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DescriptionDave Wysochanski
2022-12-12 14:06:10 UTC
Description of problem:
This problem seems to have popped up in more recent kernels, and I don't think it's due to damaged vmcore.
The mount command output looks like this on some vmcores now:
crash> mount
MOUNT SUPERBLK TYPE DEVNAME DIRNAME
ffff9d0c067e0f00 ffff9d0c00014800 rootfs none /
...
ffff9d10258e5a20 0 mount: invalid kernel virtual address: 0 type: "super_block buffer"
Version-Release number of selected component (if applicable):
crash-7.3.1-5.el8.x86_64
upstream crash (latest 8.x) also seems affected
How reproducible:
Easy
Steps to Reproduce:
1. Run crash against an affected vmcore
2. Use 'mount' command
Actual results:
the last line of 'mount' command output looks like this:
ffff9d10258e5a20 0 mount: invalid kernel virtual address: 0 type: "super_block buffer"
Expected results:
the last line should contain valid data
Additional info:
There's multiple instances of this problem on our production system and I'll put into the private comments or you can just search on our system for it in the 'results' directory of all vmcores on production vmcore system. This first showed up through pykdump command which uses 'mount' command and then parses output for some commands. However just running the command directly from crash gives the same output so this is definitely an issue with crash, not pykdump.
I only briefly started investigating this. I think we'll need an upstream patch and then a clone for RHEL9 of this bug, assuming I didn't miss anything like some damage to vmcore(s) that are affected. This doesn't happen on a lot of vmcores but if it's starting to affect later vmcores then we may see more of it. Given the likely higher use of 'mount' command I'm marking as 'medium' severity for now.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory (crash bug fix and enhancement update), and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHBA-2023:6947
Description of problem: This problem seems to have popped up in more recent kernels, and I don't think it's due to damaged vmcore. The mount command output looks like this on some vmcores now: crash> mount MOUNT SUPERBLK TYPE DEVNAME DIRNAME ffff9d0c067e0f00 ffff9d0c00014800 rootfs none / ... ffff9d10258e5a20 0 mount: invalid kernel virtual address: 0 type: "super_block buffer" Version-Release number of selected component (if applicable): crash-7.3.1-5.el8.x86_64 upstream crash (latest 8.x) also seems affected How reproducible: Easy Steps to Reproduce: 1. Run crash against an affected vmcore 2. Use 'mount' command Actual results: the last line of 'mount' command output looks like this: ffff9d10258e5a20 0 mount: invalid kernel virtual address: 0 type: "super_block buffer" Expected results: the last line should contain valid data Additional info: There's multiple instances of this problem on our production system and I'll put into the private comments or you can just search on our system for it in the 'results' directory of all vmcores on production vmcore system. This first showed up through pykdump command which uses 'mount' command and then parses output for some commands. However just running the command directly from crash gives the same output so this is definitely an issue with crash, not pykdump. I only briefly started investigating this. I think we'll need an upstream patch and then a clone for RHEL9 of this bug, assuming I didn't miss anything like some damage to vmcore(s) that are affected. This doesn't happen on a lot of vmcores but if it's starting to affect later vmcores then we may see more of it. Given the likely higher use of 'mount' command I'm marking as 'medium' severity for now.