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Cisco Bug: CSCvu30088 - WNCD kernel process memory leak

Last Modified

Aug 29, 2020

Products (64)

  • Cisco IOS
  • Cisco Catalyst 9300-48U-A Switch
  • Cisco Catalyst 9300-48P-A Switch
  • Cisco Catalyst 9200L-48PXG-2Y Switch
  • Cisco Catalyst 9410R Switch
  • Cisco Catalyst 9300-48UN-A Switch
  • Cisco Catalyst C9500-16X-E Switch
  • Cisco Catalyst 9300-48T-A Switch
  • Cisco Catalyst 9300-48UXM-A Switch
  • Cisco Catalyst C9500-32QC Switch
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Known Affected Releases

Gibraltar-16.11.1

Description (partial)

Symptom:
When monitoring memory utilization for all kernel processes over several days with the following command: 

* show platform software process memory switch active r0 all sorted

You will see that memory utilization for WNCD process keeps increasing and never goes down: 


Pid       RSS       PSS      Heap    Shared   Private              Name  
--------------------------------------------------------------------------
 31414    829240    709043    156168    164540    664700            wncd_0  << 829MBs
 31414    831592    711393    156168    164544    667048            wncd_0  
.
.
.  
 31414    908160    787787    156168    164832    743328            wncd_0  
 31414    910840    790463    156168    164840    746000            wncd_0 << + 81.6 MBs


This is the result of a leak in WNCD_DB, and this can be checked with the following command: 

* show platform software memory database wncd switch active r0 callsite

Under "Database name: WNCD_DB" you will see the following callsite has a significantly larger "bytes" value (used memory):

Database name: WNCD_DB

  Callsite      Calls         Bytes
  --------------------------------------------------

  2013877258    8600844       324845624      <<<<    324MBs <<< Here we see that we're hitting this bug. 

Bytes for 2013877258:
217054384 << Day 1.
219275400
.
.
.
318293568
320472840
322659376
324845624   <<< 107MBs on Day 4.

Conditions:
The bug arises during CDP payloads of each AP reaches eWLC.
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