From: Luis Chamberlain <mcgrof@kernel•org>
To: Matthias Maennich <maennich@google•com>
Cc: Heiner Kallweit <hkallweit1@gmail•com>,
Jessica Yu <jeyu@kernel•org>,
linux-kernel@vger•kernel.org, netdev@vger•kernel.org,
Andrew Lunn <andrew@lunn•ch>,
Florian Fainelli <f.fainelli@gmail•com>
Subject: Re: Module loading problem since 5.3
Date: Wed, 16 Oct 2019 12:50:30 +0000 [thread overview]
Message-ID: <20191016125030.GH16384@42.do-not-panic.com> (raw)
In-Reply-To: <20191014144440.GG35313@google.com>
On Mon, Oct 14, 2019 at 03:44:40PM +0100, Matthias Maennich wrote:
> Hi Luis!
>
> On Mon, Oct 14, 2019 at 08:52:35AM +0000, Luis Chamberlain wrote:
> > On Fri, Oct 11, 2019 at 09:26:05PM +0200, Heiner Kallweit wrote:
> > > 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
> >
> > Can you have your user with issues either revert 8651ec01daed or apply the fixes
> > mentioned by Matthias to see if that was the issue?
> >
> > Matthias what module did you run into which let you run into the issue
> > with depmod? I ask as I think it would be wise for us to add a test case
> > using lib/test_kmod.c and tools/testing/selftests/kmod/kmod.sh for the
> > regression you detected.
>
> The depmod warning can be reproduced when using a symbol that is built
> into vmlinux and used from a module. E.g. with CONFIG_USB_STORAGE=y and
> CONFIG_USB_UAS=m, the symbol `usb_stor_adjust_quirks` is built in with
> namespace USB_STORAGE and depmod stumbles upon this emitting the
> following warning (e.g. during make modules_install).
>
> depmod: WARNING: [...]/uas.ko needs unknown symbol usb_stor_adjust_quirks
>
> As there is another (less intrusive) way of implementing the namespace
> feature, I posted a patch series [1] on last Thursday that should
> mitigate the issue as the ksymtab entries depmod eventually relies on
> are no longer carrying the namespace in their names.
>
> Cheers,
> Matthias
>
> [1] https://lore.kernel.org/lkml/20191010151443.7399-1-maennich@google.com/
Yes but kmalloc() is built-in, and used by *all* drivers compiled as
modules, so why was that an issue?
Luis
next prev parent reply other threads:[~2019-10-16 12:50 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-10 16:50 Module loading problem since 5.3 Heiner Kallweit
[not found] ` <CAB=NE6XdVXMnq7pgmXxv4Qicu7=xrtQC-b2sXAfVxiAq68NMKg@mail.gmail.com>
2019-10-11 19:26 ` Heiner Kallweit
2019-10-14 8:52 ` Luis Chamberlain
2019-10-14 14:44 ` Matthias Maennich
2019-10-16 12:50 ` Luis Chamberlain [this message]
2019-10-16 13:37 ` Matthias Maennich
2019-10-18 12:18 ` Luis Chamberlain
2019-10-23 10:49 ` Matthias Maennich
2019-10-23 12:35 ` Luis Chamberlain
2019-10-24 9:22 ` Matthias Maennich
2019-10-14 10:01 ` Jessica Yu
2019-10-14 10:32 ` Luis Chamberlain
2019-10-14 18:16 ` Heiner Kallweit
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