Description of problem: Crash can't open vmcore captured by kdump so that we can't perform debugging operations after a successful kdump. Version-Release number of selected component (if applicable): crash-7.1.5-2.fc25.x86_64 kernel-core-4.8.0-0.rc7.git0.1.fc26.x86_64 (patched to make kdump work) How reproducible: Steps to Reproduce: 1. Run 'echo c > /proc/sysrq-trigger' to get a kdump vmcore 2. crash /path/to/vmlinux /path/to/vmcore 3. Actual results: crash: page excluded: kernel virtual address: ffffffff81fdc940 type: "possible" WARNING: cannot read cpu_possible_map crash: page excluded: kernel virtual address: ffffffff81fdc140 type: "present" WARNING: cannot read cpu_present_map crash: page excluded: kernel virtual address: ffffffff81fdc540 type: "online" WARNING: cannot read cpu_online_map crash: page excluded: kernel virtual address: ffffffff81fdbd40 type: "active" WARNING: cannot read cpu_active_map crash: page excluded: kernel virtual address: ffffffff81e24090 type: "pv_init_ops" crash: page excluded: kernel virtual address: ffffffff83195df0 type: "shadow_timekeeper xtime_sec" crash: page excluded: kernel virtual address: ffffffff81e0d304 type: "init_uts_ns" crash: /usr/lib/debug/lib/modules/4.8.0-0.rc7.git2.1.fc26.x86_64/vmlinux and /var/crash/127.0.0.1-2016-09-23-10:42:18/vmcore do not match! Expected results: crash loads vmcore without error and give out a debug shell. Additional info: Building crash from master branch on github can solve this problem. https://github.com/crash-utility/crash
I'm hoping to do a Rawhide rebase in the next couple of weeks. The issue you're seeing is a due to the new CONFIG_RANDOMIZE_MEMORY configuration, which I fixed in the upstream crash repo last Wednesday: https://github.com/crash-utility/crash/commit/da79c1bffc287309ecebc9fe40f0a3cdf5a5d26d commit da79c1bffc287309ecebc9fe40f0a3cdf5a5d26d Author: Dave Anderson <anderson> Date: Wed Sep 21 15:58:22 2016 -0400 Fix to recognize and support x86_64 Linux 4.8-rc1 and later kernels that are configured with CONFIG_RANDOMIZE_MEMORY, which randomizes the base addresses of the kernel's unity-map address (PAGE_OFFSET), and the vmalloc region. Without the patch, the crash utility fails with a segmentation violation during session initialization. (anderson) Also, Fedora's 4.8.0 kernel also introduced CONFIG_HARDENED_USERCOPY, which will prevent crash from working on a live system. However, that will require a kernel patch to the /dev/crash driver to fix it. I have forwarded a patch to Josh Boyer (the Fedora kernel maintainer) last Thursday (?), and it should appear in Fedora kernels in the near future.
- Fedora Rawhide build: crash-7.1.6-1.fc26 (10/14/16) http://koji.fedoraproject.org/koji/buildinfo?buildID=810068