5.37. crash

If the kernel was configured with the Completely Fair Scheduler (CFS) Group Scheduling feature enabled (CONFIG_FAIR_GROUP_SCHED=y), the "runq" command of the crash utility did not display all tasks in CPU run queues. This update modifies the crash utility so that all tasks in run queues are now displayed as expected. Also, the "-d" option has been added to the "runq" command, which provides debugging information same as the /proc/sched_debug file.

The "bt" command previously did not handle recursive non-maskable interrupts (NMIs) correctly on the Intel 64 and AMD64 architectures. As a consequence, the "bt" command could, under certain circumstances, display a task backtrace in an infinite loop. With this update, the crash utility has been modified to recognize a recursion in the NMI handler and prevent the infinite displaying of a backtrace.

Under certain circumstances, the number of the "elf_prstatus" entries in the header of the compressed kdump core file could differ from the number of CPUs running when the system crashed. If such a core file was analyzed by the crash utility, crash terminated unexpectedly with a segmentation fault while displaying task backtraces. This update modifies the code so that the "bt" command now displays a backtrace as expected in this scenario.

Recent changes in the code caused the crash utility to incorrectly recognize compressed kdump dump files for the 64-bit PowerPC architecture as dump files for the 32-bit PowerPC architecture. This caused the crash utility to fail during initialization. This update fixes the problem and the crash utility now recognizes and analyzes the compressed kdump dump files for the 32-bit and 64-bit PowerPC architectures as expected.

The crash utility did not correctly handle situations when a user page was either swapped out or was not mapped on the IBM System z architecture. As a consequence, the "vm -p" command failed and either a read error occurred or an offset va1lue of a swap device was set incorrectly. With this update, crash displays the correct offset value of the swap device or correctly indicates that the user page is not mapped.

The crash utility did not correctly handle situations when the "bt -t" and "bt -T" commands were run on an active task on a live system on the IBM System z architecture. Consequently, the commands failed with the "bt: invalid/stale stack pointer for this task: 0" error message. This update modifies the source code so that the "bt -t" and "bt -T" commands execute as expected.

With this update, crash now supports the "sadump" dump file format created by the Fujitsu Stand Alone Dump facility.

The crash utility has been modified to fully support the "ELF kdump" and "compressed kdump" dump file formats for IBM System z.

The makedumpfile facility can be used to filter out specific kernel data when creating a dump file, which can cause the crash utility to behave unpredictably. With this update, the crash utility now displays an early warning message if any part of the kernel has been erased or filtered out by makedumpfile.