netdev - Re: [BUG] Deadlock in _cfg80211_unregister

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Date:   Fri, 14 May 2021 10:26:25 +0200
From:   Johannes Berg <johannes@...solutions.net>
To:     Maximilian Luz <luzmaximilian@...il.com>,
        linux-wireless@...r.kernel.org
Cc:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        Amitkumar Karwar <amitkarwar@...il.com>,
        Ganapathi Bhat <ganapathi.bhat@....com>,
        Xinming Hu <huxinming820@...il.com>
Subject: Re: [BUG] Deadlock in _cfg80211_unregister_wdev()

On Fri, 2021-05-14 at 01:07 +0200, Maximilian Luz wrote:
> Following commit a05829a7222e ("cfg80211: avoid holding the RTNL when
> calling the driver"), the mwifiex_pcie module fails to unload. This also
> prevents the device from rebooting / shutting down.
> 
> Attempting to unload the module
> 

I'm *guessing* that you're attempting to unload the module while the
interface is still up, i.e. you didn't "ip link set wlan0 down" first?

If so, that is likely fixed by this commit as well:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ea6b2098dd02789f68770fd3d5a373732207be2f

However, your log says:

> [  245.504764]       Tainted: G         C OE     5.11.0-1-surface-dev #2

so I have no idea what kernel you're using, because 5.11 did *not*
contain commit a05829a7222e ("cfg80211: avoid holding the RTNL when
calling the driver"). If you backported the bug you get to be
responsible for backporting the fixes too?

If that's all not solving the issue then please try to resolve with gdb
what line of code "cfg80211_netdev_notifier_call+0x12a" is, and please
also clarify exactly what (upstream!) kernel you're using.

johannes