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Subject: Re: Module loading problem since 5.3
To:     Jessica Yu <jeyu@kernel.org>
Cc:     Luis Chamberlain <mcgrof@kernel.org>, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org, Andrew Lunn <andrew@lunn.ch>,
        Florian Fainelli <f.fainelli@gmail.com>
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 <875eecfb-618a-4989-3b9f-f8272b8d3746@gmail.com>
 <20191014100143.GA6525@linux-8ccs>
From:   Heiner Kallweit <hkallweit1@gmail.com>
Message-ID: <dbeb6e00-bc8f-e3ed-5a1c-57eace6dee17@gmail.com>
Date:   Mon, 14 Oct 2019 20:16:48 +0200
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On 14.10.2019 12:01, Jessica Yu wrote:
> +++ Heiner Kallweit [11/10/19 21:26 +0200]:
>> On 10.10.2019 19:15, Luis Chamberlain wrote:
>>>
>>>
>>> On Thu, Oct 10, 2019, 6:50 PM Heiner Kallweit <hkallweit1@gmail.com <mailto:hkallweit1@gmail.com>> wrote:
>>>
>>>        MODULE_SOFTDEP("pre: realtek")
>>>
>>>     Are you aware of any current issues with module loading
>>>     that could cause this problem?
>>>
>>>
>>> Nope. But then again I was not aware of MODULE_SOFTDEP(). I'd encourage an extension to lib/kmod.c or something similar which stress tests this. One way that comes to mind to test this is to allow a new tests case which loads two drives which co depend on each other using this macro. That'll surely blow things up fast. That is, the current kmod tests uses request_module() or get_fs_type(), you'd want a new test case with this added using then two new dummy test drivers with the macro dependency.
>>>
>>> If you want to resolve this using a more tested path, you could have request_module() be used as that is currently tested. Perhaps a test patch for that can rule out if it's the macro magic which is the issue.
>>>
>>>   Luis
>>>
>> Maybe issue is related to a bug in introduction of symbol namespaces, see here:
>> https://lkml.org/lkml/2019/10/11/659
> 
> If you're running into depmod and module loading issues with kernels >=5.3-rc1,
> it's likely due to the namespaces patchset and we're working on
> getting all the kinks fixed. Could you please ask the bug reporter to
> try the latest -rc kernel with these set of fixes applied on top?
> 
>   https://lore.kernel.org/linux-modules/20191010151443.7399-1-maennich@google.com/
> 
> They fix a known depmod issue caused by our __ksymtab naming scheme,
> which is being reverted in favor of extracting the namespace from
> __kstrtabns and __ksymtab_strings. These fixes will be in by -rc4.
> 
Thanks a lot, I'll check with the affected users.
Maybe worth to be noted: I wasn't able to reproduce the module loading issue
on my systems, one difference is that affected users have kmod utils
version 25 and I have version 26. I asked them to upgrade to v26 and re-test,
feedback is pending.

> Thanks,
> 
> Jessica
> 
> 
> .
> 
Heiner