies for lagging behind. Last week was pretty busy and the box hosting the podcasts got attacked by script kiddies over the weekend. Here we go with a mega update round of podcasts for your edutainment.

For Wednesday, July 29th, 2009, I’m Jon Masters with a summary of today’s LKML traffic.

In today’s issue: Clocksources, kmap vs kmap_atomic, nested virtualization, page cache readahead, and the tty layer deathmarch.

Clocksource. As mentioned previously, Martin Schwidefsky had found the clocksource switching code to be broken on his systems and was working on providing a fix. This has now turned into a quote “full fledged code rework” that is currently providing him with clocksource switching on s390 and Athlon systems – the latter having a broken TSC clocksource. Martin’s code rework is using stop_machine to effect the actual switchi (and a watchdog to trigger a switch if needed), which is expensive but should not called all that often. Martin thanks the usual suspects (John Stultz in particular) for their aid.

Kmap vs. kmap_atomic. Laurent Pinchart previously inquired about the relative merits of using fixed and persistent mappings vs. atomic in-interrupt mappings for copying in-flight video data pages received over USB. Jonathan Corbet (LWN) followed up suggesting that Laurent consider not performing the actual copy from within interrupt context but instead avail himself of more straightforward solutions outside of the interrupt handler. Of course, with threaded interrupt handlers, this situation could change somewhat. Laurent followed up with a round of discussions concerning the best ways to allocate DMA-able memory and ensure it is present – various others have helped to straighten out his understanding and use of technical terms accordingly.

Nested virtualization. Joerg Roedel posted a 12 part patch series implementing nested SVM cleanups and allowing one to successfully perform “KVM in KVM”, even when using nested SMP. The patches include support for intelligently handling the nesting of e.g. vmexit, vmrun, and nested intercepts so that the performance impact of the nested virtualization is not as significant as otherwise might have been the case. There was considerable discussion surrounding these patches, including various implementation questions.

Page cache readahead. Lars Ellenberg, after conducting some profiling runs, posted asking why __do_page_cache_readahead submits READ bios and not READA bios to the block layer. Lars noted that he “was surprised that READA is basically only used for filesystem internal meta data (and not ever for all file systems), but _never_ for file data. Various others followed up suggesting that it used to be the case that more READA requests had been submitted, but that this had other problems and so the kernel had switched at some point. Jens Axboe suggested that the behavior change wasn’t intentional but that he had done various testing in the past – he posted a link to some patches.

TTY. Discussions (or rather somewhat “heated” dialog) continued between Alan and Linus concerning the TTY layer and various outstanding issues with it (add to that a report today from Mikael Petterson that the GCC testsuite breaks on -rc4 based systems – in GNU “expect”). Alan continued to raise a number of issues with Linus’ description of the problems and his proposals to work around some of them. As part of the TTY layer discussions and testing of fixes, Andrew Morton provided Gene Haskett with an updated link to the latest “git-quick” tutorial, which he noted “some dope” had removed from its previous location on kernel.org. Gene will use this to pull a particular version of the kernel tree containing a fix that Linus would like him to test on his system(s). Separately, Catalin Marinas mentions a new VT memory leak.

In today’s miscellaneous items: A suggestion of a possible SLAB entry leak (task_delay_info) from Paul Rolland in -rc4 (for which he provided OOM output, and slabtop information), a confirmation that the previous infinite loop in get_futex_key is still present (Jens Rosenboom – who sent a reproducer), a note (Sam Ravnborg) that he thinks online mailing list archives for kernel.org are generally setup manually and not using some automated process (I can confirm that this appears to be true for archives such as gmane.org), a note (Dave Airlie) that a recent bug really only affects combination Intel IGP/AGP systems (AGP and IOMMU) to which David Woodhouse responded that he wondered how this would affect those with plugin cards on IOMMU systems, some staging radeon kms updates (also Dave Airlie – who is pulling these into F12), a question concerning network hangs on 2.6.12 (allegedy also affecting more less-dead recent kernels), a promised followup posting from Gui Jianfeng concerning Vivek Goyal’s latest IO scheduler patches (this time showing a performance loss of up to 4.9%, which is lower than previous test runs – there are of course also performance gains in some tests also), a patch from Mel Gorman that improves hugepage allocation success rates, a patch from Stanislaw Gruszka (and another similar one targeting POSIX CPUCLOCKs) that aims to improve itimers periodic ticks precision, a conversion of the hv driver in staging to use struct hv_driver (Nicolas Palix), some post scheduling fixes from Gregory Haskins (and Steven Rostedt and Peter Zjilstra), a repost of additional locking support in kmemleak from Catalin Marinas, the addition of LZO compression support for initramfs (Albin Tonnerre), some tracing cleanups (Frederic Weisbecker), a new bug (13850) oops reading /proc/kcore (Mike Smith), ongoing dicussion of the fanotify patches (Eric Paris, and also others), a pull request for wireless updates (John Linville), page allocator trace events from Mel Gorman, some power management fixes (Rafael J. Wysocki), and some clarity on the get_futex_key infinite loop problem (a suggestion from Eric Dumazet that execve() probably forgets to clear clear_child_tid).

In today’s announcements: Git version 1.6.34 and Git 1.6.4. Junio C Hamano once again delighted us with the announcement of several git releases. Some fairly annoying bugs are fixed in these releases, which may be of interest.

Also today, 2.6.31-rc4-rt1. Thomas Gleixner announced the latest release of the “RT” kernel patches ported to 2.6.31-rc4. As covered previously, there are a large number of changes to the underlying architecture in the latest update.

The latest kernel release was 2.6.31-rc4, although a newer rc5 was subsequently released on Friday evening.

Stephen Rothwell posted a linux-next tree for July 29th. Since Tuesday a new kmemleak tree has been provided by Catalin Marinas, Alan Cox’s former ttydev tree has been removed (at Alan’s invocation), the tree still fails to build in an allyesconfig build configuration on powerpc, and the drbd and staging trees gained conflicts against other trees. The subtree count remains steady at 135 trees since the removal of one tree was offset by the addition of another.

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