From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Luis Chamberlain <mcgrof@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>,
ast@kernel.org, axboe@kernel.dk, bfields@fieldses.org,
bridge@lists.linux-foundation.org, chainsaw@gentoo.org,
christian.brauner@ubuntu.com, chuck.lever@oracle.com,
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linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org,
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ravenexp@gmail.com, roopa@cumulusnetworks.com, serge@hallyn.com,
slyfox@gentoo.org, viro@zeniv.linux.org.uk,
yangtiezhu@loongson.cn, netdev@vger.kernel.org,
markward@linux.ibm.com, linux-s390 <linux-s390@vger.kernel.org>
Subject: Re: linux-next: umh: fix processed error when UMH_WAIT_PROC is used seems to break linux bridge on s390x (bisected)
Date: Wed, 24 Jun 2020 20:32:12 +0200 [thread overview]
Message-ID: <4d8fbcea-a892-3453-091f-d57c03f9aa90@de.ibm.com> (raw)
In-Reply-To: <4e27098e-ac8d-98f0-3a9a-ea25242e24ec@de.ibm.com>
On 24.06.20 20:09, Christian Borntraeger wrote:
>
>
> On 24.06.20 19:58, Christian Borntraeger wrote:
>>
>>
>> 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....
>
> Just reverting the umh.c parts like this makes the problem go away.
>
> diff --git a/kernel/umh.c b/kernel/umh.c
> index f81e8698e36e..79f139a7ca03 100644
> --- a/kernel/umh.c
> +++ b/kernel/umh.c
> @@ -154,8 +154,8 @@ static void call_usermodehelper_exec_sync(struct subprocess_info *sub_info)
> * the real error code is already in sub_info->retval or
> * sub_info->retval is 0 anyway, so don't mess with it then.
> */
> - if (KWIFEXITED(ret))
> - sub_info->retval = KWEXITSTATUS(ret);
> + if (ret)
> + sub_info->retval = ret;
> }
>
> /* Restore default kernel sig handler */
I instrumented this:
[ 5.118528] ret=0x100 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x1
[ 9.409235] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 10.114914] ret=0x100 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x1
[ 10.116308] ret=0x100 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x1
[ 10.117690] ret=0x100 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x1
[ 10.118732] ret=0x100 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x1
[ 10.119899] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 10.121365] ret=0x100 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x1
[ 10.128044] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 10.945814] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 10.962799] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 10.983755] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 10.992705] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 11.118877] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 11.124359] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 11.129364] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 11.142139] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 11.148385] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 11.153686] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 11.158861] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 11.164068] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 11.192445] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 11.200605] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 11.208493] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 11.216612] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 11.226467] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 11.525363] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 11.532758] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 11.535279] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 11.697660] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 11.701634] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 11.818652] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 11.836228] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 12.082266] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
[ 40.965898] ret=0x0 KWIFEXITED(ret) = 0x1 KWEXITSTATUS(ret)= 0x0
So the translations look correct. But your change is actually a sematic change
if(ret) will only trigger if there is an error
if (KWIFEXITED(ret)) will always trigger when the process ends. So we will always overwrite -ECHILD
and we did not do it before.
next prev parent reply other threads:[~2020-06-24 18:32 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-10 15:49 [PATCH 0/5] kmod/umh: a few fixes Luis R. Rodriguez
2020-06-10 15:49 ` [PATCH 1/5] selftests: kmod: Use variable NAME in kmod_test_0001() Luis R. Rodriguez
2020-06-10 15:49 ` [PATCH 2/5] kmod: Remove redundant "be an" in the comment Luis R. Rodriguez
2020-06-10 15:49 ` [PATCH 3/5] test_kmod: Avoid potential double free in trigger_config_run_type() Luis R. Rodriguez
2020-06-10 15:49 ` [PATCH 4/5] umh: fix processed error when UMH_WAIT_PROC is used Luis R. Rodriguez
2020-06-23 14:11 ` linux-next: umh: fix processed error when UMH_WAIT_PROC is used seems to break linux bridge on s390x (bisected) Christian Borntraeger
2020-06-23 14:23 ` Christian Borntraeger
2020-06-24 11:11 ` Christian Borntraeger
2020-06-24 12:05 ` Luis Chamberlain
2020-06-24 13:17 ` Luis Chamberlain
2020-06-24 16:13 ` Luis Chamberlain
2020-06-24 14:43 ` Christoph Hellwig
2020-06-24 15:54 ` Christian Borntraeger
2020-06-24 16:09 ` Luis Chamberlain
2020-06-24 17:58 ` Christian Borntraeger
2020-06-24 18:09 ` Christian Borntraeger
2020-06-24 18:32 ` Christian Borntraeger [this message]
2020-06-24 18:37 ` Christian Borntraeger
2020-06-25 13:26 ` Christian Borntraeger
2020-06-26 2:54 ` Luis Chamberlain
2020-06-26 5:22 ` Christian Borntraeger
2020-06-26 9:00 ` Christoph Hellwig
2020-06-26 11:40 ` Luis Chamberlain
2020-06-26 11:50 ` Luis Chamberlain
2020-06-30 17:57 ` Luis Chamberlain
2020-07-01 10:08 ` Christian Borntraeger
2020-07-01 13:24 ` Tetsuo Handa
2020-07-01 13:53 ` Luis Chamberlain
2020-07-01 14:08 ` Tetsuo Handa
2020-07-01 15:38 ` Luis Chamberlain
2020-07-01 15:48 ` Christian Borntraeger
2020-07-01 15:58 ` Luis Chamberlain
2020-07-01 16:01 ` Christian Borntraeger
2020-07-02 4:26 ` Tetsuo Handa
2020-07-02 19:46 ` Luis Chamberlain
2020-07-03 0:52 ` Tetsuo Handa
2020-07-03 13:28 ` Luis Chamberlain
2020-07-01 15:26 ` Christian Borntraeger
2020-07-01 13:46 ` Luis Chamberlain
2020-06-10 15:49 ` [PATCH 5/5] selftests: simplify kmod failure value Luis R. Rodriguez
2020-06-18 0:43 ` [PATCH 0/5] kmod/umh: a few fixes Andrew Morton
2020-06-19 20:46 ` Luis Chamberlain
2020-06-19 21:07 ` Luis Chamberlain
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