[Crash-utility] crash-7.3.2 very long list iteration progressively increasing memory usage

[David Wysochanski]

Hi Dave,

We have a fairly large vmcore (around 250GB) that has a very long kmem
cache we are trying to determine whether a loop exists in it.  The list
has literally billions of entries.  Before you roll your eyes hear me
out.

Just running the following command
crash> list -H 0xffff8ac03c81fc28 > list-yeller.txt

Seems to increase the memory of crash usage over time very
significantly, to the point that we have the following with top output:
  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                                                                                                         
25522 dwysocha  20   0 11.2g  10g 5228 R 97.8 17.5   1106:34 crash    

                                                                       
                                              When I started the
command yesterday it was adding around 4 million entries to the file
per minute.  At the time I estimated the command would finish in around
10 hours and I could use it to determine if there was a loop in the
list or not.  But today has slowed down to less than 1/10th that, to
around 300k entries per minute.

Is this type of memory  usage with list enumeration expected or not?

I have not yet begun to delve into the code, but figured you might have
a gut feel whether this is expected and fixable or not.

Thanks.