Red Hat Bugzilla – Bug 857111
The DUMPFILE field of vmcore showing "vmcore [PARTIAL DUMP]"
Last modified: 2012-09-13 13:28:05 EDT
Description of problem:
The DUMPFILE field of vmcore showing "vmcore [PARTIAL DUMP]" on RHEL6_U3.
Output from vmcore file
DUMPFILE: vmcore [PARTIAL DUMP]
DATE: Thu Sep 6 00:41:02 2012
LOAD AVERAGE: 302.68, 302.26, 300.01
VERSION: #1 SMP Wed Jun 13 18:24:36 EDT 2012
MACHINE: x86_64 (2000 Mhz)
MEMORY: 8 GB
PANIC: "Kernel panic"
TASK: ffff88011e8ff500 [THREAD_INFO: ffff88004681c000]
STATE: TASK_RUNNING (PANIC)
Steps to Reproduce:
1.generate the vmcore by cmd "echo c > /proc/sysrq-trigger"
2.read this vmcore using crash
3.DUMPFILE field will show "DUMPFILE: vmcore [PARTIAL DUMP]"
Is the meaning of [PARTIAL DUMP] means we havent got the full dump? can I do my investigation on this dump?
Also suggest if I miss any setting to take k-dump.
> 1.generate the vmcore by cmd "echo c > /proc/sysrq-trigger"
> 2.read this vmcore using crash
> 3.DUMPFILE field will show "DUMPFILE: vmcore [PARTIAL DUMP]"
> Is the meaning of [PARTIAL DUMP] means we havent got the full dump?
> can I do my investigation on this dump?
> Also suggest if I miss any setting to take k-dump
The system that crashed has been configured such that the vmcore is
filtered by the makedumpfile facility to remove unnecessary pages.
Check the crashed system's /etc/kdump.conf file. It probably has a
line that configures "core_collector" to something like this:
core_collector makedumpfile -c --message-level 1 -d 31
The -c means "compressed" and the "-d <number>" is a bitmask
that allows you to filter out zero-filled pages, page-cache
pages, user-program pages, and free-pages. This is the
relevant section from "makedumpfile --help":
Specify the type of unnecessary page for analysis.
Pages of the specified type are not copied to DUMPFILE. The page type
marked in the following table is excluded. A user can specify multiple
page types by setting the sum of each page type for Dump_Level (DL).
The maximum of Dump_Level is 31.
Note that Dump_Level for Xen dump filtering is 0 or 1.
Dump | zero cache cache user free
Level | page page private data page
1 | X
2 | X
4 | X X
8 | X
16 | X
31 | X X X X X
If your configuration also uses "-c" to make the vmcore file a
compressed dumpfile, you can use the crash utility itself to
access the dump-level value, like this example where -d31 was
crash> help -n | grep dump_level
dump_level: 31 (0x1f) (DUMP_EXCLUDE_ZERO|DUMP_EXCLUDE_CACHE|DUMP_EXCLUDE_CACHE_PRI|DUMP_EXCLUDE_USER_DATA|DUMP_EXCLUDE_FREE)
If "-c" was not used, then you would have to consult the /etc/kdump.conf
file on the crashed machine to see how it was configured.
In any case, it's highly unlikely that the contents of any of the
filterable page-types above are necessary to investigate the cause
of a kernel crash.