Bug 833110 - Kernel Crash after unloading the bonding moudle
Kernel Crash after unloading the bonding moudle
Status: CLOSED DUPLICATE of bug 823822
Product: Red Hat Enterprise Linux 6
Classification: Red Hat
Component: kernel (Show other bugs)
All Linux
unspecified Severity urgent
: rc
: ---
Assigned To: Veaceslav Falico
Red Hat Kernel QE team
Depends On:
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Reported: 2012-06-18 11:15 EDT by Talat
Modified: 2014-09-30 19:44 EDT (History)
7 users (show)

See Also:
Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
Last Closed: 2012-06-24 13:04:46 EDT
Type: Bug
Regression: ---
Mount Type: ---
Documentation: ---
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Category: ---
oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
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2012-06-18 11:15 EDT, Talat
no flags Details

  None (edit)
Description Talat 2012-06-18 11:15:47 EDT
Created attachment 592688 [details]

Description of problem:
The machine get Kernel Crash after creating an bond of two interfaces, creating vlan on the bond and unload the bonding moudle.
Version-Release number of selected component (if applicable):2.6.32-274.el6.x86_64 

How reproducible:
This failure is 100% reproducible.

Steps to Reproduce:
1. Create an balance- alb bond.
2. Create a tagged vlan interface on said bond
3. unload the bonding moudle "modprobe -r bonding"
Actual results:
Kernel Panic

Expected results:
1. Delete all the vlans that on the bond.
2. Delete the bond.
3. detach the slave interfaces  

Additional info:
Comment 2 Michael Chapman 2012-06-22 20:46:38 EDT
I have encountered this bug as well. The panic is "kernel BUG at net/8021q/vlan.c:796".

Reverting the kernel patches:

- [net] bonding: assign slaves their own vlan_groups (Neil Horman) [804232]
- [net] vlan: Add helper functions to manage vlans on bonds and slaves (Neil Horman) [804232]

appears to fix the problem.
Comment 3 Neil Horman 2012-06-24 13:04:46 EDT
This should be fixed in kernel-2.6.32-280.el6 forward

*** This bug has been marked as a duplicate of bug 823822 ***
Comment 4 Michael Chapman 2012-06-26 22:39:49 EDT
I just tested the patch for this that was posted in bug 834764 comment 16 (patch URL: https://bugzilla.redhat.com/attachment.cgi?id=594190). It doesn't appear to fix the problem: I still hit a kernel bug at net/8021q/vlan.c:796.

Looking at what the patch does to bond_del_vlans_from_slave, it looks like sgrp->nr_vlans is not decremented if the slave doesn't support NETIF_F_HW_VLAN_FILTER, even though it may have been incremented in bond_vlan_rx_add_vid. I think this means it's still possible for the vlan group to leak, leading to the crash when the 8021q module is unloaded.
Comment 5 Neil Horman 2012-06-27 06:58:39 EDT
yup, looks like you're right, please open a new bz to track that and I'll square it away.  Thanks!

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