linux-kernel - Re: [PATCH v2 10/11] lockdep: Only trace IRQ edges

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Message-ID: <20200908142215.GU1362448@hirez.programming.kicks-ass.net>
Date:   Tue, 8 Sep 2020 16:22:15 +0200
From:   peterz@...radead.org
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     linux-kernel@...r.kernel.org, mingo@...nel.org, will@...nel.org,
        npiggin@...il.com, elver@...gle.com, jgross@...e.com,
        paulmck@...nel.org, rostedt@...dmis.org, rjw@...ysocki.net,
        joel@...lfernandes.org, svens@...ux.ibm.com, tglx@...utronix.de,
        davem@...emloft.net
Subject: Re: [PATCH v2 10/11] lockdep: Only trace IRQ edges

On Wed, Sep 02, 2020 at 06:48:30AM -0700, Guenter Roeck wrote:
> On 9/2/20 2:12 AM, peterz@...radead.org wrote:
> > On Wed, Sep 02, 2020 at 11:09:35AM +0200, peterz@...radead.org wrote:
> >> On Tue, Sep 01, 2020 at 09:21:37PM -0700, Guenter Roeck wrote:
> >>> [    0.000000] WARNING: CPU: 0 PID: 0 at kernel/locking/lockdep.c:4875 check_flags.part.39+0x280/0x2a0
> >>> [    0.000000] DEBUG_LOCKS_WARN_ON(lockdep_hardirqs_enabled())
> >>
> >>> [    0.000000] [<00000000004cff18>] lock_acquire+0x218/0x4e0
> >>> [    0.000000] [<0000000000d740c8>] _raw_spin_lock+0x28/0x40
> >>> [    0.000000] [<00000000009870f4>] p1275_cmd_direct+0x14/0x60
> >>
> >> Lol! yes, I can see that going side-ways... let me poke at that.
> > 
> > I suspect this will do.
> > 
> > diff --git a/arch/sparc/prom/p1275.c b/arch/sparc/prom/p1275.c
> > index 889aa602f8d8..7cfe88e30b52 100644
> > --- a/arch/sparc/prom/p1275.c
> > +++ b/arch/sparc/prom/p1275.c
> > @@ -38,7 +38,7 @@ void p1275_cmd_direct(unsigned long *args)
> >  	unsigned long flags;
> > 
> >  	local_save_flags(flags);
> > -	local_irq_restore((unsigned long)PIL_NMI);
> > +	arch_local_irq_restore((unsigned long)PIL_NMI);
> >  	raw_spin_lock(&prom_entry_lock);
> > 
> >  	prom_world(1);
> > 
> No, that doesn't help. Even removing that line entirely doesn't help.
> The problem seems to be that interrupts are not enabled in the first
> place. But why wasn't this a problem before ?

Previously every interrupt opt would disable/enable things, now we only
update state when something actually changes.

Anyway, I'm struggling with qemu-system-sparc64, I've got a sparc64
cross booting to mount, but I'm not seeing this, could you get me your
specific qemu cmdline please?