How to read, understand, analyze, and debug a Linux kernel panic?

Question

Consider the following linux kernel dump stack trace, you can trigger a panic from the kernel source code by calling panic(\"debugging a linux kernel panic\");:

Answer 1

Here are two alternatives for addr2line. Assuming you have the proper target's toolchain, you can do one of the following:

Use objdump:

1. locate your vmlinux or the .ko file under the kernel root directory, then disassemble the object file :

   objdump -dS vmlinux > /tmp/kernel.s
   

2. Open the generated assembly file, /tmp/kernel.s. with a text editor such as vim. Go to unwind_backtrace+0x0/0xf8, i.e. search for the address of unwind_backtrace + the offset. Finally, you have located the problematic part in your source code.

Use gdb:

IMO, an even more elegant option is to use the one and only gdb. Assuming you have the suitable toolchain on your host machine:

1. Run gdb .
2. Execute in gdb's prompt: list *(unwind_backtrace+0x10).

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For additional information, you may checkout the following resources:

1. Kernel Debugging Tricks.
2. Debugging The Linux Kernel Using Gdb