#989716 kdump-tools: kdump produces useless "dumps" on i386

Package:
kdump-tools
Source:
kdump-tools
Description:
scripts and tools for automating kdump (Linux crash dumps)
Submitter:
Rich Ercolani
Date:
2021-06-11 14:51:04 UTC
Severity:
important
#989716#5
Date:
2021-06-11 07:55:14 UTC
From:
To:
Dear Maintainer,

Installed kdump-tools appear to work, echo 'c' | sudo tee /proc/sysrq-trigger boots the crashkernel and
takes a dump and reboots, but attempting to use "crash" on the dump in a way that works
in other configurations (e.g. crash /usr/lib/debug/boot/vmlinux-1234 /var/crash/1234/dump.1234) reports
(in this example, on buster, with -d1):

crash: page excluded: kernel virtual address: c19546a4  type: "possible"
WARNING: cannot read cpu_possible_map
crash: page excluded: kernel virtual address: c195469c  type: "present"
WARNING: cannot read cpu_present_map
crash: page excluded: kernel virtual address: c19546a0  type: "online"
WARNING: cannot read cpu_online_map
crash: page excluded: kernel virtual address: c1954698  type: "active"
WARNING: cannot read cpu_active_map
crash: page excluded: kernel virtual address: c18c769c  type: "pv_init_ops"
crash: page excluded: kernel virtual address: c1a92268  type: "shadow_timekeeper xtime_sec"
xtime timespec.tv_sec: 9aee2b: Tue Apr 28 08:25:15 1970
crash: page excluded: kernel virtual address: c18bb1c4  type: "init_uts_ns"
utsname:
     sysname:
    nodename:
     release:
     version:
     machine:
  domainname:
base kernel version: 0.0.0
crash: page excluded: kernel virtual address: c16a9160  type: "accessible check"
crash: /usr/lib/debug/vmlinux-4.19.0-16-686-pae and /var/crash/202106110101/dump.202106110101 do not match!

And:
# ls -al /var/crash/202106110101/dump.202106110101;file /var/crash/202106110101/dump.202106110101;
-rw------- 1 root root 21422351 Jun 11 01:01 /var/crash/202106110101/dump.202106110101
/var/crash/202106110101/dump.202106110101: Kdump compressed dump v6, system Linux, node debian32, release 4.19.0-16-686-pae, version #1 SMP Debian 4.19.181-1 (2021-03-19), machine i686, domain (none)

crashkernel=512M-:192M, on here, changes the behavior to what #989714 describes on x86_64 -
no printouts from a crashkernel or anything else, no dump ever saved, just an indefinite hang.
crashkernel=384M-:192M (or 256M) does not hang, but produces an equally useless "dump".

According to the console output when this happens, "makedumpfile Completed" both times, and
dmesg's output appears intact and complete.

(I neglected to mention this in #989714, but these are all on VirtualBox-backed VMs.)

Please let me know if there's anything further I can do to help debug this.

- Rich
#989716#10
Date:
2021-06-11 14:47:27 UTC
From:
To:
So it sounds like you were able to get a successful dump after
adjusting crashkernel, is that correct? And the issue is that crash
doesn't deal with it? Wouldn't that be a bug in the crash tool then?

  -dann
#989716#15
Date:
2021-06-11 14:47:27 UTC
From:
To:
So it sounds like you were able to get a successful dump after
adjusting crashkernel, is that correct? And the issue is that crash
doesn't deal with it? Wouldn't that be a bug in the crash tool then?

  -dann