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** Changed in: linux (Ubuntu)
       Status: New => Incomplete

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https://bugs.launchpad.net/bugs/1811226

Title:
  ipvsadm --ops causes CPU soft lockup on traffic

Status in linux package in Ubuntu:
  Incomplete

Bug description:
  Using IPVS with One-Packet Scheduling on UDP causes CPU soft lockup on
  traffic.

  Steps to reproduce:

  1. Install ipvsadm and netcat-openbsd
  2. Execute `ipvsadm -a -u 127.0.0.1:1234 -s rr --ops && ipvsadm -A -u 
127.0.0.1:1234 -r 127.0.0.1:1235 -m -w 1`
  3. Execute `nc -l -k -u 1235` to actually have a listening service
  4. In another terminal, generate traffic `while sleep 0.01; do date | nc -u 
-w 0 127.0.0.1 1234; done`

  In only takes several packets (around 100 in my tests) to cause the
  soft lockup to appear. Even with lower packet rates (sleep 1 for
  example), the bug occurs.

  This problem is already fixed in the current 4.20 vanilla kernel but
  is present in the 4.15 vanilla kernel (tested packages from the
  kernel-ppa). So basically, this would be a backport.

  Ubuntu release: Ubuntu 18.04.1 LTS
  Kernel version: Ubuntu 4.15.0-43.46-generic 4.15.18

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