linux-kernel - Re: WARNING: CPU: 1 PID: 1 at net/core/netpoll.c:370 netpoll_send_skb+0x1fc/0x20c at boot when netconsole is enabled (kernel v6.9-rc5, v6.8.7, sungem, PowerMac G4 DP)

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Message-ID: <20240506072645.448bc49f@kernel.org>
Date: Mon, 6 May 2024 07:26:45 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Erhard Furtner <erhard_f@...lbox.org>
Cc: netdev@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
 linux-kernel@...r.kernel.org
Subject: Re: WARNING: CPU: 1 PID: 1 at net/core/netpoll.c:370
 netpoll_send_skb+0x1fc/0x20c at boot when netconsole is enabled (kernel
 v6.9-rc5, v6.8.7, sungem, PowerMac G4 DP)

On Sun, 5 May 2024 23:27:13 +0200 Erhard Furtner wrote:
> > On Sun, 28 Apr 2024 12:53:06 +0200 Erhard Furtner wrote:  
> > > With netconsole enabled I get this "WARNING: CPU: 1 PID: 1 at
> > > net/core/netpoll.c:370 netpoll_send_skb+0x1fc/0x20c" and "WARNING:
> > > CPU: 1 PID: 1 at kernel/locking/irqflag-debug.c:10
> > > warn_bogus_irq_restore+0x30/0x44" at boot on my PowerMac G4 DP.
> > > Happens more often than not (6-7 out of 10 times booting):    
> > 
> > Could you try with LOCKDEP enabled?
> > I wonder if irqs_disabled() behaves differently than we expect.  
> 
> Ok, after a few tries I got a "BUG: spinlock wrong CPU on CPU#0, swapper/0/1" LOCKDEP hit. But this does not happen every time when I get the netpoll_send WARNING:

Oh, can you try deleting the gem_poll_controller() function?
Unhook it from ndo_poll_controller and remove it completely.