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Bug 1815875

Summary: NetworkManager fails to delete qdisc (also resulting in scalability issues)
Product: Red Hat Enterprise Linux 8 Reporter: Thomas Haller <thaller>
Component: NetworkManagerAssignee: Beniamino Galvani <bgalvani>
Status: CLOSED ERRATA QA Contact: Desktop QE <desktop-qa-list>
Severity: medium Docs Contact:
Priority: medium    
Version: 8.3CC: acardace, atragler, bgalvani, jmaxwell, lrintel, mleitner, mmethot, rkhan, sukulkar, thaller, till, vbenes
Target Milestone: rcFlags: pm-rhel: mirror+
Target Release: 8.0   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: NetworkManager-1.25.2-1.el8 Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2020-11-04 01:49:27 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 1807630    

Description Thomas Haller 2020-03-22 10:52:12 UTC
seems NM may send requests to delete qdisc, which kernel replies with 

> Mar 22 10:32:02.293988 dev-h-vrt-013 NetworkManager[11102]: <debug> [1584865922.2939] platform: (ens1f0) qdisc: delete fq_codel dev 865 family 0 handle 0 parent 1 info 1 limit 10240 flows 1024 target 4999 interval 99999 quantum 1514 memory_limit 33554432 ecn
> Mar 22 10:32:02.294009 dev-h-vrt-013 NetworkManager[11102]: <debug> [1584865922.2940] platform-linux: netlink: recvmsg: error message from kernel: No such file or directory (2) "Failed to find qdisc with specified classid" for request 604864
> Mar 22 10:32:02.294018 dev-h-vrt-013 NetworkManager[11102]: <debug> [1584865922.2940] platform-linux: do-delete-qdisc[865: 1]: failure 2 (No such file or directory - Failed to find qdisc with specified classid), meaning the object was already removed

NM then thinks that the element is already gone and that its cache is out of date. It will thus request a full dump of the QDiscs to fix the (assumed) cache consistency.

that means, if you try to delete N qdiscs, not only will it fail, it will also result in N full dumps of all qdiscs. That is a scalability issue as well.


See log here: https://bugzilla.redhat.com/show_bug.cgi?id=1815060#c12

Comment 10 errata-xmlrpc 2020-11-04 01:49:27 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (NetworkManager bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2020:4499