kswapd in D state does slow down the whole system

This document (7007279) is provided subject to the disclaimer at the end of this document.

Environment


SUSE Linux Enterprise Server 10 Service Pack 3

Situation

kswapd is hogging the CPU by parking itself on state 2 (TASK_UNINTERRUPTIBLE).
This does also happen when swap is turned off. Furthermore, there is a high IO activity, whereas just a small amount of RAM is being used.

A generated crashdump does show the following backtrace:

crash> bt ffff810323e607d0
PID: 198    TASK: ffff810323e607d0  CPU: 1   COMMAND: "kswapd0"
 #0 [ffff810323e81c88] schedule at ffffffff802f010b
 #1 [ffff810323e81d60] schedule_timeout at ffffffff802f0cac
 #2 [ffff810323e81db0] io_schedule_timeout at ffffffff802f04d4
 #3 [ffff810323e81de0] blk_congestion_wait at ffffffff801f1e5c
 #4 [ffff810323e81e30] balance_pgdat at ffffffff8016c2b8
 #5 [ffff810323e81ee0] kswapd at ffffffff8016cbe6
 #6 [ffff810323e81f50] kernel_thread at ffffffff8010bec6

Resolution

It appears that the issue is due to the lack of large memory chunk. As consequence of this,  a high order allocation (like 10) does fail.

This bug has been fixed and released with kernel version 2.6.16.60-0.74.7.
To fix this issue, update the kernel to the above release or a posterior one.

Additional Information


Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:7007279
  • Creation Date: 01-Dec-2010
  • Modified Date:03-Mar-2020
    • SUSE Linux Enterprise Server

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