Issued:

2012-09-11

Updated:

2012-09-11

RHBA-2012:1254 - kernel bug fix and enhancement update

Synopsis

kernel bug fix and enhancement update

Type/Severity

Bug Fix Advisory

Topic

Updated kernel packages that fix three bugs and add two enhancements are now available for Red Hat Enterprise Linux 6 Extended Update Support.

Description

The kernel packages contain the Linux kernel, the core of any Linux operating system.

This update fixes the following bugs:

• Previously, the TCP socket bound to NFS server contained a stale skb_hints socket buffer. Consequently, kernel could terminate unexpectedly. A patch has been provided to address this issue and skb_hints is now properly cleared from the socket, thus preventing this bug. (BZ#846831)

• On Intel systems with Pause Loop Exiting (PLE), or AMD systems with Pause Filtering (PF), it was possible for larger multi-CPU KVM guests to experience slowdowns and soft lock-ups. Due to a boundary condition in kvm_vcpu_on_spin, all the VCPUs could try to yield to VCPU0, causing contention on the run queue lock of the physical CPU where the guest's VCPU0 is running. This update eliminates the boundary condition in kvm_vcpu_on_spin. (BZ#847041)

• Due to a missing return statement, the nfs_attr_use_mounted_on_file() function returned a wrong value. As a consequence, redundant ESTALE errors could potentially be returned. This update adds the proper return statement to nfs_attr_use_mounted_on_file(), thus preventing this bug. (BZ#847944)

This update adds the following enhancements:

• This update adds support for the Proportional Rate Reduction (PRR) algorithms for the TCP protocol. This algorithm determines TCP's sending rate in fast recovery. PRR avoids excessive window reductions and improves accuracy of the amount of data sent during loss recovery. In addition, a number of other enhancements and bug fixes for TCP are part of this update. (BZ#847732)

• This update affects performance of the O_DSYNC flag on the GFS2 file system when only data (and not metadata such as file size) has been dirtied as a result of the write() system call. Prior to this update, write calls with O_DSYNC were behaving the same way as with O_SYNC at all times. With this update, O_DSYNC write calls only write back data if the inode's metadata is not dirty. This results in a considerable performance improvement for this specific case. Note that the issue does not affect data integrity. The same issue also applies to the pairing of the write() and fdatasync() system calls. (BZ#849550)

All users are advised to upgrade to these updated packages, which fix these bugs and add these enhancements. The system must be rebooted for this update to take effect.

Solution

Before applying this update, make sure all previously-released errata relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to use the Red Hat Network to apply this update are available at https://access.redhat.com/knowledge/articles/11258

Affected Products

Updated Packages

• kernel-debuginfo-2.6.32-220.26.1.el6.s390x.rpm
• kernel-devel-2.6.32-220.26.1.el6.i686.rpm
• kernel-debug-2.6.32-220.26.1.el6.i686.rpm
• kernel-debuginfo-common-s390x-2.6.32-220.26.1.el6.s390x.rpm
• kernel-2.6.32-220.26.1.el6.x86_64.rpm
• kernel-2.6.32-220.26.1.el6.src.rpm
• kernel-headers-2.6.32-220.26.1.el6.s390x.rpm
• kernel-firmware-2.6.32-220.26.1.el6.noarch.rpm
• kernel-debug-devel-2.6.32-220.26.1.el6.s390x.rpm
• perf-debuginfo-2.6.32-220.26.1.el6.i686.rpm
• python-perf-debuginfo-2.6.32-220.26.1.el6.x86_64.rpm
• kernel-debuginfo-common-i686-2.6.32-220.26.1.el6.i686.rpm
• perf-2.6.32-220.26.1.el6.i686.rpm
• kernel-headers-2.6.32-220.26.1.el6.ppc64.rpm
• kernel-debug-debuginfo-2.6.32-220.26.1.el6.i686.rpm
• python-perf-2.6.32-220.26.1.el6.ppc64.rpm
• kernel-debug-2.6.32-220.26.1.el6.ppc64.rpm
• kernel-devel-2.6.32-220.26.1.el6.s390x.rpm
• kernel-debug-devel-2.6.32-220.26.1.el6.x86_64.rpm
• kernel-bootwrapper-2.6.32-220.26.1.el6.ppc64.rpm
• kernel-debuginfo-2.6.32-220.26.1.el6.x86_64.rpm
• python-perf-debuginfo-2.6.32-220.26.1.el6.i686.rpm
• kernel-debuginfo-common-x86_64-2.6.32-220.26.1.el6.x86_64.rpm
• kernel-debuginfo-2.6.32-220.26.1.el6.i686.rpm
• kernel-kdump-debuginfo-2.6.32-220.26.1.el6.s390x.rpm
• perf-debuginfo-2.6.32-220.26.1.el6.x86_64.rpm
• perf-2.6.32-220.26.1.el6.s390x.rpm
• kernel-devel-2.6.32-220.26.1.el6.ppc64.rpm
• python-perf-2.6.32-220.26.1.el6.s390x.rpm
• python-perf-debuginfo-2.6.32-220.26.1.el6.s390x.rpm
• python-perf-2.6.32-220.26.1.el6.i686.rpm
• kernel-debug-devel-2.6.32-220.26.1.el6.i686.rpm
• kernel-headers-2.6.32-220.26.1.el6.x86_64.rpm
• kernel-debuginfo-common-ppc64-2.6.32-220.26.1.el6.ppc64.rpm
• kernel-debug-debuginfo-2.6.32-220.26.1.el6.x86_64.rpm
• kernel-debuginfo-2.6.32-220.26.1.el6.ppc64.rpm
• perf-2.6.32-220.26.1.el6.ppc64.rpm
• kernel-debug-2.6.32-220.26.1.el6.s390x.rpm
• kernel-2.6.32-220.26.1.el6.s390x.rpm
• python-perf-2.6.32-220.26.1.el6.x86_64.rpm
• kernel-debug-2.6.32-220.26.1.el6.x86_64.rpm
• kernel-debug-debuginfo-2.6.32-220.26.1.el6.s390x.rpm
• kernel-debug-devel-2.6.32-220.26.1.el6.ppc64.rpm
• kernel-doc-2.6.32-220.26.1.el6.noarch.rpm
• perf-debuginfo-2.6.32-220.26.1.el6.ppc64.rpm
• kernel-kdump-devel-2.6.32-220.26.1.el6.s390x.rpm
• perf-2.6.32-220.26.1.el6.x86_64.rpm
• kernel-devel-2.6.32-220.26.1.el6.x86_64.rpm
• kernel-headers-2.6.32-220.26.1.el6.i686.rpm
• python-perf-debuginfo-2.6.32-220.26.1.el6.ppc64.rpm
• perf-debuginfo-2.6.32-220.26.1.el6.s390x.rpm
• kernel-2.6.32-220.26.1.el6.ppc64.rpm
• kernel-kdump-2.6.32-220.26.1.el6.s390x.rpm
• kernel-debug-debuginfo-2.6.32-220.26.1.el6.ppc64.rpm
• kernel-2.6.32-220.26.1.el6.i686.rpm

Fixes

• This content is not included.BZ - 847944

CVEs

(none)

References

(none)

Additional information

• The Red Hat security contact is This content is not included.secalert@redhat.com. More contact details at https://access.redhat.com/security/team/contact/.
• Offline Security Data data is available for integration with other systems. See Offline Security Data API to get started.