netdev - Re: linux-next: umh: fix processed error when UMH_WAIT_PROC is used seems to break linux bridge on s390x (bisected)

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Message-ID: <ea41e2a9-61f7-aec1-79e5-7b08b6dd5119@de.ibm.com>
Date:   Wed, 24 Jun 2020 19:58:37 +0200
From:   Christian Borntraeger <borntraeger@...ibm.com>
To:     Luis Chamberlain <mcgrof@...nel.org>
Cc:     Christoph Hellwig <hch@...radead.org>, ast@...nel.org,
        axboe@...nel.dk, bfields@...ldses.org,
        bridge@...ts.linux-foundation.org, chainsaw@...too.org,
        christian.brauner@...ntu.com, chuck.lever@...cle.com,
        davem@...emloft.net, dhowells@...hat.com,
        gregkh@...uxfoundation.org, jarkko.sakkinen@...ux.intel.com,
        jmorris@...ei.org, josh@...htriplett.org, keescook@...omium.org,
        keyrings@...r.kernel.org, kuba@...nel.org,
        lars.ellenberg@...bit.com, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-nfs@...r.kernel.org,
        linux-security-module@...r.kernel.org, nikolay@...ulusnetworks.com,
        philipp.reisner@...bit.com, ravenexp@...il.com,
        roopa@...ulusnetworks.com, serge@...lyn.com, slyfox@...too.org,
        viro@...iv.linux.org.uk, yangtiezhu@...ngson.cn,
        netdev@...r.kernel.org, markward@...ux.ibm.com,
        linux-s390 <linux-s390@...r.kernel.org>
Subject: Re: linux-next: umh: fix processed error when UMH_WAIT_PROC is used
 seems to break linux bridge on s390x (bisected)



On 24.06.20 18:09, Luis Chamberlain wrote:
> On Wed, Jun 24, 2020 at 05:54:46PM +0200, Christian Borntraeger wrote:
>>
>>
>> On 24.06.20 16:43, Christoph Hellwig wrote:
>>> On Wed, Jun 24, 2020 at 01:11:54PM +0200, Christian Borntraeger wrote:
>>>> Does anyone have an idea why "umh: fix processed error when UMH_WAIT_PROC is used" breaks the
>>>> linux-bridge on s390?
>>>
>>> Are we even sure this is s390 specific and doesn't happen on other
>>> architectures with the same bridge setup?
>>
>> Fair point. AFAIK nobody has tested this yet on x86.
> 
> Regardless, can you enable dynamic debug prints, to see if the kernel
> reveals anything on the bridge code which may be relevant:
> 
> echo "file net/bridge/* +p" > /sys/kernel/debug/dynamic_debug/control
> 
>   Luis

When I start a guest the following happens with the patch:

[   47.420237] virbr0: port 2(vnet0) entered blocking state
[   47.420242] virbr0: port 2(vnet0) entered disabled state
[   47.420315] device vnet0 entered promiscuous mode
[   47.420365] virbr0: port 2(vnet0) event 16
[   47.420366] virbr0: br_fill_info event 16 port vnet0 master virbr0
[   47.420373] virbr0: toggle option: 12 state: 0 -> 0
[   47.420536] virbr0: port 2(vnet0) entered blocking state
[   47.420538] virbr0: port 2(vnet0) event 16
[   47.420539] virbr0: br_fill_info event 16 port vnet0 master virbr0

and the nothing happens.


without the patch
[   33.805410] virbr0: hello timer expired
[   35.805413] virbr0: hello timer expired
[   36.184349] virbr0: port 2(vnet0) entered blocking state
[   36.184353] virbr0: port 2(vnet0) entered disabled state
[   36.184427] device vnet0 entered promiscuous mode
[   36.184479] virbr0: port 2(vnet0) event 16
[   36.184480] virbr0: br_fill_info event 16 port vnet0 master virbr0
[   36.184487] virbr0: toggle option: 12 state: 0 -> 0
[   36.184636] virbr0: port 2(vnet0) entered blocking state
[   36.184638] virbr0: port 2(vnet0) entered listening state
[   36.184639] virbr0: port 2(vnet0) event 16
[   36.184640] virbr0: br_fill_info event 16 port vnet0 master virbr0
[   36.184645] virbr0: port 2(vnet0) event 16
[   36.184646] virbr0: br_fill_info event 16 port vnet0 master virbr0
[   37.805478] virbr0: hello timer expired
[   38.205413] virbr0: port 2(vnet0) forward delay timer
[   38.205414] virbr0: port 2(vnet0) entered learning state
[   38.205427] virbr0: port 2(vnet0) event 16
[   38.205430] virbr0: br_fill_info event 16 port vnet0 master virbr0
[   38.765414] virbr0: port 2(vnet0) hold timer expired
[   39.805415] virbr0: hello timer expired
[   40.285410] virbr0: port 2(vnet0) forward delay timer
[   40.285411] virbr0: port 2(vnet0) entered forwarding state
[   40.285418] virbr0: topology change detected, propagating
[   40.285420] virbr0: decreasing ageing time to 400
[   40.285427] virbr0: port 2(vnet0) event 16
[   40.285432] virbr0: br_fill_info event 16 port vnet0 master virbr0
[   40.765408] virbr0: port 2(vnet0) hold timer expired
[   41.805415] virbr0: hello timer expired
[   42.765426] virbr0: port 2(vnet0) hold timer expired
[   43.805425] virbr0: hello timer expired
[   44.765426] virbr0: port 2(vnet0) hold timer expired
[   45.805418] virbr0: hello timer expired

and continuing....