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Cisco Bug: CSCvt27834 - Persisted MTS evmc queues "sup/342/pers" causes memory leak

Last Modified

Mar 20, 2020

Products (1)

  • Cisco Nexus 7000 Series Switches

Known Affected Releases

7.3(1)D1(1)

Description (partial)

Symptom:
Enormous memory leak were logged in logfile and it says [sap 342][pid 5734][comm:evmc] like below.
2020 Feb 18 12:01:50.487 xxxx-01-1 %$ VDC-1 %$ %KERN-2-SYSTEM_MSG: [31114072.190446] [sap 342][pid 5734][comm:evmc] WARNING: possible memory leak is detected on pers queue (len=36684,bytes=37561600) - kernel
So I checked `show system internal mts buffers summary` and `show system internal mts buffers details` and following Node/Sap/queue=sup/342/pers whose age was too long were listed.

`show system internal mts buffers summary`
node    sapno    recv_q    pers_q    npers_q    log_q
sup    48400    4    0    0    0
sup    284    0    3    0    0
sup    342    0    36673    0    0

`show system internal mts buffers details`
...
sup/342/pers	31345369347    	0x901       	342	0x901       	342	1680	0xf76b	540	0xf76b	0xfac8804
sup/342/pers	31345369346    	0x901       	342	0x901       	342	1680	0xf772	540	0xf772	0xfa20004
sup/342/pers	31345369345    	0x901       	342	0x901       	342	1680	0xf779	540	0xf779	0xfa21804
...

The function of Nexus wasn't affected but for getting rid of continuous logging of memory leak message from logfile, reboot this SUP.
Memory leak message had gone because the queues was decreased. But new sup/342/pers entries are still logging continuously.
`show system internal mts buffers summary`
node    sapno    recv_q    pers_q    npers_q    log_q
sup    5657    3    0    0    0
sup    284    0    4    0    0
sup    342    0    1122    0    0
`show system internal mts buffers details`
sup/342/pers    2805408            0x901           342    0x901           342    1680    0x2b62b    540    0x2b62b    0xfa90804
sup/342/pers    2805406            0x901           342    0x901           342    1680    0x2b632    540    0x2b632    0xfa91004
sup/342/pers    2802397            0x901           342    0x901           342    1680    0x2b6e1    540    0x2b6e1    0xfa90c04
sup/342/pers    2802396            0x901           342    0x901           342    1680    0x2b6e8    540    0x2b6e8    0xfa91804
sup/342/pers    2780653            0x901           342    0x901           342    1680    0x2dd5d    540    0x2dd5d    0xfa96804
sup/342/pers    2777638            0x901           342    0x901           342    1680    0x2e66c    540    0x2e66c    0xfa91c04
sup/342/pers    2777638            0x901           342    0x901           342    1680    0x2e673    540    0x2e673    0xfa96c04
....

The customer is using EEM.

Conditions:
Please refer Eng-Notes
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