crash bug fix update

Updated crash packages that fix various bugs and add enhancements are now
available.

The crash package is a core analysis suite. It is a self-contained tool
that can be used to investigate either live systems, kernel core dumps
created from the netdump, diskdump, and kdump packages from Red Hat Linux,
the mcore kernel patch offered by Mission Critical Linux, or the LKCD
kernel patch.

* if a kdump NMI was issued and the task kernel stack was changed, the
backtrace would in some cases fail and produce an error: "bt: cannot
transition from exception stack to current process stack". The crash
package was updated to report task inconsistencies and change the active
task as appropriate. Additionally, a new set -a option was added to
manually set tasks to be the active task on its CPU. (BZ#504952)

* if the kernel data structures in a non-matching vmlinux varied widely
enough from the kernel that generated the vmcore, erroneous data could be
read and consumed. Several new defensive mechanisms have been added and it
now fails in a more reasonable manner. (BZ#508156)

* running the bt -a command against a Xen hypervisor resulted in a
"cannot resolve stack trace" warning message if the CPU received its
shutdown NMI while running in an interrupt handler. The bt command was
changed and the error no longer occurs. (BZ#510505)

* added support for dumpfile format of virsh dump of KVM kernels.
(BZ#510519)

* if a dump was collected when there were one or more cpus offline in the
system, an initialization-time failure would occur and the crash would
abort. A patch was backported from upstream and the failure no longer
occurs. (BZ#520506)

* running the 64-bit bt command could potentially start the backtrace of
an active non-crashing task on its per-cpu IRQ stack, cause a faulty
transition back to the process stack, the dumping of a bogus exception
frame and the message "bt: WARNING: possibly bogus exception frame". The
bt command was changed and it now starts from the NMI exception stack, the
error no longer occurs. (BZ#523512)

* when the cpu_possible_map contains more CPUs than the cpu_online_map, the
set, bt, runq and ps commands would reflect the existing but unused swapper
tasks on the non-existent CPUs. The 64-bit PowerPC CPU count determination
was fixed and the commands now run as expected. (BZ#550419)

* when INIT-generated pseudo-tasks were running in user-space and the
kernel was unable to modify the kernel stack, the backtrace would not
identify the interrupted task and would display a "bt: unwind: failed to
locate return link" error message. The Itanium backtraces were fixed, and
the backtrace now offers information regarding the task that was
interrupted. The error message is also suppressed. (BZ #553353)

* using dump to analyze very large xendump core files with ELF sections
located beyond a file offset of 4GB resulted in errors. Changes were made
to the xc_core_verify() initialization code and dump now works as expected.
(BZ #561767)

* The crash utility was rebased. See the changelog linked to in the
references section below for full details. (BZ#528184)

All users of crash are advised to upgrade to these updated packages,
which resolve these issues.

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

This update is available via Red Hat Network. Details on how to use
the Red Hat Network to apply this update are available at
http://kbase.redhat.com/faq/docs/DOC-11259

504952 - bt: cannot transition from exception stack to current process stack
510519 - [RHEL5.4 KVM]: Unimplemented "virsh dump" capability - crash utility support
528184 - Rebase request for crash utility RHEL5.5 errata
550419 - bt:cannot determine NT_PRSTATUS ELF note for active task
553353 - [5.4] Crash fails to backtrace on IA64 machine
561767 - xm dump-core creates dump that crash cannot process

http://people.redhat.com/anderson/crash.changelog.html