kernel news – 07.07.2012

Posted: July 7, 2012 in kernel

Hello world! Here’s some kernel news to compensate the fact that I missed the release
of -rc5 :P

-Arnaldo Carvalho de Melo has perf/core fixes/improvements, Neil Brown
has md fixes, Dave Airlie has a small drm pull request and Jens Axboe has
block fixes for -rc :

– Two patches for mtip32xx. Killing a non-compliant sysfs interface and
moving it to debugfs, where it belongs.

– A few patches from Asias. Two legit bug fixes, and one killing an
interface that is no longer in use.

– A patch from Jan, making the annoying partition ioctl warning a bit
less annoying, by restricting it to !CAP_SYS_RAWIO only.

– Three bug fixes for drbd from Lars Ellenberg.

– A fix for an old regression for umem, it hasn’t really worked since
the plugging scheme was changed in 3.0.

– A few fixes from Tejun.

– A splice fix from Eric Dumazet, fixing an issue with pipe resizing.

-Brian Wu has led fixes, Ben Hutchings announces 3.2.22, Marcelo Tosatti
updates kvm for -rc5, Chris Mason has btrfs updates, Joel Becker has ocfs2
fixes for -rc5, and there are IOMMU fixes from Joerg Roedel :

The patches fix several issues in the AMD IOMMU driver, the NVidia SMMU
driver, and the DMA debug code. The most important fix for the AMD IOMMU
solves a problem with SR-IOV devices where virtual functions did not
work with IOMMU enabled. The NVidia SMMU patch fixes a possible sleep
while spin-lock situation (queued the small fix for v3.5, a better but
more intrusive fix is coming for v3.6). The DMA debug patches fix a
possible data corruption issue due to bool vs. u32 usage.

-Paul E. McKenney has RCU commits for 3.6:

1. Preventing latency spikes of more than 200 microseconds for
kernels built with NR_CPUS=4096, which is reportedly becoming
the default for some distros. This is a first step, as it does
not help with systems that actually -have- 4096 CPUs (work on
this case is in progress, but is not yet ready for mainline).
This category also includes improving concurrency of rcu_barrier(),
placed here due to conflicts. Posted to LKML at: Note that patches 18-22
of that series have been defered to 3.7, as they have not yet
proven themselves to be mainline-ready (and yes, these are the
ones intended to get rid of RCU’s latency spikes for systems
that actually have 4096 CPUs).
2. Updates to documentation and rcutorture fixes, the latter category
including improvements to rcu_barrier() testing. Posted to LKML at:
3. Miscellaneous fixes posted to LKML at:, with the exception of the
last commit, which was posted here:
4. RCU_FAST_NO_HZ fixes and improvements. Posted to LKML at:
The first four patches of the first series went into 3.5 to fix
a regression.
5. Code-style fixes. These were posted to LKML at and

All of this code has been exposed to -next testing.

These changes are available in the git repository at:

git:// rcu/next

-That’s it, enjoy the weekend.


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