Re: [PATCH AUTOSEL 5.9 27/39] sched/idle: Fix arch_cpu_idle() vs tracing

[Sasha Levin]

On Thu, Dec 03, 2020 at 06:10:15PM +0100, Peter Zijlstra wrote:
> On Thu, Dec 03, 2020 at 03:54:42PM +0100, Heiko Carstens wrote:
> > On Thu, Dec 03, 2020 at 08:28:21AM -0500, Sasha Levin wrote:
> > > From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> > >
> > > [ Upstream commit 58c644ba512cfbc2e39b758dd979edd1d6d00e27 ]
> > >
> > > We call arch_cpu_idle() with RCU disabled, but then use
> > > local_irq_{en,dis}able(), which invokes tracing, which relies on RCU.
> > >
> > > Switch all arch_cpu_idle() implementations to use
> > > raw_local_irq_{en,dis}able() and carefully manage the
> > > lockdep,rcu,tracing state like we do in entry.
> > >
> > > (XXX: we really should change arch_cpu_idle() to not return with
> > > interrupts enabled)
> > >
> > > Reported-by: Sven Schnelle <svens@xxxxxxxxxxxxx>
> > > Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> > > Reviewed-by: Mark Rutland <mark.rutland@xxxxxxx>
> > > Tested-by: Mark Rutland <mark.rutland@xxxxxxx>
> > > Link: https://lkml.kernel.org/r/20201120114925.594122626@xxxxxxxxxxxxx
> > > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> >
> > This patch broke s390 irq state tracing. A patch to fix this is
> > scheduled to be merged upstream today (hopefully).
> > Therefore I think this patch should not yet go into 5.9 stable.
>
> Agreed.

I'll also grab b1cae1f84a0f ("s390: fix irq state tracing"). Thanks!

--
Thanks,
Sasha