netdev - Re: upgrade to 3.8.1 : BUG Scheduling while atomic in bonding driver:

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Message-ID: <513862DA.20704@linux.vnet.ibm.com>
Date:	Thu, 07 Mar 2013 17:50:18 +0800
From:	Michael Wang <wangyun@...ux.vnet.ibm.com>
To:	Linda Walsh <lkml@...nx.org>
CC:	Eric Dumazet <eric.dumazet@...il.com>,
	Linux-Kernel <linux-kernel@...r.kernel.org>,
	netdev <netdev@...r.kernel.org>, Jay Vosburgh <fubar@...ibm.com>,
	Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
	Cong Wang <xiyou.wangcong@...il.com>
Subject: Re: upgrade to 3.8.1 : BUG Scheduling while atomic in bonding driver:

On 03/07/2013 04:50 PM, Linda Walsh wrote:
> 
> I am *not* seeing the bug in 3.8.2 with the 2nd patch applied (in
> addition to the first)...

So that means bond lock is the reason, nice, but this is really not a
good fix if we just unlock it...

The better way is to move the cycle wait logical out of the
bond_update_speed_duplex() IMO, I think we need the folk who work on
this driver to make the decision ;-)

Regards,
Michael Wang

> 
> 
> Michael Wang wrote:
>>
>>
>> And both bond_enslave() and bond_mii_monitor() are using bond_update_speed_duplex()
>> with preempt disabled.
>>
>> Along with the changes in bond_enslave(), I think you also need this (untested):
>>
>> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>> index 11d01d6..9af143a 100644
>> --- a/drivers/net/bonding/bond_main.c
>> +++ b/drivers/net/bonding/bond_main.c
>> @@ -2373,7 +2373,9 @@ static void bond_miimon_commit(struct bonding *bond)
>>                                 bond_set_backup_slave(slave);
>>                         }
>>
>> +                       read_unlock(&bond->lock);
>>                         bond_update_speed_duplex(slave);
>> +                       read_lock(&bond->lock);
>>
>>                         pr_info("%s: link status definitely up for interface %s, %u Mbps %s duplex.\n",
>>                                 bond->dev->name, slave->dev->name,
>>
>>
>> Regards,
>> Michael Wang
>>
>>   
>>
> 

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